Journal of
Nannoplankton Research
INA 19 abstracts, Conwy, UK
INA 19 | special volume | september 2024

19th INA Conference, CONWY, UK, 2024, abstracts © 2024 International Nannoplankton Association
Printed by The Sheridan Press, Hannover PA, USA1		Convenors
SIMON COLE				TAMSIN LAWRENCE

		

Local Organising Committee
SIMON COLE				TAMSIN LAWRENCE

		
		
		

		

(PetroStrat – UK)(PetroStrat – UK)

ANDREA PARDON			(Viridien – UK) 			

EMMA SHELDON(GEUS – Denmark)

Scientific Committee
SIMON COLE				TAMSIN LAWRENCE(PetroStrat – UK)

PAUL BOWN

TOM DUNKLEY JONES(University College London – UK)

ALBA GONZALEZ-LANCHAS(University of Oxford – UK)(Network Stratigraphic – UK)

MATT HAMPTONEMANUELA MATTIOLI(Network Stratigraphic – UK)

EMMA SHELDON(Université Lyon – France)

MARIEM SAAVEDRA(GEUS – Denmark)(University of Portsmouth – UK)

Conference Local Support
JENNIE BULLJANET DAVISJENS THISSENMICHAEL AMOOMARINA CIUMMELLIAGNIESZKA PALCZYNSKAJANINE PENDLETON – Webmaster

LIAM GALLAGHER(University of Birmingham – UK)

JEREMY YOUNG(University College London – UK)

TEENA CHAUHANCHRISTIAN JOACHIM
SARAH-MAY VINNELL
CHRISTOPHER CURTIS – IT

(PetroStrat – UK)

MATT HAMPTON – Treasurer(Network Stratigraphic – UK)

INA19 Abstract Volume Guest Editor
LAUREL BYBELL
Field Trip Contributors
ROB CROSSLEYJONATHAN WILKINS(GeoMôn / Viridien – UK)				(X-ray Mineral Services (retired) – UK)

PETER LUCAS
HANNAH TORRANCEDYLAN ROBERTS
GARETH SMITH
JACK WALKER(PetroStrat – UK)

ON THE COVER: INA19 logo created by Bridie Cheeseman (https://www.bridiecheeseman.com; Instagram @bridiecheeseman)

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A very special thank you to all the sponsors of INA 19 Conwy!

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Croeso / Welcome to INA19 Conwy!
7th to 15th September 2024
Saturday 7th - Pre-conference field trip, Ynys Môn (Anglesey)
Sunday 8th - Ice breaker party hosted by PetroStrat at Conwy Castle
Monday 9th to Thursday 12th – Conference sessions, St George’s Hotel, Llandudno
Friday 13th to Sunday 15th – Post-conference field trip, Eryri National Park (Snowdonia)

Left: Llandudno Promenade; right top, Conwy Castle; right bottom, Great Orme, Llandudno. Photo credit: Tamsin Lawrence (PetroStrat)

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Croeso and Welcome to INA 19 Conwy!
We are delighted to be hosting the 19th International Nannoplankton Association meeting in North Wales,
UK! This year’s meeting will be taking place in the seaside town of Llandudno, and based in the St George’s
Hotel located on our stunning Victorian seafront. We look forward to welcoming over 100 participants from27 countries!
The meeting will host talks over four days, focusing on biostratigraphy, methods and taxonomy, OAEs,
hyperthermals, palaeoecology, and evolutionary history from the Jurassic to Recent. We will also be
hosting a number of workshops and masterclasses, as well as software and microscope demonstrations.
Finally, we look forward to welcoming sixth-form students from several local schools from Conwy County Borough, who will be introduced to the microscopic world of nannoplankton!
We have planned three field trips - to the mystical island of Anglesey (Ynys Môn), the Great Orme in
Llandudno (Y Gogarth), and a two night residential trip to Snowdonia – the Eryri National Park. Ourconference dinner will take place at Dylan’s, a seafront restaurant in Llandudno which champions local,
seasonal produce.
We look forward to showcasing the research of the nannoplankton community and welcome you all tobeautiful North Wales! We very much hope you will enjoy the meeting and your time in Wales!
Diolch yn fawr!
Simon Cole & Tamsin Lawrence
INA19 Convenors
PetroStrat (UK)

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INA19 Programme
Saturday 7 September 2024th

08:30 – 18:00
Pre-conference field trip - Ynys Môn (Anglesey)
Stops include Menai Bridge Viewpoint; The Mar-

10:15 – 10:30
Talk 3: Lassus et al. – A YOLO model for coccolithophore identification using images from ocean
water samples

quess of Anglesey's Column; Parys Mountain;
Newborough/Llanddwyn

Island;Llanfairpwll-

Coffee Break 10:30 – 11:00

gwyngyllgogerychwyrndrobwllllantysiliogogogoch
Session Two – “Life thru a lens” – Viewing(Rob Crossley, GeoMôn/Viridien).

the bigger picture through a microscope

Sunday 8th September 2024

(continued)

13:00 – 15:00
Masterclass:
ScientificWriting

11:00 – 11:15
Talk 4: Varol – Challenges of optical properties ofandReviewing(DeniseKulhanek, Kiel University; Jean Self-Trail, USGS;
Emma Sheldon, GEUS). Optional – sign up required.

calcareous nannofossils
11:15 – 11:30
Talk 5: Beaufort – Artificial intelligence used forautomatic detection of calcareous nannofossils with

13:00 – 16:00
Early Registration, St. George’s HotelSYRACO

17:00 – 19:30
Ice Breaker Party, Conwy Castle

searches using Scampi(Sponsored by PetroStrat)

Monday 9th September 2024
08:00 – 09:00
Late Registration – Conwy Suite, St Georges

11:30 – 11:45
Talk 6: Stefanowicz et al. – Nannofossil image
11:45 – 12:00
Talk 7: Hanson et al. (Tom Dunkley Jones
presenting) – Size-fraction coccolith stable isotopes
and Sr/Ca from the Miocene to Recent
Flash talks for poster session 12:00 – 12:30

HotelLunch break (lunch provided) 12:30 – 13:30
09:00 – 09:30
Opening announcements

Session Three – “Life thru a lens” – View-

Simon Cole & Tamsin Lawrence, INA19 Conveyors;

ing the bigger picture through a microscope

Emanuela Mattioli, INA President; Paul Cornick/(continued)

David Rutledge, PetroStrat Directors

Chairs: Matthew Hampton & Yi Zhang

Session One – “Life thru a lens” – Viewing

13:30 – 14:00
Keynote 2 (Talk 8): Lawrence & Sheldon – Nan-the bigger picture through a microscope

nofossil biostratigraphy in industry; female pio-

(continued)

neers in nannopaleontology and a story of life on

Chairs: Odysseus Archontikis & Emma Sheldon

the rigs

09:30 – 10:00
Keynote 1 (Talk 1): Mike Simmons – Biostratigra-

Session Three (continued) – Nannos in thephy and the energy transition

Age of the Dinosaurs – Jurassic

10:00 – 10:15
Talk 2: Young et al. – Developing tools to compile

14:00 – 14:15
Talk 9: Rutledge - Application of nannofossils (theand visualize nannofossil occurrence data

missing piece of the puzzle) from offshore New-INA19foundland: Upgrading the regional stratigraphy via
an integrated multidisciplinary approach7

17:00 – 17:15
Talk 19: Howe – Ultrastructure and taxonomy of

14:15 – 14:30
Talk 10: Chaumeil Rodríguez et al. – New bio-the Order Watznauriales

stratigraphic data for the Lower–Middle Jurassic Los

Day 1 Closing remarks 17:15 – 17:30

Molles Formation in the Picún Leufú area, Argentina

Tuesday 10th September 2024

14:30 – 14:45
Talk 11: Fraguas et al. – New insights on calcar-

Session One – “Who stole all the oxygen?”eous nannofossil biostratigraphy and paleoecology(Cretaceous Nannos and the OAEs)

around the Pliensbachian/Toarcian boundary in the

Chairs: Denise Kulhanek & Alessandro Menini

South Iberian paleomargin

09:00 – 09:15
Talk 20: Zhang et al. – Reconstructing Cretaceous

14:45 – 15:00
Talk 12: Jeremiah & Schwartz – Nannofossil

climate: Insights from a new calcareous nannofos-abundance and diversity changes – a reaction tosil occurrence databasechanging paleoenvironments in the late Tithonian

09:15 – 09:30
Talk 21: Self-Trail et al. – Calcareous nannofos-of the Flemish Pass Basin, offshore Newfoundland
15:00 – 15:15
Talk 13: Chowdhury et al. – The microscale exo-sils, Oceanic Anoxic Event 2, and the Cenomanian/skeletal reconstruction of the genus Nannoconus –USAtaxonomic insights

09:30 – 09:45
Talk 22: Schueth et al. – Unusual calcareous nan-

Coffee Break 15:15 – 15:45

nofossil assemblages from the Cenomanian–Turoni-

Turonian boundary in cores from eastern Louisiana,an (93.9 Ma) of North America: Implications for
Session Four – Nannos in the Age of the Dino-

nannofloral response to Oceanic Anoxic Event 2

saurs (continued) – Cretaceous

09:45 – 10:00
Talk 23: Tungo et al. – Morphometric analyses of

15:45 – 16:00
Talk 14: Aubry et al. – From alkenones to Creta-

Eprolithus floralis from Oceanic Anoxic Event 2 inceous marine Isochrysidales to coccoliths

the Eastbourne section

16:00 – 16:15
Talk 15: Anton & Melinte-Dobrinescu – Calcar-

10:00 – 10:15
Talk 24: Godet et al. – Using extraterrestrial 3He to

eous nannofossils of the Valanginian/Hauterivian

reconstruct terrigenous fluxes and their impacts onboundary interval in the Romanian Carpathians

marine primary productivity and carbon burial dur-

16:15 – 16:30
Talk 16: Bottini et al. – Aptian–Albian calcareous

ing OAE2 in the Vocontian Basin (SE France)

nannofossils from the South Atlantic Ocean: Impli-

10:15 – 10:30
Talk 25: Erba et al. – Calcareous nannofossil pa-

cations for paleoclimate and paleogeography

laeoceanography across Oceanic Anoxic Event 3:

16:30 – 16:45
Talk 17: Lamm et al. – Calcareous nannofossils

From local to global perturbations

from the Poggio le Guaine core (Umbria-Marche

Coffee Break 10:30 – 11:00

Basin, central Italy): Biostratigraphy and discussion of Aptian–Albian bioevents

Session Two – Nannos in the Age of the

16:45 – 17:00
Talk 18: Granero et al. – Morphometric analysis

Dinosaurs – Cretaceous (continued)of the calcareous nannofossil group Aspidolithus in

11:00 – 11:15
Talk 26: Tangunan et al. – Multivariate evaluation

the lower Campanian: Implications for taxonomy

rubric for assessing the reliability of Cretaceous
nannofossil index taxa and bioevents

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11:15 – 11:30
Talk 27: Miniati et al. – Revised calcareous nan-

14:45 – 15:00
Talk 36: Utsunomiya et al. – Evolutionary change

nofossil biostratigraphy and chemostratigraphy forin crystallographic orientation and morphology ofthe late Turonian–early Campanian at Seaford Head

Cenozoic coccoliths: Insights from Toweius, Reticu-(southern England)

lofenestra, and Umbilicosphaera

11:30 – 11:45
Talk 28: Marconato et al. – Orbitally paced bot-

Coffee Break 15:00 – 15:30

tom-water acidification episodes linked to the late
Maastrichtian warming event: Calcareous nanno-Workshops 15:30 – 17:30 (four options – sign up

fossil evidence in the Hor Hahar section, Israel

required)

11:45 – 12:00
Talk 29: Chira et al. – Integrated biostratigraphy of

1. Biostratigraphy Software – StrataBugs (Paulthe Upper Cretaceous–Eocene deposits from Poiana

BugWare)Botizei-Botiza (Maramures, Romania)

2. Jurassic Nannofossils (Fabienne Giraud, Uni-

12:00 – 12:15
Talk 30: Wang et al. – Cretaceous–Paleogene cal-versité Grenoble Alpes; Jason Jeremiah, Viridien;careous nannofossils and their biostratigraphic and

Lyon 1)

paleoceanographic implications in southern Tibet

3.

12:15 – 12:30
Talk 31: Vallejo-Hincapié – Cretaceous and Ce-(Jeremy Young, University College London)

nozoic calcareous nannofossil biostratigraphy of theDunkley Jones, University of Birmingham)

Britton, StrataData) & BugWin (Mitch Covington,

Emanuela Mattioli, Université Claude Bernard
ExtantCoccolithophore

Biogeography

4. Geochemical Proxies from Coccoliths (Tomnorthwestern inland basins of Colombia
Mid-Conference Fieldtrip (1) 18:00 – 20:00
Lunch break (lunch provided) 12:30 – 13:30

Mini field trip to The Great Orme, Llandudno (Peter
Lucas, PetroStrat)

Session Three – “Hwyl Fawr T-Rex; Bore Da
Paleogene” – Paleogene Nannos

Wednesday 11th September 2024

Chairs: Boris Karatsolis & Andrea Pardon

Session One – “Everyone say wayo – E–O” –13:30 – 14:00
Keynote 3 (Talk 32): Bown et al. – What drove

Oligocene to Miocene Nannos

nannoplankton evolution and community dynamics

09:00 – 09:15
Talk 37: Viganò & Agnini – Unlocking the mysterythrough the Paleogene?

Chairs: Luc Beaufort & Deborah Tangunan

14:00 – 14:15
Talk 33: Chouar et al. – Stratigraphy of the low-of Clausicoccus subdistichus across the Eocene–er Danian in the Danish Basin: Perspectives from

09:15 – 09:30
Talk 38: Jordan et al. – The search for fossil

calcareous nannofossils and stable isotopes
14:15 – 14:30
Talk 34: Wang – Late Paleocene eastern Tethys pa-

Oligocene transition

siliceous haptophytes

leoenvironmental reconstruction using calcareous

09:30 – 09:45
Talk 39: Routledge et al. – Evaluating Oligocene

nannofossils in the Patala Formation, Salt Range,

calcareous nannoplankton diversity and commu-

Pakistannity dynamics

14:30 – 14:45
Talk 35: Pige et al. – Temperature-dependent cal-

09:45 – 10:00
Talk 40: Su et al. – Calcareous nannofossil changes

careous nannofossil exported productivity during

in reddish-brown sediments in the abyssal South

early Paleogene hyperthermals

China Sea during the Oligocene–MioceneINA19910:00 – 10:15
Talk 41: Karatsolis et al. – Oligocene to Recent

Workshops 15:30 – 17:30 (four options – sign up

North Atlantic biostratigraphy and calcareous nan-

1. Cretaceous Nannofossils (Paul Bown, Univer-

nofossil assemblages (IODP Expedition 395)sity College London; Matthew Hampton, Network

10:15 – 10:30
Talk 42: Holcová & Scheiner – Calcareous nan-

Stratigraphic; Richard Howe, Ellington Geologicalnoplankton and εNd as paleogeographic proxies: A

2. Public Outreach (Mario Cachão, Universidade

case study from the Langhian junction of the Indiande Lisboa; Micaela Chaumeil Rodriguez, Instituto de

Ocean, the Mediterranean, and the Paratethys

Investigación en Paleobiología y Geología; Mariem

10:30 – 10:45
Talk 43: Puentes-Jorge et al. – Middle to Late

Saavedra-Pellitero, University of Portsmouth; Deb-

Miocene calcareous nannoplankton biostratigraphy

3. Understanding Molecular Genetic Data – (Eland paleoecology at Broken Ridge, eastern Indian

Mahdi Bendif, Université du Québec à Rimouski)

Ocean (ODP Site 752)

4. AI (Artificial Intelligence) and Automatedrequired)Services)orah Tangunan, University College London)

Coccolith Identification (Luc Beaufort, CEREGE)
Coffee Break 10:45 – 11:15
Conference Dinner 18:00 – 23:59
Session Two – “Take a Chill Pill” – Neogene

3-course dinner at Dylan’s Llandudno followed by

Nannosdancing (Twmpath band – Twmpathology)

11:15 – 11:45
Keynote 5 (Talk 44): Bendif – Comparative ge-

Thursday 12th September 2024

nomics of the Isochrysidales

Session One – “Blowing hot and cold” –11:45 – 12:00
Talk 45: Skampa et al. – Early Pliocene calcareous

Nannos in the Ice Agenannofossils contribute to the paleoceanographic

Utsonomiya

reconstruction of the Cretan Basin (southern Ae-

09:00 – 09:30
Keynote 4 (Talk 48): Bolton et al. – Last glacial togean Sea, NE Mediterranean)

Chairs:AlyssaPeleo-Alampay&

Masayuki

12:00 – 12:15
Talk 46: Lancis et al. – Structural developments

Holocene sedimentation patterns and coccolitho-

within the Family Ceratolithaceae

in response to South Asian monsoon strengthening

12:15 – 12:30
Talk 47: De Kaenel – A revision of Quaternary

09:30 – 09:45
Talk 49: Razmjooei et al. – Improving Arctic

species of the genus Scyphosphaera

Quaternary geochronology and paleoceanographic

phore dynamics in the northwestern Bay of Bengal

reconstructions using calcareous nannofossils
Lunch break (lunch not provided) 12:30 – 14:00

09:45 – 10:00
Talk 50: Wang et al. – Impact of the biological

Schools outreach session 13:00 – 15:00

carbon pump on atmospheric pCO2 over the past

(Running concurrently with poster session)

800,000 years

4×10–15 minute talks, microscope demonstration,

10:00 – 10:15
Talk 51: Pedrão et al. – Coccolith dynamic distri-posters, talk to scientists

bution in the western tropical Atlantic during the
Poster Session (1) 14:00 – 15:30

last 300,000 years: Toward a better understanding(Running concurrently with schools outreach ses-of oceanic current dynamics

sion)

10:15 – 10:30
Talk 52: Saavedra-Pellitero et al. – Particulate

Coffee Break 15:00 – 15:30

inorganic carbon in the Pacific sector of the South-

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ern Ocean: Satellite measurements versus cocco-

ity of alkenone and calcareous nannofossil abun-lithophore estimatesdance records across the southeastern Philippines:
Insights on alkenone production and paleoceano-

Coffee Break & Poster Session (2) 10:30 – 11:30

graphic reconstructions

Session Two – “Life on the Ocean Wave” –15:00 – 15:15
Talk 62: Cachão & Carvalho – Not a source ofExtant Nannos

atmospheric CO2…

11:30 – 11:45
Talk 53: Bronzo et al. – Paleoclimatic reconstruc-

Coffee Break 15:15 – 15:45

tion of the past 28 kyr BP based on calcareous nannofossil assemblages in the Ligurian Sea

Session Four – Awards, INA business/AGM

11:45 – 12:00
Talk 54: Frada et al. – Phosphate-limiting condi-

Chairs: Simon Cole & Emanuela Mattioli

tions induce cell volume increase in natural cocco-

15:45 – 17:45
Including INA20 (2026) bids and votes. Close.

lithophore populations
12:00 – 12:15
Talk 55: González-Martín et al. – Environmen-

Mid-Conference Fieldtrip (2) 18:00 – 20:00

tal influences on coccolithophore distribution andLucas, PetroStrat)

abundance in the water column of the western Iberian margin (August 2022)

Mini field trip to The Great Orme, Llandudno (Peter

Friday 13th to Sunday 15th September 2024

12:15 – 12:30
Talk 56: Wang et al. – Calcification response of

Post-conference field trip - Snowdonia (Eryri)

Emiliania huxleyi to temperature and pH variations

Friday – Slate; Llanberis, Zip World Deep Mine

under calcitic and aragonitic sea conditions

Tour (Llechwedd), (Jonathan Wilkins, X-ray Mineral

12:30 – 12:45
Talk 57: Bianco et al. – When CO2 increases, how

Services [retired]).

does Helicosphaera carteri respond?

(Clogau); Harlech, Mochras Borehole and Mawd-– 2 nights residential (Barmouth)

Saturday – North Wales Nannofossils & Golddach Estuary (Dylan Roberts & Hannah Torrance,

Lunch break (lunch provided) 12:45 – 13:45

PetroStrat).
Sunday – Barmouth; Porthmadog (Portmeirion Vil-

Session Three – Tessellation, identification,
calcification, precipitation
Chairs: Jelena Godrijan & Mohammad Razmjooei
13:45 – 14:15
Keynote 6 (Talk 58) Hagino – Recent progress inthe studies of Braarudosphaera bigelowii
14:15 – 14:30
Talk 59: Bazzicalupo et al. – Coccolithophore
response to marine alkalinization: The results ofocean alkalinity enhancement exposure
14:30 – 14:45
Talk 60: Wheeler – Understanding the specialised
cellular mechanisms that support calcification incoccolithophores
14:45 – 15:00
Talk 61: Padre et al. – Spatio-temporal variabil-lage/Ffestiniog Railways); Caernarfon Castle.

INA19Posters11

ny; Nussdorf section, Austria)

P-01: Álvarez et al. – Changes in productivity in

P-11: Fujiyama et al. – Early Miocene microfossils

the Guaymas Basin over the last 22,000 years:

from Marmorito (Italy)

Insights from coccolithophores in sediments fromIODP Site U1549

P-12: Gholamifard et al. – Early Aptian Oceanic Anoxic Event 1a (OAE1a): Evidence based on

P-02: Archontikis et al. – Recovery and diversi-

calcareous nannofossils in the Qaleh Zoo section,

fication of coccolithophores after the Cretaceous/

centra Kopet Dagh, Iran

Paleogene boundary mass extinction, IODP Expedition 392, the Agulhas Plateau

P-13: González-Martín et al. – Coccolithophore
assemblages and paleoceanographic dynamics at

P-03: Argenio et al. – Paleoceanographic and pa-

IODP Site U1385: Insights from the Pliocene–Pleis-

leoclimatic changes during the Quaternary at IODP

tocene transition (western Iberian margin)

Site U1586, Iberian marginP-14: Howe – Ultrastructure and taxonomy of the
P-04: Asanbe & Henderiks – Biometric analysis

Families Axopodorhabdaceae and Cretarhabdaceaeof the genus Toweius across the Early Eocene Climatic Optimum (EECO, ~53–49 Ma) at ODP Site

P-15: Howe – Ultrastructure and taxonomy of the1258, Demerara Rise

Order Arkhangelskiales

P-05: Bonatelli et al. – The uncultivated side of

P-16: Jin & Liu – Estimating the coccolithophore

coccolithophores: Digging into the organic matterratio of particular inorganic carbon to particulateorganic carbon from the geometry of living cells

P-06: Bronzo et al. – Calcareous nannofossil assemblages as evidence of shifts in the Arctic/Polar

P-17: Jordan et al. – The search for fossil siliceous

Fronts during the past 24 kyr BP along the Westhaptophytes

Spitsbergen margin
P-18: Lancis et al. – Ceratolithaceae biostratigraP-07: Calvelo et al. – Preliminary results of calcar-

phy of ODP Hole 999A, Caribbean Sea

eous nannofossil analyses of Neogene and Quaternary units in northwestern Pangasinan, Philippines

P-19: Lancis et al. – Ceratolithaceae biostratigraphy of ODP Site 1237, equatorial PacificP-08: Catelli et al. – Gradual phyletic evolution of
Reticulofenestra oamaruensis from Reticulofenestra

P-20: Liu & Sun – The relationship between theclatrata: A rare example of calcareous nannoplank-

carbonate counter pump and seawater CO2 in the

ton microevolution preserved in the sedimentary

middle Miocene

record at IODP Site U1553 (southern Pacific Ocean)P-21: Ma & Liu – A decreased carbonate pump
P-09: Chouar & Thibault – Biometric analysis ofduring the Oligocene–Miocene transition: Regulat-

Maastrichtian Arkhangelskiella group in the Indianing the oceanic buffer capacity

Ocean (ODP Hole 762C): Taxonomy and evolution
P-22: Mahanipour et al. – Evidence of the midP-10: Ćorić et al. – Calcareous nannofossils at the

Valanginian Weissert Event in the Zagros Basin in

Cretaceous/Paleogene boundary of the Northern

Iran based on calcareous nannofossils and carbon

Calcareous Alps (Wasserfallgraben section, Germa-isotope data

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P-23: Mahanipour & Nejadsahebi – Evidence of

P-33: Rigual Hernández et al. – Evolution of coc-

Discoaster multiradiatus size variation in the latecolithophore communities in the Atlantic Iberian

Paleocene–early Eocene of the Zagros Basin (SWmargin during the Common Era

Iran)
P-34: Rigual Hernández et al. – Response of theP-24: Malavolta et al. – Distribution and diversity

coccolithophore Calcidiscus leptoporus to environ-of coccolithophore communities living in the tropi-

mental change during the industrial era in the Sub-

cal and subtropical South Atlantic: Preliminary re-antarctic Southern Ocean

sults from AMT28
P-35: Rivas et al. – Pleistocene–Holocene calcareP-25: Malinverno et al. – Coccolithophore sea-ous nannofossils and foraminifera from the Argen-sonal export production and fluxes in the Ioniantine Continental Margin, southwest Atlantic Ocean

Sea, eastern Mediterranean (June 2004–September 2005)

P-36: Routledge et al. – Calcareous nannofossils from the Paleocene–Eocene Thermal Maximum,

P-26: Marconato et al. – Size and morphological

IODP Site U1557, South Atlantic Oceanchanges in Coccolithus pelagicus across the Danianand their link to environmental recovery from the

P-37: Self-Trail et al. – Preliminary biostratigra-

K/Pg mass extinction in the SE Tethys, Israel

phy of the lower Cenomanian Buda Limestone fromthe U.S. Geological Survey GC-3 and GC-5 cores,

P-27: Martín-García et al. – Reconstruction of the

Texas, USA

ocean surface dynamics of the Iberian margin in
the Miocene–Pliocene using calcareous nannofossil

P-38: Sheldon et al. – Early to Middle Miocene

assemblages

nannofossils from the Valhall–Hod area, NorwegianNorth Sea

P-28: Murphy et al. – Drivers of Neogene coccolithophore macroevolution

P-39: Srivastava et al. – Responses of calcareous
nannoplankton to mid-Pliocene dynamics between

P-29: Palandri et al. – Leveling the gap between

climate and the carbon cycle in the North Atlantic

different counting techniques in coccolithophore
culturesP-40: Stoykova & Ivanov – Early Eocene hyperthermals in northern Bulgaria (SE Europe): New

P-30: Penales et al. – Coccolithophore assemblage

nannofossil and stable isotope data

dynamics and Emiliania huxleyi morphological patterns during the years 2017–2019 in the Aegean

P-41: Stoykova et al. – Calcareous nannofossil

Sea (Greece, NE Mediterranean)

response to the early Oligocene Rhodope volcanic
eruptions in some central and eastern Paratethyan

P-31: Pérez Panera et al. – Insights into the lastbasins: A comparison

glacial–interglacial shift: Microfossils and geochemical evidence from the Argentine Continental MarginP-42: Triantaphyllou et al. – Investigating the size
variability and coccolith mass of Emiliania huxleyi in

P-32: Righi et al. – Study of the paleoclimatic

the Aegean Sea (NE Mediterranean): 20 years oftransition from Greenhouse to Icehouse conditions

evidence on modern assemblages compared to theby means of calcareous nannofossils in the South-

last two thousand years

ern, Atlantic, Pacific, and Indian Oceans
P-43: Utsunomiya et al. – Paleocene–Eocene cal-

INA1913

careous nannofossil biostratigraphy of the SurpriseP-46: Vitsou et al. – Confocal laser imaging of cal-Hill core from Virginia, USA

careous nannofossils

P-44: Viganò & Agnini – Mediterranean marine

P-47: Winter et al. – A high-resolution depth pro-sediment core database: Unlocking paleoclimate

file of coccolithophores from oligotrophic waters insignals for the last 20,000 years

the North Atlantic Gyre (part 2)

P-45: Visentin et al. – Early and Middle Jurassic

P-48: Xi et al. – Paleocene to Eocene calcareous

Tethyan calcareous nannofossil zonation: Taxonom-

nannofossil zonation in the western Tarim Basin,

ic updates and biostratigraphic improvements

Central Asia

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Changes in productivity in the Guaymas Basin over the last
22,000 years: Insights from coccolithophores in sedimentsfrom IODP Site U1549
María-Carmen Álvarez

Universidad Nacional Autónoma de México, Instituto de Geofísica; Consejo Nacional de Humanidades, Ciencias y Tecnologías (CONAHCYT),Mexico City, Mexico; malvarez@igeofisica.unam.mx

Ligia Pérez-Cruz, Jaime Urrutia-Fucugauchi

Universidad Nacional Autónoma de México, Instituto de Geofísica, Mexico City, Mexico; perezcruz@igeofisica.unam.mx; juf@igeofisica.unam.mx

Alejandro Aldama-Cervantes, Mauricio Velázquez Aguilar
Universidad Nacional Autónoma de México, Posgrado en Ciencias del Mar y Limnología, Mexico City, Mexico;alejandro.aldama.cervantes@ciencias.unam.mx; maps.vlo@ciencias.unam.mx

Mariem Saavedra-Pellitero

University of Portsmouth, School of the Environment, Geography and Geosciences, Portsmouth, PO1 3QL, UK; mariem.saavedra-pellitero@port.ac.uk

https://doi.org/10.58998/jnr3200
The Guaymas Basin in the central Gulf of California is a very productive area with high chlorophyll a concentrations
in some parts of the basin. Coastal upwelling, which develops yearly on the eastern coast, is strong, and the resulting
eddy circulation promotes phytoplankton growth throughout the gulf. These processes are induced by the atmospheric
dynamics of the Gulf of California and the prevailing northern winds blowing along the continental coast during springwinter. Coccolith abundance and net primary productivity (NPP) have been reconstructed for the last 22,000 years,
using sediment samples that were retrieved from International Ocean Discovery Program (IODP) Expedition 385 HoleU1549A (27°28.33167'N, 111°28.7844'W). Site U1549 was drilled at a water depth of 1840 m aboard the R/V JOIDES
Resolution, with Hole U1549A drilled to a total depth of 168.0 m below the seafloor, recovering 166.89 m of core, of
which the uppermost 40 m were studied.
The coccolith assemblage from the cores of Hole U1549A is dominated (>50%) by Gephyrocapsa >3 µm and thereconstructed NPP is high with values ranging from 944.66 to 1288.25 mg C/m2/day. Variations in the coccolith abundance and the NPP allowed us to identify four scenarios.
(1) Cold and productive: The highest NPP values were recorded during the Last Glacial Maximum and Heinrich
Event 1 (H1). The genus Gephyrocapsa >3 µm showed its highest abundances and Coccolithus pelagicus subsp.
braarudii was present in relatively high numbers. Both taxa developed well under upwelling conditions withcool water temperatures.
(2) Intermittent stratification: A stepwise decrease of NPP occurred in the Bølling-Allerød Interstadial (BA) and
Younger Dryas (YD). Coccolithus pelagicus subsp. braarudii showed a decline in abundance, whereas Florisphaera profunda showed an increase. Variability and intermittent stratification characterized these intervals.
Minimum values in total abundance, NPP, and most of the taxa were reached at 11,707 cal yr BP.
(3) Warm conditions with occasional stratification: At the beginning of the Holocene Climatic Optimum, C. pelagicus subsp. braarudii disappeared, and abundant warm-water taxa dominated. After this abundance peak, adecrease in NPP took place, and stratification events are suggested by the presence of F. profunda.
(4) Stratified waters: There was a general progressive decrease in NPP that characterized the modern part of therecord, and the variable presence of F. profunda revealed stratification in the surface waters.

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Calcareous nannofossils of the Valanginian/Hauterivian
boundary interval in the Romanian Carpathians
Eliza Anton

National Institute of Marine Geology and Geo-Ecology (GeoEcoMar), Bucharest, Romania; antoneliza@geoecomar.roMihaela Melinte-Dobrinescu

National Institute of Marine Geology and Geo-Ecology (GeoEcoMar), Bucharest, Romania; University of Bucharest, Faculty of Geology andGeophysics, Bucharest, Romania; melinte@geoecomar.rohttps://doi.org/10.658998/jnr3201
We studied the Cretaceous calcareous nannofossils in a succession of 15 m-thick dark gray to black marlstones, interbedded with centimeter- to decimeter-thick calcareous sandstones, that crop out in the Romanian Carpathian bend area.
Forty-five samples were investigated qualitatively and semiquantitively. The calcareous nannofossil assemblages wereassigned to the NC4 nannofossil zone of Roth (1983), including Subzones NC4a and NC4b of Bralower et al. (1995),
which were separated on the basis of the first occurrence (FO) of Lithraphidites bollii.
The calcareous nannofossil preservation is moderate to good, which is supported by the abundance of Watznaueria
barnesiae that reaches up to 28% of the total assemblage. Nannoconids are the second most abundant nannofossil taxa
(up to 20%), and they show significant species diversity that includes Nannoconus bermudezii, N. bonetii, N. bronnimannii, and N. steinmannii. In addition to W. barnesiae and the nannoconids, commonly identified taxa are Micrantholithus hoschulzii, M. obtusus, Retecapsa spp., Cretarhabdus spp., Conusphaera spp., Biscutum constans, Discorhabdus
ignotus, Manivitella pemmatoidea, Staurolithites stradneri, Cruciellipsis cuvillieri, Cyclagelosphaera brezae, C. margerelii, C. deflandrei, Zeugrhabdotus embergeri, and Haqius circumradiatus. In the studied section, several nannofossil events were encountered that are listed in stratigraphic succession: last occurrences (LO) of Rucinolithus wisei, R.
pinnatus, and Eiffellithus windii, FOs of Diloma galiciense, L. bollii, and Tegulalithus septentrionalis. The calcareous
nannofossil assemblages in the studied succession exhibit similarities with the La Charce section, Vocontian Basin, SE
France, which is the Global Boundary Stratotype Section and Point (GSSP) for the base of the Hauterivian Stage (Mutterlose et al., 2021), where the last four above-mentioned events were found in the lowermost Hauterivian, whereas the
LO of R. wisei, followed by the LO of R. pinnatus, occur in the uppermost Valanginian.
References:
Bralower, T.J., Leckie, R.M., Sliter, W.V. & Thierstein, H.R. 1995. An integrated Cretaceous microfossil biostratigraphy. In: Geochronology, Time
Scales and Global Stratigraphic Correlation. SEPM Special Publication, 54: 65–79.
Mutterlose, J., Rawson, F.P. & Reboulet, S. 2021. The Global Boundary Stratotype and Point (GSSP) for the base of the Hauterivian Stage (Lower
Cretaceous), La Charce, southeast France. Episodes, 44: 129–130. https://doi.org/10.18814/epiiugs/2020/020072
Roth, P.H. 1983. Jurassic and Lower Cretaceous calcareous nannofossils in the western North Atlantic (Site 534): biostratigraphy, preservation, and some observations on biogeography and paleoceanography. Initial Reports of the Deep Sea Drilling Project, 76: 587–621.
https://doi.org/10.2973/dsdp.proc.76.125.1983

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Recovery and diversification of coccolithophores after the
Cretaceous/Paleogene boundary mass extinction, IODP
Expedition 392, the Agulhas Plateau
Odysseas A. Archontikis

University of Oxford, Department of Earth Sciences, Oxford OX1 3AN, UK; The Natural History Museum, Department of Earth Sciences, London
SW7 5BD, UK; University College London, Department of Earth Sciences, London, WC1E 6BT, UK; odysseas.archontikis@univ.ox.ac.uk

Paul R. Bown

University College London, Department of Earth Sciences, London, WC1E 6BT, UK; p.bown@ucl.ac.uk

Jens O. Herrle

Goethe-University Frankfurt, Institute of Geosciences, 60438 Frankfurt am Main, Germany; jens.herrle@em.uni-frankfurt.de

Denise K. Kulhanek

Christian-Albrechts-University of Kiel, Institute of Geosciences, 24118 Kiel, Germany; denise.kulhanek@ifg.uni-kiel.deThomas Westerhold

University of Bremen, MARUM - Center for Marine Environmental Sciences, Bremen, Germany; twesterhold@marum.de

Jeremy R. Young

University College London, Department of Earth Sciences, London, WC1E 6BT, UK; jeremy.young@ucl.ac.uk

Steve M. Bohaty

Heidelberg University, Institute of Earth Sciences, 69120 Heidelberg, Germany; steve.bohaty@geow.uni-heidelberg.de

IODP Expedition 392 Scientists
https://doi.org/10.58998/jnr3202
The Cretaceous/Paleogene (K/Pg) boundary (66 Ma) was a pivotal moment in Earth’s history when one of the most severe mass extinction events occurred. The bolide impact that triggered this event not only affected terrestrial ecosystems
but also had profound effects on the marine biota, biological pump, and global carbon cycle, as is evidenced by community data, diversity records, and geochemical proxies. Calcareous nannoplankton are a key component of the modern
global carbon cycle and one of the most important groups of marine primary producers with a key role in sedimentformation that stretches back 200 million years. The K/Pg event is associated with the eradication of approximately 90%
of Cretaceous nannoplankton species, and post-extinction lineages are characterized by their remarkably small sizes (<3μm coccolith length) and mixotrophic strategies (Gibbs et al., 2020).
Here, we present data on high-latitude fossil coccolithophore assemblages across a recently recovered K/Pg sectionthat was collected at International Ocean Discovery Program (IODP) Site U1579, drilled on the central Agulhas Plateau
during IODP Expedition 392 (Uenzelmann-Neben et al., 2023). The K/Pg interval was initially identified during the
expedition by a change in sediment color, magnetic susceptibility, and diagnostic calcareous nannofossil assemblages.
We conducted quantitative abundance analyses on the post-K/Pg newly originated calcareous nannofossil lineages,
including those that form a series of acmes (genera Praeprinsius, Prinsius, and Toweius), and determined the tempo of
Paleocene coccolithophore evolutionary dynamics in the high latitudes. In addition, we used high-resolution calcareous
nannofossil biostratigraphy to confirm the presence of the K/Pg boundary interval and bulk carbon and oxygen isotope
records to provide a refined age model for correlation with other published Paleocene nannofossil records. These newdata provide additional insights into the processes of Danian plankton recovery, biogeographic trends in the high latitudes, and the establishment of marine ecological niches after the mass extinction.
Acknowledgements:

This work was supported by the UK Natural Environment Research Council [grant number NE/W009854/1] to OAA.

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References:
Gibbs, S.J., Bown, P.R., Ward, B.A., Alvarez, S.A., Kim, H., Archontikis, O.A., Sauterey B., Poulton, A.J., Wilson, J. & Ridgwell, A. 2020.
Algal plankton turn to hunting to survive and recover from end-Cretaceous impact darkness. Science Advances, 6(44): eabc9123.
https://doi.org/10.1126/sciadv.abc9123
Uenzelmann-Neben, G., Bohaty, S.M., Childress, L.B., Archontikis, O.A., Batenburg, S.J., Bijl, P.K., Burkett, A.M., Cawthra, H.C., Chanda, P., Coenen,
J.J., Dallanave, E., Davidson, P.C., Doiron, K.E., Geldmacher, J., Gürer, D., Haynes, S.J., Herrle, J.O., Ichiyama, Y., Jana, D., Jones, M.M., Kato,
C., Kulhanek, D.K., Li, J., Liu, J., McManus, J., Minakov, A.N., Penman, D.E., Sprain, C.J., Tessin, A.C., Wagner, T. & Westerhold, T. 2023.
Expedition 392 summary. Proceedings of the International Ocean Discovery Program, 392. https://doi.org/10.14379/iodp.proc.392.101.2023

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Paleoceanographic and paleoclimatic changes during the
Quaternary at IODP Site U1586, Iberian margin
Carmen Argenio

University of Sannio, Benevento, Italy; argenio@unisannio.it

José-Abel Flores

Universidad de Salamanca, Department of Geology, 37008, Salamanca, Spain; flores@usal.es

Barbara Balestra

American University, Department of Environmental Science; National Museum of Natural History, Washington, DC, USA; balestra@american.edu

Filomena Ornella Amore

University of Sannio, Benevento, Italy; f.amore@unisannio.it

IODP Expedition 397 Scientists
https://doi.org/10.58998/jnr3203
This study presents calcareous nannoplankton data from the North Atlantic area. Many climate studies currently focus
on this region, particularly on the Iberian margin. Due to its high sedimentation rate, sedimentary records offer the possibility to perform high-fidelity and high-resolution climate variability studies along the Iberian margin. Our analyses
are centered on Site U1586 (37º37.283’N, 10º42.628’W; 4691 m below sea level), which was drilled during the International Ocean Discovery Program (IODP) Expedition 397 along the SW Iberian margin. The CEX dissolution index
was calculated, and it suggests good preservation for the coccolith assemblages. Abundance percentage variability of
selected coccoliths is also provided to highlight paleoproductivity and paleotemperature changes. The main results provide information on global climate evolution and changes in paleoceanography and coccolithophore productivity related
to upwelling strength fluctuations in surface-water masses and subtropical gyre dynamics.

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Biometric analysis of the genus Toweius across the Early
Eocene Climatic Optimum (EECO, ~53–49 Ma) at ODP Site
1258, Demerara Rise
Joseph Asanbe

Uppsala University, Department of Earth Sciences, Uppsala, Sweden; joseph.asanbe@geo.uu.se

Jorijntje Henderiks

Uppsala University, Department of Earth Sciences, Uppsala, Sweden; Jorijntje.Henderiks@geo.uu.se

https://doi.org/10.58998/jnr3204
The genus Toweius represents a prominent group of coccolithophores during the late Paleocene and early Eocene thatis known for its evolutionary linkage and abundance turnover to Reticulofenestra during the Early Eocene Climatic
Optimum (EECO). Typically, Toweius coccoliths exhibit elliptical to circular shapes with a central area comprisingconjunct nets or bars and a distinctive architecture that features three concentric tubes (inner, middle, and outer) alongwith proximal and distal shields. However, the discovery of a small morphotype (termed herein Toweius sp. II) from thetropics, which lacks the typical inner and middle R-units, raises important questions about the origin and evolutionary
significance of this taxon.
This study investigated the biometric and morphological variation in Toweius across the EECO at Ocean Drilling
Program (ODP) Site 1258, focusing on defining the small morphotype and exploring its relationship with other Toweius
species. Observations using light microscopy (LM) and scanning electron microscopy (SEM) revealed that the absenceof a central tube, along with a circular shape and wide central opening, was present in nearly all specimens of Toweius sp.
II. A biometric analysis indicated that Toweius sp. II exhibits a unimodal size distribution with a range of 2.25–3.4 µm
and an average of 2.65 µm, distinctly smaller than the medium-sized Toweius (3.2–5.4 µm) that dominated early EECO
assemblages. Similarly, other metrics, such as coccolith aspect ratio, central diameter to total length ratio, and circularity
index, further distinguish Toweius sp. II from other members of the genus.
While the observed biometric disparity could be attributed to a preservation bias, Toweius sp. II likely derived froma Toweius species of similar size. The consistent presence of this taxon throughout early and peak EECO times suggeststhat dissolution may not have been significant. As such, this taxon probably represents either a state of malformation in
calcification or an actual ecophenotypical variant of Toweius with a restricted occurrence in the tropics. In conclusion,
the distinct biometric features and lower coccolith mass of Toweius sp. II point to decreased calcification and possibly an
ecological adaptation that may have facilitated its persistence much longer within the EECO than other Toweius species.

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From alkenones to Cretaceous marine Isochrysidales tococcoliths
Marie-Pierre Aubry

Rutgers University, Department of Earth and Planetary Sciences, New Brunswick, New Jersey 08854, USA; aubry@eps.rutgers.edu

Weimin Si

Brown University, Department of Earth, Environmental, and Planetary Sciences, Providence, Rhode Island 02912, USA; weimin_si@brown.edu

Luc Beaufort

CEREGE, Technopole de l’Arbois 13090 Aix-en-Provence, France; beaufort@cerege.fr

Fabienne Giraud

Université Grenoble Alpes, Université Savoie Mont Blanc, CNRS, IRD, IFSTTAR, ISTerre, 38000 Grenoble, France;
fabienne.giraud-guillot@univ-grenoble-alpes.fr

Ruigang Ma

Tongji University, State Key Laboratory of Marine Geology, Shanghai 200092, China; maruigang@tongji.edu.cn

Ekaterina Shcherbinina

Geological Institute of the Russian Academy of Sciences, Moscow 119017, Russia; katuniash@gmail.com

Joseph B. Novak

University of California Santa Cruz, Ocean Sciences Department, Santa Cruz, California 95064, USA; jobnovak@ucsc.edu

Nora RichterRoyal Netherlands Institute for Sea Research (NIOZ), Department of Marine Microbiology and Biogeochemistry, 1790 AB Den Burg, Netherlands;
nora.richter@nioz.nl

Pratigya Polissar

University of California, Santa Cruz, Ocean Sciences Department, Santa Cruz, California 95064, USA; polissar@ucsc.edu

Timothy D. Herbert

Brown University, Department of Earth, Environmental and Planetary Sciences, Providence, Rhode Island 02912, USA; timothy_herbert@brown.edu

https://doi.org/10.58998/jnr3205
Living coccolithophore communities are dominated by a small group of marine species of the genera Emiliania andGephyrocapsa. They have an unambiguous marine record back to the early Eocene when Reticulofenestra evolved. All
three genera belong to the Family Noelaerhabdaceae in the Order Isochrysidales. The current consensus among the nannoplankton community is that there were no calcifying marine Isochrysidales in the Mesozoic (Henderiks et al., 2022),
despite taxonomic evidence (Black, 1975; Covington & Wise, 1987), molecular evidence (Medlin et al., 2008; Liu etal., 2010), and alkenone data (Brassell, 2014; Hasegawa & Goto, 2024) suggestive of Cretaceous occurrences. Of thesethree sources of information, the biomarker is structurally unique and stable over geological time, and it holds the best
potential for an unambiguous demonstration of the presence of alkenones in Cretaceous sediments identical to those
known from Holocene coretop sediments, as well as cultures of Emiliania huxleyi and Gephyrocapsa oceanica. Thus,
it can be used as a fingerprint for identifying the occurrence of Isochrysidales in marine sediments even if the calcite
skeleton is not produced or not preserved. The molecular profile of alkenones can also be lineage-specific and provide
clues of Isochrysidales evolution.
Our recent investigation (Si et al., 2024) of hemipelagic sediments from the Hauterivian through Santonian (130–80
Ma) that are broadly distributed in the Atlantic Basin has yielded abundant and diverse alkenones among which arethose specific to marine Isochrysidales. From this we have concluded that mostly unsuspected coccolith-bearing species
in this order synthesized alkenones already by ~132 Ma. This has important implications. From an evolutionary perspective, this implies that the Cenozoic Family Noelaerhabdaceae is directly rooted in a genetic stock of Mesozoic
Isochrysidales ancestors. We have undertaken a search for these ancestral coccoliths, based on the structural and opticalcharacters found in Noelaerhabdaceae, aware that these early morphotypes may depart markedly from the crown taxa,

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and focused our attention on the genera Repagulum and Pickelhaube. From a paleoclimatic perspective, the associationof alkenone C37:2 and inferred Isochrysidales species has led us to an estimated pCO2 in the range of 548–4090 ppm(median of 908 ppm) during the warm Cretaceous.
References:
Black, M. 1975. British Lower Cretaceous coccoliths. I. Gault Clay, part 2. Palaeontographical Society Monographs, 127: 49–112. https://doi.org/1
0.1080/25761900.2022.12131729
Brassell, S.C. 2014. Climatic influences on the Paleogene evolution of alkenones. Paleoceanography, 29: 255–272. https://doi.
org/10.1002/2013PA002576
Covington, J. & Wise Jr, S. 1987. Calcareous nannofossil biostratigraphy of a Lower Cretaceous deep sea fan complex: DSDP Leg 93, Site 603,
lower continental rise off Cape Hatteras, USA. Initial Reports of the Deep Sea Drilling Project, 93: 617–660. https://doi.org/10.2973/dsdp.
proc.93.116.1987
Hasegawa, T. & Goto, A.S. 2024. Paleoceanographic importance of tri-and di-unsaturated alkenones through the early phase of Cretaceous Oceanic Anoxic Event 2 from southern high latitudes of the proto-Indian Ocean. Organic Geochemistry, 188: 104722. https://doi.org/10.1016/j.
orggeochem.2023.104722
Henderiks, J., Sturm, D., Šupraha, L. & Langer, G. 2022. Evolutionary rates in the Haptophyta: Exploring molecular and phenotypic diversity. Journalof Marine Science and Engineering, 10: 798. https://doi.org/10.3390/jmse10060798
Liu, H., Aris-Brosou, S., Probert, I. & de Vargas, C. 2010. A time line of the environmental genetics of the haptophytes. Molecular Biology and Evolution, 27: 161–176. https://doi.org/10.1093/molbev/msp222
Medlin, L.K., Sáez, A.G. & Young, J.R. 2008. A molecular clock for coccolithophores and implications for selectivity of phytoplankton extinctions
across the K/T boundary. Marine Micropaleontology, 67: 69–86. https://doi.org/10.1016/j.marmicro.2007.08.007
Si, W., Novak, J.B., Richter, N., Polissar, P., Ma, R., Santos, E., Nirenberg, J., Herbert, T.D. & Aubry, M.P. 2024. Alkenone-derived estimates ofCretaceous pCO2. Geology, 52(7): 555–559. https://doi.org/10.1130/G51939.1

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Coccolithophore response to marine alkalinization: The resultsof ocean alkalinity enhancement exposure
Pietro Bazzicalupo

Università degli Studi di Milano-Bicocca, Dipartimento di Scienze Ambientali e della Terra, 20126 Milano, Italy; pietro.bazzicalupo@unimib.it

Arianna Azzellino, Eleonora Barbaccia

Politecnico di Milano DICA Department of Civil and Environmental Engineering, 20133 Milano, Italy;
arianna.azzellino@polimi.it; eleonora.barbaccia@polimi.it

Jose Gonzalez

Centro de Investigación Mariña da Universidade de Vigo, Estación de Ciencias Mariñas de Toralla (ECIMAT), Vigo, Spain; josegonzalez@uvigo.es

Pablo Serret

Centro de Investigación Mariña da Universidade de Vigo, Departamento de Ecoloxía e Bioloxía Animal, Vigo, Spain; pserret@uvigo.es

Paraskevi Pitta, Iordanis Magiopoulos

Hellenic Centre for Marine Research, Institute of Oceanography, Heraklion, Greece; vpitta@hcmr.gr; iordanis@hcmr.gr

Piero Macchi, Selene Varliero

Department of Chemistry, Materials and Chemical Engineering “Giulio Natta,” Politecnico di Milano, Milano 20131, Italy;
piero.macchi@polimi.it; selene.varliero@polimi.it

Filomena Romano

Hellenic Centre for Marine Research, Institute of Oceanography, Heraklion, Greece; mena.romano@hcmr.gr

Daniela Basso

Università degli Studi di Milano-Bicocca, Dipartimento di Scienze Ambientali e della Terra, 20126 Milano, Italy; CoNISMa, I-00196 Roma, Italy;
daniela.basso@unimib.it

https://doi.org/10.58998/jnr3206
Understanding phytoplankton adaptation to changing ocean conditions is paramount when investigating both fossil andpresent-day assemblages. Ocean alkalinity enhancement (OAE) is carbon dioxide removal (CDR) technology aimed
at increasing the ocean’s CO2 uptake capability by dispersing alkaline substances (e.g., Ca-hydroxide) on the ocean
surface. Investigating the response of coccolithophores to this technology within an OAE mesocosm experiment has
seldom been done, despite their potential effects on the ocean trophic chain and carbonate cycle.
Two sets of experiments were conducted where mesocosms were exposed to increasing concentrations of Ca-hydroxide slurry with two different trophic conditions and coccolithophore presences. These experiments took place at the
CIM-ECIMAT (Marine Research Centre of the University of Vigo, CIM UVIGO) and CretaCosmos (Hellenic Centre
for Marine Research, Crete) facilities. Coccolithophore assemblage composition and abundances were assessed throughoptical microscopic analysis of filtered mesocosms seawater. The results indicate that there is coccolithophore sensitivity to mesocosm confinement. Interestingly, a slightly positive correlation to low slurry concentration was observed,
whereas a high slurry concentration was detrimental to coccolithophore abundance. The same kind of response wasobserved in diatoms in experiments conducted in Crete, and a comparison with the diatom abundance patterns shows asimilarity between the two groups. Finally, a tentative coccolithophore morphological analysis was performed on somesamples. These findings could provide a baseline for understanding the potential adaptation of coccolithophores tochanges in ocean alkalinity.

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Artificial intelligence used for automatic detection of
calcareous nannofossils with SYRACOLuc Beaufort

Aix-Marseille University, CNRS, IRD, INRAE, CEREGE, 13090 Aix-en-Provence, France; beaufort@cerege.fr

https://doi.org/10.658998/jnr3207
Coccoliths are often found in great abundance in sediments, and a single microscopic field typically contains over 50 individuals. Biostratigraphic studies are facilitated when rare but diagnostic taxa can be observed. However, a few species
often dominate an assemblage, which complicates accurate counting. Achieving comprehensive counts presents challenges, including the risk of overlooking specimens or counting them multiple times. To obtain statistically significant
counts of entire coccolith assemblages, thousands of specimens must often be tallied. This makes the process impractical
if rare species need to be included in the statistics. To address this issue, some researchers restrict their counts to selecttaxa or use intricate logarithmic counting methods. Another solution is to develop an automated counting system. Artificial Intelligence (AI) aims to streamline the counting process, improve accuracy, and provide a more efficient meansof obtaining reliable data for coccolith analysis. Additionally, automated counting facilitates the cropping of coccolith
images for morphometric analyses of individual specimens.
In the mid-1990s, SYRACO (SYstème de Reconnaissance Automatique de COccolithes), an artificial coccolith classifier, was developed and has been used routinely for over twenty years. During this period of time, numerous advancements have occurred, both in the software, with the evolution of neural network architectures, and in the hardware, with
the increasing power and speed of computers that enable the processing of higher resolution images. There has also been
an improvement in the resolution and quality of digital cameras and optical methods that are used to capture coccolith
images. The emergence of polarization techniques now allows for cross-free and calibrated images, and the ability toroutinely capture multi-focus images. I will describe the evolution of these techniques and outline the current effective
protocol that can be rapidly implemented in laboratories for robust pattern recognition of the 28 coccolith classes mostabundantly found in Pliocene–Pleistocene sediments.							

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Comparative genomics of the Isochrysidales
El Mahdi Bendif

Université du Québec à Rimouski, Institut des sciences de la mer de Rimouski (ISMER), Rimouski, Canada; University of Oxford, Department ofEarth Sciences, Department of Biology, Oxford, UK; ElMahdi_Bendif@uqar.ca

https://doi.org/10.58998/jnr3208
Coccolithophores constitute one of the ecologically important phytoplankton groups, yet their evolutionary and diversity
patterns remain unclear due to limited observations. This is particularly true for the Order Isochrysidales, despite it containing several ecologically and economically key taxa, such as Gephyrocapsa huxleyi and Tisochrysis lutea. This study
provides a triptych overview of the relationships between Isochrysidales species by examining their macroevolutionary
phylogenetic context and conducting finer scale studies of intraspecific morphogenetic variability and biogeographic
structuring, as inferred from comparative genomics. First, obtaining a stable phylogenetic tree for all haptophytes using
single-gene phylogenies remains very challenging. Despite extensive sequencing efforts, several deep branches in the
haptophyte phylogenetic tree remain unresolved and statistically unsupported. For example, do the Isochrysidales form
an independent and basal divergence, or do they cluster with the Zygodiscales in the Calcihaptophycideae? To address
this, I propose employing a phylogenomic approach based on a large transcriptomic dataset that covers most of the haptophyte groups, although this may not necessarily resolve all nodes of haptophyte phylogeny. Second, the integrationof Isochrysidales diversity with recent genomic research has been successfully linked to the fossil record. This linkage
has been well demonstrated for the genus Gephyrocapsa, particularly at a fine scale for the species G. huxleyi. Suchstudies have provided insights into the evolutionary history and adaptive strategies of these organisms over geological timescales. Can similar analyses be extended to G. oceanica to uncover comparable patterns? Specifically, can we
identify evolutionary events in G. oceanica that correspond to changes observed in the fossil record? Additionally, what
can these findings reveal about the environmental factors that have influenced the evolution of G. oceanica, and how dothese factors compare to those affecting G. huxleyi? Third, to what extent do both G. oceanica and G. huxleyi differ interms of adaptability conferred by their genetic features? This question aims to explore the genetic basis of their adaptability to varying environmental conditions. What specific genes or genetic mechanisms contribute to the resilience orvulnerability of each species in different habitats? How do these genetic features influence their capacity to respond toenvironmental stressors such as ocean acidification, temperature fluctuations, and nutrient availability? Moreover, arethere differences in the ploidy levels or gene content between G. oceanica and G. huxleyi that explain their distinct adaptive strategies? Understanding these genetic differences can provide deeper insights into the evolutionary processes thatshaped the diversity and ecological success of these key phytoplankton species. Overall, this study sheds light on the
biocomplexity and microevolution of phytoplankton and highlights the importance of considering microdiversity whenstudying their ecological and biogeochemical roles in the global ecosystem.

INA19When CO2
respond?

increases,

how

does

25

Helicosphaera

carteri

Stefania Bianco

University School for Advanced Studies IUSS Pavia, 27100, Pavia, Italy; University of Pavia, Department of Earth and Environmental Sciences,
27100, Pavia, Italy; stefania.bianco@iusspavia.it

Manuela Bordiga

National Institute of Oceanography and Applied Geophysics of Trieste, 34010, Trieste, Italy; mbordiga@ogs.it

Gerald Langer

Universitat Autònoma de Barcelona (UAB), Institute of Environmental Science and Technology (ICTA), 08193 Bellaterra, Barcelona, Spain;
gerald.langer@uab.cat

Claudia Lupi, Andrea Di Giulio

University of Pavia, Department of Earth and Environmental Sciences, Pavia, Italy; claudia.lupi@unipv.it; andrea.digiulio@unipv.it

Patrizia Ziveri

Universitat Autònoma de Barcelona (UAB), Institute of Environmental Science and Technology (ICTA), 08193 Bellaterra, Barcelona, Spain;
Patrizia.Ziveri@uab.cats

https://doi.org/10.58998/jnr3209
Beginning in the 1960s, human activities have led to an increase in atmospheric CO2 concentration 100 times fasterthan with previous natural increases. Approximately 30% of anthropogenic CO2 is absorbed by the oceans, leading tochanges in ocean chemistry termed ocean acidification (OA). Several studies have focused on the effects of increasing
CO2 on calcifying organisms, including coccolithophores. Responses of coccolithophores to OA appear to be species
specific, but only a few species (from approximately 250 living species) have been studied, which warrants further studies. Helicosphaera carteri is a common coccolithophore species. It is considered a major contributor to carbon uptake
and CaCO3 storage in deep-sea sediments due to its large size and higher rates of organic carbon fixation and calcite
production compared to smaller species. Despite its important role, only a few studies have been conducted on living H.
carteri under experimental conditions, and none have considered the effects of rising CO2.
In this work, we study for the first time the response of H. carteri (Strain RCC1323, Roscoff Culture Collection) tovarying CO2 (295, 444, 600 ppm) by analyzing its variations in morphology, growth rate, and particulate organic carbon(POC) and inorganic carbon (PIC) production. Our results show that H. carteri is not very sensitive to pH/CO2 variations. From a morphological point of view, there is only a 10% increase in slightly malformed coccoliths and <1% of
collapsed coccospheres when CO2 amounts are increased from 295 to 600 ppm.
A preliminary comparison of malformed coccoliths of H. carteri with another heavily calcified species, Calcidiscus
leptoporus, (grown under experimentally controlled conditions at CO2 levels close to 600 ppm), shows that the percentage of malformed coccoliths in C. leptoporus is higher than that in our H. carteri experiments, and with a greater amountof malformation (Langer et al., 2006; Diner et al., 2015). This indicates that H. carteri has a greater resilience than C.
leptoporus to CO2 variation. However, there was a decrease in PIC production (-26%) and the PIC:POC ratio (-29.6%)
with increasing CO2 levels, showing that H. carteri is sensitive to ocean acidification.
Moreover, a decrease in H. carteri growth rate (µ) occurred at the lowest (295 ppm; 0.36 µ/day, decrease of 18%)and highest (600 ppm; 0.40 µ/day, decrease of 9%) CO2 concentrations compared to the control culture (444 ppm; 0.44µ/day), indicating a possible influence of CO2 limitation (295 ppm) and H+ inhibition (600 ppm), respectively. However,this decrease is not related to a decrease in POC production, as previously was observed by other authors in association to these two limiting factors (e.g., Bach et al., 2011). Indeed, POC production does not change significantly from
295 to 444 ppm, and contrary to the growth rate, it increases from the intermediate CO2 level to the highest. Our results
highlight the complexity of coccolithophore responses to increased CO2 and underscore the need to collect extensive
data from different species.

26

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Acknowledgements:

This research was funded by the Okada-McIntyre Graduate Research Fellowship 2023, awarded to Stefania Bianco.
References:Bach, L.T., Riebesell, U. & Schulz, K.G. 2011. Distinguishing between the effects of ocean acidification and ocean carbonation in the coccolithophore
Emiliania huxleyi. Limnology and Oceanography, 56: 2040–2050. https://doi.org/10.4391/lo.2011.56.6.2040
Diner, R.E., Benner, I., Passow, U., Komada, T., Carpenter, E.J. & Stillman, J.H. 2015. Negative effects of ocean acidification on calcification vary
within the coccolithophore genus Calcidiscus. Marine Biology, 162: 1287–1305. https://doi.org/10.1007/s00227-015-2669-x
Langer, G., Geisen, M., Baumann, K.H., Kläs, J., Riebesell, U., Thoms, S. & Young, J.R. 2006. Species-specific responses of calcifying algae tochanging seawater carbonate chemistry. Geochemistry, Geophysics, Geosystems, 7(9): Q09006. https://doi.org/10.1029/2005GC001227

INA1927

Last glacial to Holocene sedimentation patterns and coccolithophore dynamics in the northwestern Bay of Bengal in
response to South Asian monsoon strengthening
Clara T. Bolton

Aix-Marseille University, CNRS, IRD, CEREGE, 13090 Aix-en-Provence, France; bolton@cerege.fr

Phyo Wai Thant

Aix-Marseille University, CNRS, IRD, INRAE, CEREGE, Aix-en-Provence, France; phyowaithant60@gmail.com

Stephen C. Philips

U.S. Geological Survey, Woods Hole Science Center, Woods Hole, MA, 02543, USA; scphillips@usgs.gov

Luc Beaufort

Aix-Marseille University, CNRS, IRD, INRAE, CEREGE, 13090 Aix-en-Provence, France; beaufort@cerege.fr

Kaustubh Thirumalai

University of Arizona, Department of Geosciences, 1040 E, 4th Street Tucson, AZ 85721, USA; kaustubh@arizona.edu

https://doi.org/10.58998/jnr3210
In the modern northern Indian Ocean, biological productivity is intimately linked to near-surface, ocean–atmosphere
dynamics forced by the South Asian monsoon (SAM). The interplay between monsoon winds and precipitation, ocean
carbon cycle feedbacks, and climate forcing mechanisms in the oceanographically heterogeneous Bay of Bengal remains poorly understood. In the southern Bay of Bengal, seasonally reversing winds are the dominant control on mixingthat brings nutrients into the mixed layer, thus stimulating productivity. However, in the northern Bay of Bengal, monsoon precipitation and runoff that peaks during the late summer–early autumn strongly influences upper water column
structure, inducing strong stratification that may inhibit phytoplankton productivity.
Here, we present new high-resolution records of past biogenic sediment mass accumulation rates, coccolith assemblages, coccolith CaCO3 export, and coccolith morphology that span the period from the Last Glacial Maximum to the
Holocene (the last ~26 kyr). We examined samples from International Ocean Discovery Program (IODP) Site U1446
in the Mahanadi Basin (NW Bay of Bengal), a region strongly impacted by monsoon runoff. During the Last Glacial
Maximum and the following deglaciation, we found that an increase in the relative abundance of upper photic zone coccolithophore species coincided with reduced stratification and runoff, which potentially increased nutrients as a result ofa weaker SAM. In contrast, the lower photic zone species Florisphaera profunda displayed a higher relative abundance
during the Holocene (up to 80%) due to strong salinity stratification that can be linked with increased precipitation andrunoff that was the result of a stronger Indian Summer Monsoon (ISM). Throughout the study interval, and in particular under conditions of maximum stratification in the Holocene, F. profunda coccoliths dominated coccolith absoluteabundances and mass accumulation rates, highlighting the importance of deep photic zone species in coccolith CaCO3
and potentially organic C export into certain environments. Within the reticulofenestrid coccoliths, smaller morphotypes
dominated during the strongly stratified Holocene, whereas larger reticulofenestrid coccoliths were more abundant during the glacial and deglaciation. Within the <3 µm reticulofenestrid coccolith group, mean coccolith mass decreased
from the glacial to the Holocene, suggesting that more stratified and/or fresher conditions favored smaller and more
lightly calcified morphotypes.

28

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The uncultivated side of coccolithophores: Digging into theorganic matter
Chiara Bonatelli

University School for advanced Studies IUSS Pavia, 27100 Pavia, Italy; University of Pavia, Department of Earth and Environmental Sciences,
27100 Pavia, Italy; chiara.bonatelli@iusspavia.it

Manuela Bordiga

National Institute of Oceanography and Applied Geophysics-OGS, 34151 Trieste, Italy; mbordiga@ogs.it

Giovanni Birarda, Lisa Vaccari

Elettra Sincrotrone Trieste, 34049 Trieste-Basovizza, Italy; giovanni.birarda@elettra.eu; lisa.vaccari@elettra.eu

Daniele Dondi, Dhanalakshmi Vadivel

University of Pavia, Department of Chemistry, Section of General Chemistry, 27100 Pavia, Italy;
daniele.dondi@unipv.it; dhanalakshmi.vadivel@unipv.it

Andrea Stefano Di Giulio, Claudia Lupi

University of Pavia, Department of Earth and Environmental Sciences, 27100 Pavia, Italy; andrea.digiulio@unipv.it; claudia.lupi@unipv.it

https://doi.org/10.58998/jnr3211
The calcium carbonate production from coccolithophores has been widely studied because of its important contribution
to global biogeochemical cycles and long-term carbon fluxes. On the other hand, the organic fraction of coccolithophores is still poorly studied, despite its importance in carbon transfer among different oceanic reservoirs. To date, only
the species Emiliania huxleyi has been studied in detail for its organic composition (Aveiro et al., 2020): >50% CaCO3,
20% lipids, 15% proteins, and 4% carbohydrates. Specific studies on other species of coccolithophores are necessary todifferentiate their organic fraction production.
To increase the knowledge of the organic compounds involved in coccolithophore physiology, Helicosphaera carteri was chosen as the target species. The analysis was carried out at a lower resolution with easily accessible instruments(e.g., benchtop Fourier Transform Infrared (FTIR) Spectroscope). This species’ relatively large cell size (15 μm), as
compared to E. huxleyi, makes possible a more detailed analysis at the single cell level, exploiting the higher brightness of the synchrotron source. Here, the IR spectra obtained from both entire coccospheres and decalcified cells arecompared to data (10 μm spatial resolution) that were collected at the Synchrotron Infrared Source for Spectroscopy andImaging (SISSI-Bio) beamline at Elettra Sincrotrone Trieste (Italy), during the beamtime #20235227, on single naked
cells and coccoliths detached through both mechanical and chemical treatments.
The data acquired on entire coccospheres (3 replicates) with laboratory FTIR were recorded using only 5 mg offreeze-dried residue of H. carteri. At first, we detected weak peaks of lipids, proteins, carbohydrates, and nucleic acids
because the presence of CaCO3, which returned a strong signal at ~1410/cm, masked the peaks of the organic compounds. After a HCl 1M treatment, the spectra at FTIR on decalcified cells documented the presence of stronger peaksof the above-mentioned organic compounds and returned a clearer overview of the organic composition. The analysis at
SISSI-Bio was performed on decalcified single cells stored in acid Lugol’s solution and single coccoliths of H. carteri.
We analyzed 100 naked cells and coccoliths that were both mechanically and chemically separated for a total of 300
different spectra. The data showed a clearer signal of the individual organic macromolecules such as proteins, polysaccharides, and lipids compared to the previous FTIR data. Moreover, at the SISSI-Bio, the analysis of organic matter onindividual coccoliths obtained by mechanical separation documented the occurrence of weak signals of polysaccharides
and proteins, in contrast to those chemically treated with Triton-X, bleach, and hydrogen peroxide, where only the peaksof CaCO3 are evident. Multivariate analysis will be used to highlight more subtle differences between the treatments andprovide more detail on protein conformation and lipid order.
In conclusion, our work draws attention once again to the importance of sample preparation and documents the pos-

INA1929

sibility of performing FTIR analyses in the laboratory with good results even when having microquantities of residue
available. Moreover, our data underline the importance of using innovative, high-resolution techniques for a bettercharacterization of the organic matter produced by coccolithophores during their life cycle. This is critical for a better
understanding of their physiology and thus the role that different organic compounds might play in coccolithogenesis
and biocalcification.
Acknowledgements:

We thank Elettra Sincrotrone Trieste for beamtime allocation #20235227 at SISSI-Bio beamline to Chiara Bonatelli.
References:
Aveiro, S.S., Melo, T., Figueiredo, A., Domingues, P., Pereira, H., Maia, I.B., Silva, J., Domingues, M.R., Nunes, C. & Moreira, A.S.P. 2020. The
Polar Lipidome of Cultured Emiliania huxleyi: A Source of Bioactive Lipids with Relevance for Biotechnological Applications. Biomolecules,
10(10): 1434. https://doi.org/10.3390/biom10101434

30

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Aptian–Albian calcareous nannofossils from the South
Atlantic
Ocean:
Implications
forpaleoclimate
andpaleogeography
Cinzia Bottini

Università degli Studi di Milano, Dipartimento di Scienze della Terra “Ardito Desio,” 20133 Milano, Italy; cinzia.bottini@unimi.it

Chiara Bettoni, Elisabetta Erba

Università degli Studi di Milano, Dipartimento di Scienze della Terra “Ardito Desio,” 20133 Milano, Italy; chiara.bettoni@unimi.it;
elisabetta.erba@unimi.it

Jens O. Herrle

Goethe-University Frankfurt, Institute of Geosciences, 60438 Frankfurt am Main, Germany; jens.herrle@em.uni-frankfurt.dehttps://doi.org/10.58998/jnr3212
Calcareous nannofossil assemblages indicate marked changes in surface-water temperature and fertility across the Aptian–Albian transition. However, most records are from the northern hemisphere, and less is known about the responseof calcareous nannoplankton in the southern hemisphere. Here, we focus on two locations in the South Atlantic Ocean,namely Deep Sea Drilling Project (DSDP) Site 364 (Kwanza Basin) and DSDP Site 511 (Falkland Plateau), to analyze
the paleoceanographic and paleoclimatic changes in the Southern Ocean during the Aptian–Albian transition interval.
Calcareous nannofossils were investigated to refine the biostratigraphy, obtain relative abundances, and document
size variations of Watznaueria barnesiae and Biscutum constans. A comparison with the Tethyan record (Cismon andPiobbico cores) allowed for the differentiation between local and global factors such as paleotemperature and paleofertility. Notably, some similarities in the temperature trends were observed, but there was evidence of cooler conditions at
DSDP Site 511, possibly indicative of latitudinal gradients that were established during the Aptian–Albian transition. A
moderate change occurred in the calcareous nannofossil assemblage composition with the appearance of abundant coldwater species such as Repagulum parvidentatum and more abundant surface-water fertility taxa such as B. constans andZeugrhabdotus erectus in the early late Albian at DSDP Site 511. Paleofertility exhibited more localized changes except
during the Aptian/Albian boundary interval, which is marked by a temperature rise and increased fertility, aligning withobservations in the western Tethyan Ocean. This serves as evidence of the global nature of the warming phase associatedwith this interval, likely triggered by volcanism from the Kerguelen Plateau Large Igneous Province.
Morphometric analyses of W. barnesiae and B. constans revealed similar responses and trends to those identified in
the Tethys but with larger average coccolith length and width values in the South Atlantic. Watznaueria barnesiae isconfirmed to display a much less pronounced size change compared to B. constans, which is now confirmed to be moresensitive to paleoenvironmental changes.

INA19What drove nannoplankton evolution
dynamics through the Paleogene?

31

and

community

Paul Bown

University College London, Department of Earth Sciences, London, UK; p.bown@ucl.ac.uk

Claire Routledge

Christian-Albrechts-University of Kiel, Institute of Geosciences, Kiel, Germany; claire.routledge@ifg.uni-kiel.de

Samantha Gibbs

University College London, Department of Earth Sciences, London, UK; p.bown@ucl.ac.uk

Cherry Newsam

Network Stratigraphic Consulting Limited, Potters Bar, Hertfordshire, UK; cherry.newsam.11@alumni.ucl.ac.uk

Sarah Alvarez

University of Gibraltar, Europa Point Campus, Gibraltar; sarah.alvarez@unigib.edu.gi

Hojung Kim

University College London, Department of Earth Sciences, London, UK; hojung.kim.09@alumni.ucl.ac.uk

Odysseas A. Archontikis

University of Oxford, Department of Earth Sciences, Oxford OX1 3AN, UK; University College London, Department of Earth Sciences, London,
WC1E 6BT, UK; odysseas.archontikis@univ.ox.ac.uk

https://doi.org/10.58998/jnr3213
Cenozoic calcareous nannoplankton records reveal profound changes in diversity, morphology, and community composition, but what were the primary controls on these parameters through time since the dramatic taxonomic reset atthe Cretaceous/Paleogene mass extinction 66 million years ago? Here we will examine the evolution of nannoplankton
through the first 44 million years of the Cenozoic (Danian to Aquitanian), using a range of approaches that include biometry (liths and coccospheres) and long time series community analyses. Our dataset spans the time interval that saw
recovery of nannoplankton communities following the devastating mass extinction and their co-evolution alongsideprofound extrinsic changes as the Earth system shifted from warm early Paleogene greenhouse climates to cooler temperatures of the Oligocene coolhouse (~33 Ma). We will show that in the first two million years after the mass extinction
there was exceptional community variability, predominantly in small lith and cell sizes, and unusual trophic strategies,
most notably mixotrophy in the most widespread and dominant taxa. A rapid regime change occurred after this, associated with rising species richness, rapidly increasing cell sizes, diversifying trophic strategies, and the emergence of astable background community state. These biotic shifts were reflected in broader biogeochemical changes, such as recovery of biological pump function and increasing food web complexity. Our subsequent time-series community records
demonstrate an enduring stability and resilience despite long-term changes in climate, but this stability was punctuatedby ephemeral excursions of above background levels of disruption, associated with both warming (e.g., the early Eocene
hyperthermals) and cooling events (e.g., the Eocene–Oligocene transition and several Oligocene glaciations). Thesetransient community perturbations show threshold behavior that can be linked to magnitudes of temperature change,
and they scale with environmental parameters, in particular rising and falling temperature. These relationships hold forplankton communities through the entire Paleocene to Early Miocene record with temperature being the primary driver,modulating communities in a similar way regardless of the greenhouse or icehouse background climate state.

32

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Paleoclimatic reconstruction of the past 28 kyr BP based on
calcareous nannofossil assemblages in the Ligurian Sea
Laura Bronzo

University of Florence, Earth Sciences Department, Florence, Italy; laura.bronzo@unifi.it

Antonio Cascella

University of Florence, Earth Sciences Department, Italy and National Institute of Geophysics and Volcanology (INGV), Florence, Italy; antonio.
cascella@ingv.it

Pierluigi Martinelli, Rocco Gennari

University of Turin, Earth Sciences Department, Turin, Italy; pierluigi.martinelli@unito.it; rocco.gennari@unito.it

José Abel Flores

University of Salamanca, Geology Department, Salamanca, Spain; flores@usal.es

Sergio Bonomo, Giulia Margaritelli

Italian National Research Council, Institute of Environmental Geology and Geoengineering (CNR-IGAG), Rome, Italy; Italian National ResearchCouncil, Research Institute for the Geo-Hydrological Protection (CNR-IRPI), Perugia, Italy;
sergio.bonomo@igag.cnr.it; giulia.margaritelli@irpi.cnr.it

Caterina Morigi

University of Pisa, Earth Sciences Department, Pisa, Italy; caterina.morigi@unipi.it

Isabel Cacho, Jaime Frigola

Universitat de Barcelona, GRC Geociències Marines, Departament de Dinàmica de la Terra i de l’Oceà, Facultat de Ciències de la Terra, Barcelona,
Spain; icacho@ub.edu; jfrigola@ub.edu

Mar Selvaggi, Letizia Di Bella, Fabrizio Lirer

Sapienza University of Rome, Earth Sciences Department, Rome, Italy; selvaggi.mar@gmail.com; letizia.dibella@uniroma1.it;fabrizio.lirer@uniroma1.it

https://doi.org/10.58998/jnr3214
The climatic events that marked the last 28 kyr (e.g., Heinrich Stadials [HS], Last Glacial Maximum, Younger Dryas,
and Bølling-Allerød) have been identified and described in the Mediterranean Sea. Nevertheless, some of its areas, suchas the northern Tyrrhenian Sea, are still poorly investigated and lack data and paleorecords. The core NDT_22 was collected from 436 m of water in the Ligurian Sea and consists of 320 cm of greenish to greyish fine sentiments. The age
model is based on 14 radiocarbon (14C) accelerator mass spectrometry (AMS) measurements on the planktonic foraminifera Globigerina bulloides and dates the bottom of the core at 27.4 kyr BP. Calcareous nannofossil assemblages werestudied at a resolution of 170 yr/sample. The distribution of calcareous nannofossils was investigated by considering thecalcareous nannofossil accumulation rate (NAR) and their relative abundance (%).
In general, abundance of the warm-water group (Calciosolenia spp., Discosphaera tubifera, Oolithothus fragilis,
Rhabdosphaera spp., Umbellosphaera spp., and Umbilicosphaera spp.) increased from the onset of the Bølling-Allerødinterval (~14.4–12.8 kyr BP), peaking during the early Holocene (between 10.3 and 9 kyr BP). Conversely, the coldwater group (Coccolithus pelagicus, Emiliania huxleyi >4 µm, and Gephyrocapsa muellerae) showed higher values
throughout the Late Pleistocene, decreasing after the Younger Dryas (~12.8–11.7 kyr BP). Florisphaera profunda increased from the Bølling-Allerød and reached significant values during the Holocene, marking the development of
seasonal stratification. Higher values of reworked coccoliths and the presence of Helicosphaera carteri highlighted
enhanced runoff during HS2 (26.1–23.7 kyr BP) and HS1 (17.2–14.4 kyr BP).
Acknowledgements:

This research was financially supported by the ERC-Consolidator 539 TIMED project (REP-683237), Project of Strategic Interest NextData PNR 2011–2013, MUR (University of Florence) PhD and Erasmus+ scholarships.

INA1933

Calcareous nannofossil assemblages as evidence of shifts in
the Arctic/Polar Fronts during the past 24 kyr BP along theWest Spitsbergen margin
Laura Bronzo

University of Florence, Earth Sciences Department, Florence, Italy; laura.bronzo@unifi.it

Fernando Sergio Gois Smith

University of Florence, Earth Sciences Department, Florence, Italy; fernandosergio.goissmith@unifi.it

Caterina Morigi

University of Pisa, Earth Sciences Department, Pisa, Italy; caterina.morigi@unipi.it

Antonio Cascella, Chiara Caricchi, Leonardo Sagnotti
National Institute of Geophysics and Volcanology (INGV) Pisa, Rome, Italy;antonio.cascella@ingv.it; chiara.caricchi@ingv.it; leonardo.sagnotti@ingv.it

Renata Giulia Lucchi

National Institute of Oceanography and Experimental Geophysics (INOGS), Trieste, Italy; rglucchi@inogs.it

https://doi.org/10.58998/jnr3215
The study of well-preserved Arctic marine sedimentary deposits is pivotal to understanding the impact of climate changes on ecological and sedimentary scales. From the Last Glacial Maximum to the onset of the Holocene, the climate
underwent abrupt changes that caused Heinrich events and episodes of rapid sea level rise known as meltwater pulses(MWPs). To unravel the effects of these events on thermohaline ocean circulation in the Arctic region, a multiproxybased approach is essential. Here, we investigated calcareous nannofossil assemblages, and coupled the results with
X-ray fluorescence (XRF) and Greenland ice core δ18O data.
The piston core IRIDYA-02PC was collected on the Bellsund Drift crest along the West Spitsbergen margin. The
core was sampled at a water depth of 1724 m, and it recovered 4.87 m of sediments that are distinguished by bioturbatedand laminated sediments with sparse to massive ice-rafted debris and oxidized layers. The age model is based on three
radiocarbon ages and on the reconstruction of a high-resolution relative paleointensity and paleosecular variation of
the geomagnetic field record for the last 24 kyr BP. The calcareous nannofossil content of the IRIDYA-02PC core wasinvestigated with a 240 yr/sample resolution.
Oscillations in total nannofossil abundance and reworked coccoliths (both expressed as number of nannofossils pergram of sediment) were compared with Ca/Ti and Zr/Rb, indicating oscillations in marine biogenic carbonate content
and sediment grain size, respectively. The logarithmic ratio between the warm-water group (Emiliania huxleyi, Gephyrocapsa oceanica, small Gephyrocapsa, and Calcidiscus leptoporus) and the cold-water group (E. huxleyi >4 μm,
Gephyrocapsa muellerae, and Coccolithus pelagicus pelagicus) (log[WWG/CWG]) was calculated to evidence shifts in
the Polar Front along the West Spitsbergen margin.
During the Late Pleistocene, a decrease in abundance of both total and reworked coccoliths highlights Heinrich-like(H2, H1), Younger Dryas, and MWP-1A abrupt events that correspond to peaks in Zr/Rb values. In contrast, their slightincrease in abundance is evidence of the Last Glacial Maximum and the Allerød episode with the log(WWG/CWG),
suggesting the formation of a seasonal sea-ice cover over the study site. From 11.2 kyr BP, a sharp increase in total nannofossil abundance indicates the development of Holocene warmer conditions as evidenced by the log(WWG/CWG),
which points to a prominent retreat of the Polar Front.
Acknowledgements:

This study is financially supported by IRIDYA (PRA2021-0012) project and MUR (University of Florence) PhD.

34

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Not a source of atmospheric CO2…
Mário Cachão

University of Lisbon, Department of Geology, Faculty of Sciences & Instituto Dom Luiz, Campo Grande 1749-016 Lisboa, Portugal;
mcachao@fc.ul.pt

Mª Rosário Carvalho

University of Lisbon, Department of Geology, Faculty of Sciences & Instituto Dom Luiz, Campo Grande 1749-016 Lisboa, Portugal;
mdrcarvalho@fc.ul.pt

https://doi.org/10.58998/jnr3216
Many authors refer to the precipitation of calcium carbonate from sea water expressed by equation [1], either by purely
chemical mechanisms (e.g., an increase in sea surface temperature [SST]) or mediated by organisms such as coccolithophores (biomineralization) as a source of CO2(g) degassing back to the atmosphere (e.g., Hutchins, 2011).
Ca2+ + 2 HCO3-<=> CaCO3(s) + H2O + CO2(g)[1]However, there are four reasons why the precipitation of calcium carbonate from seawater does not contribute to atmospheric CO2(g):Reason #1 – The overall cycle. Equation [1] does not take into consideration the entire geochemical process, startingwith the weathering (hydrolysis in acidic conditions) of crustal rocks rich in calcium silicates, such as a metamorphic
rock rich in the inosilicate Wollastonite (CaSiO3) or a magmatic mafic rock with plagioclase anorthite (CaAl2Si2O8). In
this last case, the hydrolysis of the feldspar occurs according to equation [2].
CaAl2Si2O8 + 8 H+ <=> Ca2+ + 2 A13+ + 2 SiO2 (aq.) + 4 H2O[2]

The main supplier of H+ is the CO2(g), according to equations [3] and [4]. To maintain the bivalent calcium insolution, two molecules of CO2(g) are needed to produce the two negative bicarbonate ions on the left side of equation [1]promoting acidic conditions, i.e., with two protons (H+) in excess.
			2 CO2(g) + 2 H2O <=> 2 H2CO3
2 H2CO3 <=> 2 HCO3- + 2 H+

[3]
[4]

Thus, the overall balance of this mechanism ([3] + [4] + [2] + [1]) indicates that this mechanism is a sink and not asource of CO2(g). On the other hand, if instead of siliceous magmatic or metamorphic rocks, one considers the weathering (karstification) of sedimentary Ca-rich rocks such as limestone or marble, the overall process is neutral (neither asink nor a source) for CO2(g) because in this case the solubilization of the calcium only requires one molecule of carbon
dioxide (equation [1] from right to left), which is “released” by the precipitation of calcium carbonate (equation [1] fromleft to right). Many may argue that these geological processes occur at much longer time scales, but we will present a
study on weathering of monuments in Lisbon that demonstrates that this is not the case.
Reason #2 – There is no addition of [CO2]. Equation [1], as in any other chemical balance equation, indicates thatboth sides are equivalent in terms of mass and so, the molecule CO2 that appears on the right side is already in the medium, i.e., there is no addition of dissolved inorganic carbon (DIC) to the system due to precipitation of CaCO3 itself.
Reason #3 – Part is used to produce sugars. Significant amounts of CO2 are absorbed by coccolithophores and otherphotosynthetic organisms to produce carbohydrates and other forms of organic carbon. While some of this organiccarbon may be remineralized in the water column or due to resuspension (Smeaton & Austin, 2022), for example, anestimated 266 Gt of organic carbon is incorporated only within the top 1 meter of sediment of the continental shelves

INA1935

worldwide (Atwood et al., 2020).
Reason #4 – The pH factor. When the alkaline ion Ca2+ is incorporated into the seawater solution from river discharges, it increases the ocean’s alkalinity, which in turn promotes the dissolved inorganic carbon (DIC) chemical species on
the right side of equation [4], releasing H+ and thus diminishing the ocean’s pH.
HCO3- <=> CO32- + H+

[5]

As with most calcifying organisms, coccolithophores preferentially uptake DIC in the form of HCO3- mainly because it is the dominant chemical species in current pH oceanic conditions (Glotter et al., 2014). In coccolithophores,
the buildup of protons from equation [5] led to the appearance of mechanisms designed to eliminate H+ in excess while
promoting the uptake of the bivalent ion calcium via solute carrier 4 (SLC4) family, a Ca2+/H+ exchanger of the CAX
family of exchangers and a vacuolar H+- ATPase (Mackinder et al., 2011; Brownlee et al., 2021).
Thus, for sea water with pH around 8, equation [1] should be rewritten as:
Ca2+ + 2 HCO3-<-> CaCO3 + H+ + HCO3-

(aq.)

[6]

<-> CaCO3 + 2 H+ + CO32-

(aq.)

[7]

As well as, in lower concentrations:
Ca2+ + 2 HCO3-

We will present results from modeling the forced precipitation of CaCO3 due to the (bio)mineralization of calcite ascoccoliths from seawater at a pH of around 8, showing that the remaining DIC always tends to stay in solution according
to equations [6] and [7] (Parkhurst & Appelo, 1999). Therefore, the precipitation of CaCO3 does not serve as a source of
CO2 as a gas for the sea water and much less for the atmosphere.
References:
Atwood, T.B., Witt, A., Mayorga, J., Hammill, E., Sala, E. & Dale, A.W. 2020. Global patterns in marine sediment carbon stocks. Frontiers in Marine
Science, 7: 1–9. https://doi.org/10.3389/fmars.2020.00165
Brownlee, C., Langer, G. & Wheeler, G.L. 2021. Coccolithophore calcification: changing paradigms in changing oceans. Acta Biomaterialia, 120:
4–11. https://doi.org/10.1016/j.actbio.2020.07.050
Glotter, M.J., Pierrehumbert, R.T., Elliot, J.W., Matteson, N.J. & Moyer, E.J. 2014. A simple carbon cycle representation for economic and policy
analyses. Climate Change, 126: 319–335. https://doi.org/10.1007/s10584-014-1224-y
Hutchins, D.A. 2011. Forecasting the rain ratio. Nature, 476: 41–42. https://doi.org/10.1038/476041a
Mackinder, L., Wheeler, G., Schroeder, D., von Dassow, P., Riebesell, U. & Brownlee, C. 2011. Expression of biomineralization-related ion transport
genes in Emiliania huxleyi. Environmental Biology, 13(12): 3250–3265. https://doi.org/10.1111/j.1462-2920.2011.02561.x
Parkhurst, D.L. & Appelo, C.A.J. 1999. PHREEQC (Version 2): A computer program for speciation, batch-reaction, one-dimensional transport, andinverse geochemical calculations. U.S. Geological Survey Water-Resources Investigations Report 99-4259: 312pp.
Smeaton, C. & Austin, W.E.N. 2022. Quality Not Quantity: Prioritizing the Management of Sedimentary Organic Matter Across Continental Shelf
Seas. Geophysical Research Letters, 49(5): e2021GL097481. https://doi.org/10.1029/2021GL097481

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Preliminary results of calcareous nannofossil analyses of
Neogene and Quaternary units in northwestern Pangasinan,
Philippines
Joeven Austine Calvelo

University of the Philippines, Diliman, National Institute of Geological Sciences, Nannoworks Laboratory, Quezon City 1101 Philippines;
jscalvelo1@up.edu.phAlyssa M. Peleo-Alampay

University of the Philippines, Diliman, National Institute of Geological Sciences, Nannoworks Laboratory, Quezon City 1101 Philippines;
ampeleoalampay@up.edu.phAllan Gil S. Fernando

University of the Philippines, Diliman, National Institute of Geological Sciences, Nannoworks Laboratory, Quezon City 1101 Philippines;
asfernando@up.edu.phAntero II Borja

University of the Philippines, Diliman, National Institute of Geological Sciences, Nannoworks Laboratory, Quezon City 1101 Philippines;
anteroiiborja@gmail.com

https://doi.org/10.58998/jnr3217
This study presents the preliminary results of a calcareous nannofossil analysis of samples collected from exposed
Neogene and possible Quaternary marine sequences in northwestern Pangasinan, Philippines. The study was conducted
to refine the ages and distribution of previously mapped lithostratigraphic units, as well as refine understanding of thegeology and stratigraphy of the region.
Samples that were collected from a mass transport deposit were assigned to nannofossil Zone NN10 (early Late
Miocene) or older based on the occurrence of Cyclicargolithus floridanus, Reticulofenestra pseudoumbilicus, Catinaster
calyculus, and C. coalitus. An intercalated calcareous siltstone and limestone unit, assigned to Zones NN8–10 (early
Late Miocene), overlies these deposits, and this unit was tentatively assigned to the Cabaluan Formation, which waspreviously dated Middle–Late Miocene on the basis of planktonic foraminiferal assemblages. Limestones, fine- to veryfine-grained sandstones, and finer grained clastic rocks, which are widely distributed in the study area, were dated early
Late Miocene to late Early Pliocene (nannofossil Zones NN10–16) based on the occurrences of Amaurolithus delicatus,
Ceratolithus cristatus, Discoaster pentaradiatus, D. quinqueramus, D. surculus, D. triradiatus, Helicosphaera orientalis, H. pacifica, H. stalis, Reticulofenestra pseudoumbilicus, R. haqii, R. minuta, R. rotaria, Pseudoemiliania lacunosa,
and small gephyrocapsids. These units are tentatively assigned to the Santa Cruz Formation, which was previously dated
late Late Miocene.
Ongoing geological fieldwork and mapping, including petrographic, structural, and microfacies analyses, will determine whether these Pliocene units belong to the Santa Cruz Formation, Bolinao Limestone (Pliocene–Pleistocene), or apreviously unmapped lithostratigraphic unit.

INA1937

Gradual phyletic evolution of Reticulofenestra oamaruensis
from Reticulofenestra clatrata: A rare example of calcareous
nannoplankton microevolution preserved in the sedimentary
record at IODP Site U1553 (southern Pacific Ocean)
Valentina Catelli

Università degli Studi di Parma, Dipartimento di Scienze Chimiche, della Vita e della Sostenibilità Ambientale - SCVSA, I-43124 Parma, Italy;
valentina.catelli@unipr.it

Davide Persico, Davide Righi

Università degli Studi di Parma, Dipartimento di Scienze Chimiche, della Vita e della Sostenibilità Ambientale - SCVSA, I-43124 Parma, Italy;
davide.persico@unipr.it; davide.righi@unipr.it

Isabella Raffi

Università degli Studi “G. d’Annunzio” di Chieti-Pescara, International Research School of Planetary Sciences - IRSPS, I-65127 Pescara, Italy;
isabella.raffi@unich.it

Chiara Fioroni

Università degli Studi di Modena e Reggio Emilia, Dipartimento di Scienze Chimiche e Geologiche, I-41125, Modena, Italy;
chiara.fioroni@unimore.it

Giuliana Villa

Università degli Studi di Parma, Dipartimento di Scienze Chimiche, della Vita e della Sostenibilità Ambientale - SCVSA, I-43124 Parma, Italy;
giuliana.villa@unipr.it

https://doi.org/10.58998/jnr3218
Persico et al. (2014) first proposed a possible gradual phyletic evolution of Reticulofenestra oamaruensis from R. clatrata during the study of Ocean Drilling Program (ODP) Sites 738, 748, 744 (Kerguelen Plateau), and 689 (Maud Rise).
International Ocean Discovery Program (IODP) Expedition 378 Site U1553, drilled in the Southern Ocean (Campbell
Plateau), recovered a continuously cored, multiple-hole (U1553A–U1553E) Paleogene sedimentary section (Röhl etal., 2022). The good preservation of calcareous nannofossils in these cores made possible a study of the origin of R.
oamaruensis and its intraspecific variability, as well as its biostratigraphic distribution in the middle–late Eocene. The
original description of this transition only considered samples with sizes of 13.8–17 µm, but our biometric analyses andmorphological investigations suggest including transitional morphotypes of R. oamaruensis (10–14 µm). Morphometricquantitative studies allowed us to recognize an intraspecific evolutionary trend that is characterized by a gradual increase in size of small specimens of R. clatrata (8–10 µm), which are present from the base of the stratigraphic sequence(263.81 m core composite depth below seafloor [CCSF]) (Raffi et al., submitted), to large specimens of R. oamaruensis(>14 µm). Intermediate specimens were placed into two size categories (10–12 µm and 12–14 µm). All “morphotypes”,
including species with sizes defined in the original descriptions, disappear simultaneously during the Eocene–Oligocenetransition (Raffi et al., submitted). Intermediate morphotypes appear as distinct and stratigraphically identifiable events,suggesting a potential “lineage zone” that is useful in Southern Ocean biostratigraphy. The morphological homology,
the continuity in the stratigraphic distribution, the same geographical distribution area, and the presence of a gradually
increasing size trend from R. clatrata to R. oamaruensis represent a possible phyletic lineage that is endemic to highsouthern latitudes where R. clatrata represents the archetype.
References:
Persico, D., Villa, G. & Ladner, B. 2014. Size variations of Reticulofenestra oamaruensis (Deflandre in Deflandre & Fert, 1954) Stradner in Haq,
1968, emended. Revue de Micropaléontologie, 57(1): 15–21. https://doi.org/10.1016/j.revmic.2014.02.001
Raffi, I., Catelli, V., Fioroni C., Righi, D., Villa, G. & Persico, D. submitted. Calcareous nannofossils from the Paleogene Southern Ocean (IODP Site
U1553, Campbell Plateau). Newsletters on Stratigraphy.

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Röhl, U., Thomas, D.J., Childress, L.B., Anagnostou, E., Ausín, B., Borba Dias, B., Boscolo-Galazzo, F., Brzelinski, S., Dunlea, A.G., George, S.C.,
Haynes, L.L., Hendy, I.L., Jones, H.L., Khanolkar, S.S., Kitch, G.D., Lee, H., Raffi, I., Reis, A.J., Sheward, R.M., Sibert, E., Tanaka, E., Wilkens,
R., Yasukawa, K., Yuan, W., Zhang, Q., Zhang, Y., Drury, A.J., Crouch, E.M. & Hollis, C.J. 2022. Site U1553. Proceedings of the International
Ocean Discovery Program, 378. https://doi.org/10.14379/iodp.proc.378.103.2022

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New biostratigraphic data for the Lower–Middle Jurassic Los
Molles Formation in the Picún Leufú area, Argentina
Micaela Chaumeil Rodríguez

Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Instituto de Investigación en Paleobiología y Geología (IIPG, CONICETUNRN, 8332 General Roca, Río Negro, Argentina; micachaumeil@gmail.com

Juan Pablo Pérez Panera

Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). División Geología, Museo de La Plata, Facultad de Ciencias Naturales y
Museo, Universidad Nacional de La Plata, 1900 La Plata, Buenos Aires, Argentina; perezpanera@gmail.com

Guillaume Suan

Université Claude Bernard Lyon 1, ENS de Lyon, CNRS, LGL-TPE, F-69622, Villeurbanne, France; guillaume.suan@univ-lyon1.fr

Jorge Enrique Spangenberg

University of Lausanne, Institute of Earth Surface Dynamics, Géopolis, CH-1015 Lausanne, Switzerland; jorge.spangenberg@unil.ch

Alberto Carlos Garrido

Museo Provincial de Ciencias Naturales Prof. Dr. Juan Olsacher, Zapala, Neuquén, Argentina; albertocarlosgarrido@gmail.com

Emanuela Mattioli

Université Claude Bernard Lyon 1, ENS de Lyon, CNRS, LGL-TPE, F-69622, Villeurbanne, France; emanuela.mattioli@univ-lyon1.fr

https://doi.org/10.58998/jnr3219
The Los Molles Formation in the Neuquén Basin, Argentina, is one of the few southern latitude locations that can shedlight on the diversity of Early–Middle Jurassic calcareous nannofossil assemblages. The recent establishment of a biostratigraphic framework based upon nannofossils allows us to evaluate the response of southern hemisphere environments to global changes, such as the early Toarcian Oceanic Anoxic Event (T-OAE) or the turnover in the nannoplankton community through the Early to Middle Jurassic, which occurred along with stable carbon isotope perturbations.
Previous investigations examined the expression of the T-OAE in the northern part of the basin and illustrated wellpreserved calcareous nannofossil assemblages in the south where there is a continuous record from the Pliensbachian
to the Aalenian.
The new Kalemen section in the Picún Leufú area, near the already known El Matuasto section, was studied for
calcareous nannofossils and geochemical analyses, including elemental composition, stable carbon isotopes measured
on organic matter, and total organic carbon (TOC) weight percent. Calcareous nannofossil assemblages show low diversity and abundance with some barren levels. However, identification of some events like the first occurrence (FO) of
Watznaueria britannica suggests that this outcrop is late Toarcian–Aalenian in age. Total organic carbon values fluctuate and can attain values as high as 5% in the studied interval, despite the overall high siliciclastic input. The carbon isotope ratio that was measured on organic matter also has significant fluctuations, making it difficult to identify any clear
trends. When compared to El Matuasto, Kalemen represents a deeper depositional environment with turbidite deposits.
Our approach adds a new piece to the paleoenvironmental puzzle of the Los Molles Formation, revealing importantvariations in sedimentation zones in close proximity to each other.

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Integrated biostratigraphy of the Upper Cretaceous–Eocene
deposits from Poiana Botizei-Botiza (Maramureș, Romania)
Carmen Mariana ChiraBabeş-Bolyai University, Faculty of Biology and Geology, Department of Geology, 400084 Cluj-Napoca, Romania; carmen.chira@ubbcluj.ro

Carlo Aroldi, Raluca Bindiu-HaitonicBabeş-Bolyai University, Faculty of Biology and Geology, Department of Geology, 400084 Cluj-Napoca, Romania;
carlo.aroldi@ubbcluj.ro; raluca.haitonic@ubbcluj.ro

Crina Miclaus

Al.I.Cuza University, Department of Geology, 700505 Iaşi, Romania; miclaus@uaic.roHoratiu ComanBabeş-Bolyai University, Faculty of Biology and Geology, Department of Geology, 400084 Cluj-Napoca, Romania;
horatiu.rares.coman@stud.ubbcluj.roAndrei Smeu

University of Bucharest, Faculty of Geology and Geophysics, Bucharest, Romania; asmeu8888@gmail.com

Geanina Zabulic, Flora ErbinucciBabeş-Bolyai University, Faculty of Biology and Geology, Department of Geology, 400084 Cluj-Napoca, Romania;
geanina.zabulic@stud.ubbcluj.ro; flora.erbinucci@stud.ubbcluj.ro

https://doi.org/10.58998/jnr3220
In the present study, detailed analyses of the Upper Cretaceous–Eocene deposits from Poiana Botizei and Botiza(Maramureş County, northwest Romania) focused mainly on calcareous nannofossils with some additional examination of foraminifera and ichnofossils. The Poiana Botizei Klippen Zone is part of the Pienide units in Romania and isa southeastward extension of the Pieniny Klippen Belt of the Western Carpathians. In the study area, the outcropping
formations are included into several south-vergent tectonic scales mainly consisting of “red beds” and “hieroglyphic
beds”. The “red beds” (Cretaceous–Paleocene) are predominantly marls with facies variations similar to the analogous“Puchow marls” in Slovakia and Poland. The color of the marls, although dominantly reddish, varies vertically and laterally depending upon physical, chemical, and biotic parameters. The depositional environment was probably bathyal
with limited and episodic input of fine-grained sedimentary clastic material. Because of the prevalence of quartz grains
and the absence of lithic fragments, the main source area of the clastics could be external to the East European Craton
or the inner Dacides.
The middle–upper Eocene succession consists of thin-bedded calcareous turbidites with predominantly Tc–e andTd–e Bouma intervals. Cross and convolute laminations, scour marks (groove and flute casts), and vertical burrows andtrails are common in some beds. Studies on provenance of clastic supply, based on orientation of sedimentary structures,show the primary direction of sediment influx was from south to north. The turbiditic depositional system can be considered one of transition from middle to outer fan into a well-oxygenated environment.
The foraminiferal samples were quite difficult to process in the laboratory due to their marly nature, but where present, benthic specimens dominated (agglutinated genera Bathysiphon, Placentammina, Haplophragmoides, Lituotuba,
and Recurvoides and some calcareous benthics of the genus Eponides). Planktonic foraminifera occurred in low percentages (consisting only of Heterohelix sp.). The foraminiferal assemblage indicates a bathyal environment above thecarbonate compensation depth.
At Botiza, the calcareous nannofossil assemblages contained very frequent Lucianorhabdus maleformis, Micula
murus, M. staurophora, M. cubiformis, and Watznaueria barnesiae, along with lower numbers of Broinsonia parca,
Cribrosphaerella ehrenbergii, and Microrhabdulus decoratus. Entire coccospheres were rarely present. In the lowest
part of the Poiana Botizei section, the “red marls” contain abundant and diversified calcareous nannofossils: Arkhangelskiella cymbiformis, A. maastrichtiensis, Micula staurophora, M. prinsii, M. murus, Ceratolithoides aculeus, Eiffellithus

INA1941

turriseiffelii, E. eximius, Prediscosphaera cretacea, Placozygus fibuliformis, B. parca, Lithraphidites carniolensis, M.
decoratus, C. ehrenbergii, and sometimes entire coccospheres. The calcareous nannofossil assemblages from the “redmarls”, both at Botiza and Poiana Botizei, indicate a Late Cretaceous (Maastrichtian) age.
The oldest Paleocene calcareous nannofossils are small coccoliths, Cruciplacolithus spp., Ericsonia spp., Markalius
spp., Biantholithus sparsus, and Zeugrhabdotus sigmoides, along with reworked Cretaceous taxa. Eocene calcareous
nannofossils include discoasters, Coccolithus pelagicus, and Reticulofenestra cf. dictyoda. A few samples were barrenof calcareous nannofossils.
The trace fossils were grouped toponomically into hypichnia, epichnia, and endichnia. Ethologically, the genera
were mixed domichnia–fodinichnia (Ophiomorpha, Thalassinoides, Arenicolites), fodinichnia (Rhizocorallium, Planolites, Taenidium), repichnia (Scolicia), and cubichnia (Lockeia) forms. These trace fossils suggest a Cruziana ichnofacies. The turbiditic depositional system was a transition from mid- to outer fan into a well-oxygenated environment.
Acknowledgements:

RBH acknowledges the financial support granted by Babeş-Bolyai University through the project SRG-UBB
32938/22.06.2023.

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Biometric analysis of the Maastrichtian Arkhangelskiellagroup in the Indian Ocean (ODP Hole 762C): Taxonomy andevolution
Meriam Chouar

University of Portsmouth, School of the Environment, Geography and Geosciences, Portsmouth, PO1 3QL, UK IGN; University of Copenhagen,1350 Copenhagen C., Denmark; m.chouar.geo@gmail.com

Nicolas Thibault

University of Copenhagen, IGN, 1350 Copenhagen C., Denmark; nt@ign.ku.dk

https://doi.org/10.58998/jnr3221
The Late Cretaceous genus Arkhangelskiella has been the object of numerous biometric studies due to its large variation in size and rim width throughout its stratigraphic range. Coincident with becoming a more significant componentof the nannofossil assemblage in the late Campanian of the North Atlantic, the genus significantly increased in size.
While some authors advocated against the presence of several morphotypes of the unique species Arkhangelskiellacymbiformis, others have identified three variants of this species in the North Sea (var. NT, var. N, and var. W), basedon the thickness of the rim and suggested dominance of these variants in distinct stratigraphic intervals of the Campanian–Maastrichtian. The definition of these variants was later emended based on variation in the length of the coccolith,
and they were elevated to species: A. cymbiformis sensu lato (var. NT), A. confuse (var. N), and A. maastrichtiensis (var.
W). In the Danish Basin, these morphotypes strongly overlap across all measured biometric parameters. The different
variants have been valued in terms of stratigraphy in the Danish Basin with var. N rising to dominance in the early
Maastrichtian and var. W dominant in the late Maastrichtian. It was also deemed necessary to introduce a fourth variant(var. SW) of average size and relatively thick rim that constitutes a transitional Maastrichtian form between var. N andvar. W. Variant NT was then considered a separate ancestor lineage, dominant in the Campanian.
In our study, morphological variations in A. cymbiformis were studied across the Maastrichtian within sedimentarydeposits of Ocean Drilling Program (ODP) Hole 762C (Indian Ocean), which has excellent stratigraphic constraints.
We measured coccolith length and width, rim width, and central area length and width on 1876 specimens from 32
samples. Coccolith length ranges from 7 μm to a staggering maximum of 18 μm. The results confirm that the length,
rim width, and central area opening are primary parameters for distinguishing between Arkhangelskiella variants. The
study confirms the presence of four overlapping variants with distinct stratigraphic occurrences: var. N, a small variantof <10 μm with relatively thick rim that is dominant in the early Maastrichtian; var. W, a large variant of >12 μm thatis dominant in the late Maastrichtian; and var. NT, of 8–14 μm, which bears a thin rim and wide-open central area andis present throughout the Maastrichtian. The transitional A. cymbiformis var. SW is needed to explain the overall stratigraphic evolution of these forms. While this evolutionary pattern and the upper limits in rim width and central opening
size are similar to those found in the Danish Basin, the upper limits in coccolith length are significantly larger by +2
μm, highlighting the difficulty in defining clear globally applied rules for the distinction of morphospecies. Comparison
between the percentage of the four variants and global climatic trends suggests that while the rise in dominance of thesmall (var. N) and very large (var. W) variants were favored during the early and late Maastrichtian cooling episodes,
the transitional var. SW dominated during the mid-Maastrichtian and late Maastrichtian warm episodes.

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Stratigraphy of the lower Danian in the Danish Basin:
Perspectives from calcareous nannofossils and stable
isotopes
Meriam Chouar

University of Portsmouth, School of the Environment, Geography and Geosciences, Portsmouth, PO1 3QL, UK IGN; University of Copenhagen,1350 Copenhagen C., Denmark; m.chouar.geo@gmail.com

Nicolas Thibault

University of Copenhagen, IGN, 1350 Copenhagen C., Denmark; nt@ign.ku.dk

Emma Sheldon

Geological Survey of Denmark and Greenland, Department of Geo-energy and Storage, 1350 Copenhagen K, Denmark; es@geus.dk

Kresten Anderskouv

University of Copenhagen, IGN, 1350 Copenhagen C., Denmark; ka@ign.ku.dk

https://doi.org/10.58998/jnr3222
The Danian Stage is characterized primarily by ecological recovery from the mass extinction at the Cretaceous/Paleogene boundary (K/Pg), as well as several enigmatic climatic events such as the Dan-C2 hyperthermal event and otherpotential short environmental perturbations from Deccan volcanism. However, the Danian Stage remains poorly studied
in the Boreal Realm. In this study, two Danian sections in the Danish Basin (onshore Denmark) are examined: Nye Kløv
(NW Jylland) and the recently drilled BH-01 core (north of Næstved, Sjælland). Isotopic records from both localities
allowed application of an age model via carbon isotope stratigraphy.
For the Danian of the Nye Kløv section, calcareous nannofossil quantitative abundance was integrated with previously established isotopic and biotic records. For the BH-01 core, new nannofossil biostratigraphy and carbon andoxygen isotope records on bulk carbonate were obtained. Correlation of the nannofossil recovery pattern and carbon
isotope records at Nye Kløv revealed a delayed recovery of the assemblages, with the increase of emergent species possibly linked to the early Danian Dan-C2 hyperthermal event. The new nannofossil biostratigraphy of the BH-01 core
links the lower Danian deposits at the classic locality of Stevns Klint to the middle Danian limestones at Faxe Quarry,
eastern Sjælland. This study, incorporating the absolute abundance of reworked Cretaceous species, Cretaceous survivor
taxa, and Danian emergent species, indicates a probable full recovery of the nannoplankton assemblages within 1 Myr
following the K/Pg boundary in the Danish Basin.

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The microscale exoskeletal reconstruction of the genus
Nannoconus - taxonomic insights
Rajkumar Chowdhury

Université Grenoble Alpes, Université Savoie Mont Blanc, CNRS, IRD, Université Gustave Eiffel, 38000 Grenoble, France;
rajkumar.chowdhury@univ-grenoble-alpes.fr

Fabienne Giraud, Alejandro Fernandez-Martinez

Université. Grenoble Alpes, Université. Savoie Mont Blanc, CNRS, IRD, Université. Gustave Eiffel, 38000 Grenoble, France;
fabienne.giraud-guillot@univ-grenoble-alpes.fr; Alex.Fernandez-Martinez@univ-grenoble-alpes.fr

Julio Cesar da-Silva, Redhouane Boudjehem, Anico Kulow, Maxime
Dupraz, Jean Louis Hazemann
Université. Grenoble Alpes, CNRS, Institut Néel, 38042 Grenoble, France; julio-cesar.da-silva@neel.cnrs.fr; redhouane.boudjehem@neel.cnrs.fr;
anico.kulow@neel.cnrs.fr; maxime.dupraz@neel.cnrs.fr; jean-louis.hazemann@neel.cnrs.fr

Baptiste Suchéras-Marx

Aix Marseille Université, CNRS, IRD, INRAE, CEREGE, Aix-en-Provence, France; sucheras-marx@cerege.fr

Gaston Garbarino

European Synchrotron Radiation Facility, 38043 Grenoble, France; gaston.garbarino@esrf.fr

Javier Perez

SWING Beamline, Synchrotron SOLEIL, L'Orme des Merisiers, 91190 Saint-Aubin, France; javier.perez@synchrotron-soleil.fr

Marie-Pierre Aubry

Rutgers University, Department of Earth and Planetary Sciences, New Brunswick, New Jersey 08854, USA; aubry@eps.rutgers.edu

https://doi.org/10.58998/jnr3223
Among calcareous nannofossils, the genus Nannoconus was the major biocarbonate producer of Early Cretaceous seas(~152 to ~120 Ma). With its heavy calcitic exoskeleton (~200–1100 picograms), it produced massive carbonate accumulations for approximately 30 million years. However, its taxonomic position and biological affinity are not well known.
A better understanding of the calcification process from the microstructural arrangement of the exoskeleton can help toclose this gap. The Nannoconus skeleton is physically characterized by the interlocking arrangement of calcitic laminae(length ~0.5–1 µm, thickness ~100–500 nm) around a central canal. This arrangement results from sets of laminae withtwo different angles of inclination. Different morphogroups of Nannoconus have been classified based on the variability of these angles. A set of ptychography X-ray computed tomography (PXCT) and synchrotron radiation at SWING
Beamline of SOLEIL (French synchrotron) was applied to several well-preserved Nannoconus skeletons in order tounderstand the microstructural arrangement at the nanometer level (finer than the thickness of an individual lamina).
The result of the experiment was a series of tomographic image slices (3D resolution ~30 nm) for the exoskeleton ofeach specimen. One lamina for each species of Nannoconus was virtually separated from the image slices using ORSDragonfly software. This lamina was used again to reconstruct virtually the entire exoskeleton of Nannoconus in thesame software. Based on these results, we propose two different models of construction:
Model 1: Two separate layers of plates are formed. The laminae in each layer have a specific inclination. The
entire exoskeleton is built by alternatively placing these two layers one above the other.
Model 2: One segment of laminae is created. Each segment is formed by alternately stacking laminae of two
different inclinations. The exoskeleton is built by joining several such segments.
Both models show that the exoskeleton was formed by the arrangement of laminae, but each model has a uniquegrowth pattern during calcification. However, model 2, in which segments constitute the building blocks of Nannoconus, agrees with scanning electron microscope (SEM) illustrations and descriptions of the structure of Nannoconus

INA1945

and other homococcoliths in the Order Braarudosphaerales, which includes the genus Braarudosphaera. Calcificationin the latter genus thus provides a good model for the calcification of Nannoconus on an external organic template. In
the case of Braarudosphaera, the template for each segment has a pentagonal shape and the laminae form on verticalcolumnar stacks. In the case of Nannoconus, the template for each segment is of triangular shape and the segments slant
in a sinistral direction.

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INA19

Calcareous nannofossils at the Cretaceous/Paleogene
boundary of the Northern Calcareous Alps (Wasserfallgraben section, Germany; Nussdorf section, Austria)
Stjepan Ćorić

GeoSphere Austria, Sedimentary Geology, Vienna, Austria; Stjepan.coric@geosphere.atMădălina-Elena Kallanxhi

Albanian Geological Survey, Tiranë, Albania; mada.geo2003@gmail.com

Iris Feichtinger

Natural History Museum Vienna, Geological-Palaeontological Department, Vienna, Austria; Iris.Feichtinger@NHM.AT

Anette Regelous, Marcel Regelous

GeoZentrum Nordbayern, University of Erlangen-Nürnberg, Erlangen, Germany; anette.regelous@fau.de; marcel.regelous@fau.de

Ulrich Teipel

Bavarian Environment Agency, Augsburg, Germany; Ulrich.Teipel@lfu.bayern.de

https://doi.org/10.58998/jnr3224
The Cretaceous/Paleogene (K/Pg) mass extinction is one of the five large mass extinctions that have occurred in Earth’s
history and the only major mass extinction event known so far to be connected to a major meteorite impact and simultaneously occurring flood basalt eruptions. The Wasserfallgraben section is the type section of the Campanian to Paleocene Nierental Formation, which belongs to the upper part of the Gosau Group of the Northern Calcareous Alps andconsists of deep-marine, hemipelagic, and turbiditic sediments. The Nierental Formation was deposited in a deep-water
environment that was the result of rapid subsidence due to subduction and tectonic erosion at the front of the AustroAlpine microplate.
The transition from the Maastrichtian to the Danian in the Nierental Formation can be documented by changes in
the calcareous nannofossil assemblage. Occurrences of Micula prinsii, Cribrosphaerella daniae, and other Late Cretaceous nannofossils occur in the lower two meters of the Wasserfallgraben section, allowing placement in the upper
part of the uppermost Maastrichtian nannofossil Subzone UC20d (equivalent to Subzone CC26b). Micula prinsii and
C. daniae were identified in all samples from the lowermost sample (profile height 200 cm) up to the K/Pg boundary(profile height 0 cm). Blooms of the genus Thoracosphaera (calcareous dinoflagellates), beginning with sample 32(profile height 0 cm), document the massive change in the nannofossil assemblage in the lowermost part of the Paleocene sediments. Sediments from this part of the section contain Biantholithus sparsus, Cyclagelosphaera alta, Prinsius
tenuiculus, and Neobiscutum parvulum. Based on the occurrences of these species and the absence of Cruciplacolithus
tenuis, this part of the succession can be attributed to nannofossil Zone NP1 (CP1a). A short bloom of Braarudosphaera
bigelowii and Braarudosphaera pentagonica, which were observed in sample 14 (profile height 68–80 cm), characterizes the lowermost part of the Danian.
Additionally, 33 samples were quantitatively investigated for calcareous nannofossils from the Nussdorf sectionin Austria, with 81 species identified within the Cretaceous part. Although they are not abundant, the marker species
restricted to the Maastrichtian are Ceratolithoides kamptneri, Chiastozygus antiquus, Lithraphidites quadratus, Micula
murus, M. prinsii, and Russellia bukryi. A total of 26 calcareous nannofossil species were identified in the five Paleogene samples. The calcareous dinoflagellates were counted separately under the Thoracosphaera spp. group, which
includes Calciodinellum albatrosianum, Cervisiella operculata, Thoracosphaera heimii, Pernambugia tuberosa, andThoracosphaera spp. The most abundant species in the Paleocene samples are Thoracosphaera spp. (77.10%), followed
by Cyclagelosphaera cf. alta (13.03%), which combined represent 90.13% of the assemblage.

INA19A revision of
Scyphosphaera

Quaternary

47

species

of

the

genus

Eric De Kaenel

DPR, Chemin sous la Roche 4b, 1185 Mont-sur-Rolle, Switzerland; edekaenel@bluewin.ch

https://doi.org/10.58998/jnr3225
The genus Scyphosphaera is perhaps one of the most understudied groups of coccolithophores due to its relative scarcity
in many stratigraphic sections. Polymorphism is one important feature of the scyphosphaerids as illustrated by Lohmann (1902) in his drawings of the type species S. apsteinii. Siesser (1998) indicated that 53 species had been describedfrom lower Eocene to Upper Pleistocene sediments. Many Quaternary Scyphosphaera species have been described in
the literature, but some may belong to the same coccosphere. To clarify the ranges of Quaternary Scyphosphaera andthe biostratigraphic value of some of these species, I undertook a detailed analysis of sediments from Ocean Drilling
Program (ODP) Leg 154 sites in the tropical Atlantic Ocean. I observed a total of 39 Scyphosphaera species in the Leg
154 Quaternary sediments. This degree of variation of forms is similar to that observed in Miocene or Pliocene sediments. I found no decrease in the number of Scyphosphaera species for the Late Pliocene (Subzone NN16B) or the Early
Pleistocene (Zone NN17 to Subzone NN19A). Based on this assessment, the number of Quaternary Scyphosphaera
species has so far been underestimated. All 39 species survived the early Quaternary cooling between 2.588 and 1.727
Ma (De Kaenel et al., 2024) and disappeared in the late Early Pleistocene (Calabrian). Only nine species are recorded in
the Holocene, and the youngest sample examined (1000 years) contained all nine: S. antilleana, S. apsteinii, S. aranta,
S. cohenii, S. elegans, S. galeana, S. magma, S. porosa, and S. recurvata.
I identified a total of nine Scyphosphaera groups (GR) in the Quaternary based on morphologic criteria and extinction levels. Species that disappear at the same time are placed in the same group and are thought to represent forms(formae) belonging to the same coccosphere and so to one unique species. The extinction of these groups occurs between
Subzones NN19B and NN21A with two groups surviving until today: the S. apsteinii group (GR1) and the S. porosagroup (GR2). The S. hemirana group (GR3) disappeared at 0.128 Ma (NN21B), the S. recta group (GR4) at 0.525 Ma(NN19F), the S. globulosa group (GR5) at 0.699 Ma (NN19F), the S. aequatorialis (GR6) at 0.731 Ma (NN19F), theS. pulcherrima group (GR7) at 0.966 Ma (NN19F), the S. campanula group (GR8) at 1.318 Ma (NN19D), and the S.
lagena group (GR9) at 1.643 Ma (NN19B). Each group of Scyphosphaera consists of lopadoliths of the same structure with some morphological variations in the shape of the margin or of the neck. A lopadolith with a neck was neverobserved in a group of lopadoliths without a neck. GR1 to GR5 include lopadoliths without a neck, and GR6 to GR9lopadoliths have necks. The highest occurrence of Scyphosphaera with a neck (GR6 at 0.731 Ma) occurs at the baseof the Middle Pleistocene, just above the Matuyama/Brunhes magnetochron boundary, and divides the Quaternary into
two main intervals (Early Pleistocene and Middle–Late Pleistocene). The other six Pleistocene groups provide usefuladditional biohorizons to subdivide the Quaternary calcareous nannofossil zonation.
References:
De Kaenel, E., Bord, D., Menini, A. & Martignier, A. 2024. Binasphaera nucleonimbiformis, a unique new nannofossil genus and species describedfrom the western equatorial Atlantic Ocean (ODP Leg 154 Site 926) and observed globally. Journal of Nannoplankton Research, 42(1): 55–83.
https://doi.org/10.58998/jnr3348
Lohmann, H. 1902. Die Coccolithophoridae, eine Monographie der Coccolithen bildenden Flagellaten, zugleich ein Beitrag zur Kenntnis des Mittelmeerauftriebs. Archiv für Protistenkunde, 1: 89–165.
Siesser, W.G. 1998. Calcareous nannofossil Genus Scyphosphaera: structure, taxonomy, biostratigraphy, and phylogeny. Micropaleontology, 44(4):351–384. http://doi.org/10.2307/1486040

48

INA19

Calcareous nannofossil paleoceanography across Oceanic
Anoxic Event 3: From local to global perturbations
Elisabetta Erba

University of Milan, Department of Earth Science, 20133 Milan, Italy; elisabetta.erba@unimi.it

Francesco Miniati

Institute of Geosciences and Earth Resources (IGG), National Research Council of Italy (CNR), 50121 Firenze, Italy; francesco.miniati@igg.cnr.it

Cinzia Bottini

University of Milan, Department of Earth Science, 20133 Milan, Italy; cinzia.bottini@unimi.it

https://doi.org/10.58998/jnr3226
The Late Cretaceous was punctuated by several periods of global perturbations in the climate–ocean system that led towidespread deposition of organic carbon-rich marine black shales known as oceanic anoxic events (OAEs). The OAE3,
which represents the youngest Cretaceous episode of anoxia and is in the Coniacian–Santonian, was confined to theequatorial Atlantic Ocean and adjacent basins rather than being global in scale. We focused on nannofossil paleoceanography of the late Turonian to early Campanian time interval and applied quantitative analyses to assess the responseof calcareous nannoplankton to paleoenvironmental changes across OAE3. The study was conducted on sites from the
Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP) situated in the equatorial and southern Atlantic
Ocean and the Indian Ocean, as well as land sections from the Anglo-Paris Basin. A detailed, revised, and high-resolution nannofossil biostratigraphy of the selected sites enabled correlations at a supra-regional scale.
Quantitative analyses allowed us to characterize paleotemperature and nutrient changes before, during, and after
OAE3. Nannofossil-based paleotemperatures varied depending upon the cool-water taxa considered. However, warm
conditions that were interrupted by brief cooling episodes in the Coniacian–early Santonian interval were followed bya generalized and longer term cooling that began in the middle Santonian. Regarding paleofertility, the nannofossil assemblages exhibit very different patterns at the various sites, suggesting that OAE3 was not characterized by a global
fertilization episode.
We identified relatively large fluctuations in abundance of the genera Micula and Marthasterites, which correlatewith coeval peaks described in the literature, albeit with different abundance values at various sites and sections. Discrete Marthasterites (M. furcatus) and Micula (M. staurophora) “acmes” were identified across OAE3. The paleoecological affinities of Micula and Marthasterites remain elusive, but their distinctive fluctuations indicate that there were
profound paleoceanographic changes at specific times. The onset of OAE3 coincides with a major increase in abundance(and local dominance) of M. furcatus, suggesting the rapid establishment of new and peculiar paleoceanographic conditions at a widespread to global scale. The most altered paleoceanographic conditions occurred during the core of OAE3
as characterized by the synchronous maximum abundance (climax) of M. staurophora on a global scale. In addition totheir value for paleoenvironmental reconstructions, the Micula and Marthasterites “acmes” are useful for the biostratigraphic characterization of the Turonian/Coniacian, Coniacian/Santonian, and Santonian/Campanian boundaries. These“acmes” might be introduced as additional events in future nannofossil zonations for the Late Cretaceous.

INA1949

Phosphate-limiting conditions induce cell volume increasein natural coccolithophore populations
Miguel J. Frada

Hebrew University of Jerusalem, Department of Ecology, Evolution and Behavior, Alexander Silberman Institute of Life Sciences, Jerusalem,
Israel; The Interuniversity Institute for Marine Sciences in Eilat, Eilat, Israel; miguel.frada@mail.huji.ac.il

Sabine Keuter

University of Hamburg, Department of Microbiology and Biotechnology, 22609 Hamburg, Germany; keuter@gmx.org

Gil Koplovitz

The Interuniversity Institute for Marine Sciences in Eilat, Eilat, Israel; gil.koplovitz@mail.huji.ac.il

https://doi.org/10.58998/jnr3227
Coccolithophores are a key functional phytoplankton group that produce distinctive minute calcite plates (coccoliths)
covering the cell surface. Calcification and subsequent export of coccoliths reduce alkalinity in the surface ocean andcause a net release of CO2 into the atmosphere, counteracting the CO2 drawdown by photosynthesis, thus constituting
an important pathway of the global carbon cycle. Experiments in vitro indicate that the coccosphere size and coccolith
length of Gephyrocapsa huxleyi increase when phosphate (P) is limited and decrease when nitrogen (N) is limited,
relative to exponential cell growth in nutrient-replete conditions. However, variations occur between natural and experimental conditions. To test whether coccosphere size variations that occur in nature relate to nutrient availability,
we examined coccolithophore communities in two oligotrophic ecosystems with marked seasonal variability: the Gulfof Aqaba (GoA) in the northern Red Sea and the Eastern Mediterranean (EM). In the GoA, we found that G. huxleyi
cells are larger during the summer in the stratified layer, whereas winter cells are smaller in the mixed layer. Bioassays
indicate that during the summer, cells are primarily P-limited, whereas nutrient limitation in the winter is absent or weak.
Critically, no correlation between coccosphere size and coccolith length was detected. Similar size variations were detected for the similar species Gephyrocapsa ericsonii. The seasonal pattern in G. huxleyi size was the opposite in the EM.
Coccospheres were larger in the mixed layer during winter and smaller during the stratified summer, which coincides
with the prevalent pattern of limitation. The EM is permanently P-limited across all seasons, but during the summer, N
limitation often predominates over P limitation. These results indicate that nutrient availability is a major regulator of
coccolithophore size in marine ecosystems.

50

INA19

New insights on calcareous nannofossil biostratigraphy andpaleoecology around the Pliensbachian/Toarcian boundary
in the South Iberian paleomarginÁngela Fraguas

University King Juan Carlos, Department of Biology, Geology, Physics and Inorganic Chemistry and Research Group in Earth Dynamics and Landscape Evolution (DYNAMICAL), 28933 Móstoles, Spain; angela.fraguas@urjc.es

Luis Nieto, José Miguel Molina, Matías Reolid

University of Jaén Campus Universitario Las Lagunillas, Department of Geology and Center of Advanced Studies in Earth Sciences, Energy andEnvironment (CEACTEMA), 23071 Jaén, Spain; lmnieto@ujaen.es; jmmolina@ujaen.es; mreolid@ujaen.es

https://doi.org/10.58998/jnr3228
Calcareous nannofossils have proved to be one of the most useful tools for dating Mesozoic marine rocks, especiallyin those areas where ammonites are very scarce or absent. This is the case for two stratigraphic sections in the Betic
External Zone: Sierra Pelada (PEL) in the median Subbetic and Guarrumbre (G) in the external Subbetic. The uppermost Pliensbachian–lower Toarcian, pre-Jenkyns Event materials from these sections have been dated with precision
with calcareous nannofossils using the biostratigraphic scheme of Ferrerira et al. (2019) for the western Tethys. In the
PEL section, the boundary between Subzones NJT5b and NJT5c was established based on the first occurrence (FO) of
Zeugrhabdotus erectus, which also enabled the approximation of the Pliensbachian/Toarcian boundary. At the G section, Subzones NJT5a, NJT5b, NJT5c, and NJT6a were identified using the FOs of Lotharingius crucicentralis (latest
Pliensbachian), Z. erectus, and Carinolithus superbus (early Toarcian).
The results of the quantitative analysis performed on calcareous nannofossils from the PEL and G sections can help
us decipher their paleoecological affinities around the Pliensbachian/Toarcian boundary, a time interval marked by environmental and climatic changes with an increase in temperature and a negative carbon isotope excursion (CIE). Coinciding with the negative CIE, there was a decrease in the relative abundance of Calcivascularis jansae, which probably
thrived under relatively cool temperatures and oligotrophic conditions (Fraguas et al., 2021) and can be observed in both
sections. Furthermore, a sharp increase in the relative abundances of Mitrolithus lenticularis and Crepidolithus crucifer,
which could thrive under warm and mesotrophic conditions, was noticed only at PEL, which was located in a more distal
paleogeographic position than G with respect to the South Iberian paleomargin. According to Peti & Thibault (2022),
these two species thrived predominantly in open-ocean settings. In both sections, the opportunistic taxon Lotharingius
hauffii, together with other species of the genus Lotharingius and the recovered C. jansae, dominated the nannofossil
assemblages above the negative CIE and the Pliensbachian/Toarcian boundary.
References:
Ferreira, J., Mattioli, E., Sucherás-Marx, B., Giraud, F., Duarte, L.V., Pittet, B., Suan, G., Hassler, A. & Spangenberg, J.E. 2019. Western Tethys Earlyand Middle Jurassic calcareous nannofossil biostratigraphy. Earth-Science Reviews, 197: 102908. https://doi.org/10.1016/j.earscirev.2019.102908
Fraguas, Á., Gómez, J.J., Goy, A. & Comas-Rengifo, M.J. 2021. The response of calcareous nannoplankton to the latest Pliensbachian–Early Toarcian
environmental changes in the Camino Section (Basque Cantabrian Basin, northern Spain). Geological Society, London, Special Publications, 514:
31–58. https://doi.org/10.1144/SP514-2020-256
Peti, L. & Thibault, N. 2022. Early Jurassic coccolith diversification and response to pre-Toarcian environmental changes: A perspective from theParis Basin. Marine Micropaleontology, 177: 102173. https://doi.org/10.1016/j.marmicro.2022.102173

INA1951

Early Miocene microfossils from Marmorito (Italy)
Shun Fujiyama

Yamagata University, Graduate School of Science & Engineering, 1-4-12 Kojirakawa-machi, Yamagata 990-8560, Japan;s235447m@st.yamagata-u.ac.jp

Luca Pellegrino, Francesca Lozar

Università degli Studi di Torino, Departimento di Scienze della Terra, 10125 Torino, Italy; lu.pellegrino@unito.it; francesca.lozar@unito.it

Kenta Abe

Senzaki Co., Ltd., 3-5-2 Izumihoncho, Komae, Tokyo 201-0003, Japan; 104b0154@gmail.com

Richard W. Jordan

Yamagata University, Faculty of Science, 1-4-12 Kojirakawa-machi, Yamagata 990-8560, Japan; sh081@kdw.kj.yamagata-u.ac.jp

https://doi.org/10.58998/jnr3229
In previous studies, the Marmorito sediments in northwest Italy were determined to be Early Miocene (Aquitanian–Burdigalian) in age, based on foraminifera and diatoms. However, there have been few investigations on other microfossil
groups. Samples from 28 diatomaceous layers were obtained in February 2019 and prepared as permanent mounts forthe light microscope (LM) and stubs for the scanning electron microscope (SEM). Observations on the calcareous nannofossils revealed the presence of coccospheres of Tergestiella sp., Coccolithus pelagicus, Reticulofenestra minuta, R.
haqii, and Cyclicargolithus floridanus, which suggests that these species were deposited in situ (i.e., not reworked).
However, the assemblages also include reworked Cretaceous and Paleogene forms. Siliceous scales of the putative
haptophyte Macrora stella were encountered, particularly in the lower Burdigalian. Diverse silicoflagellate assemblages
were comprised of Naviculopsis, Mesocena (Bachmannocena), Corbisema, Distephanopsis, Dictyocha, and Stephanocha, and they represent a time close to the extinctions of Corbisema and Naviculopsis and before the first appearance of
Caryocha. Chrysophyte cysts were also observed and assumed to be associated with river outflow. Diatom assemblages
contained a lot of Chaetoceros resting spores, as well as attached and benthic taxa, with few (if any) offshore taxa, whichcollectively suggests a shallow shelf assemblage. Sponge spicule assemblages were mainly composed of oxeas, styles,
sigmas, and spherasters that seemingly originating from shallow- and deep-water sponges.
From this holistic approach, our microfossil data show that the Marmorito sediments were likely deposited on thecontinental slope, given the presence of deep-water (e.g., some of the sponges) and offshore (silicoflagellates) forms, butwith significant input from river outflow (chrysophytes), as well as coastal and shelf assemblages (diatoms and some of
the coccolithophorids). In addition, monospecific Ethmodiscus layers may suggest rapid deposition of seasonally stratified oligotrophic waters or selective preservation through sediment winnowing.

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INA19

Early Aptian Oceanic Anoxic Event 1a (OAE1a): Evidence
based on calcareous nannofossils in the Qaleh Zoo section,
central Kopet Dagh, Iran
Azam Gholamifard

Shahid Beheshti University, Department of Sedimentary Basins and Oil, Faculty of Earth Science, Tehran, Iran; a_gholamifard@sbu.ac.ir

Anoshirvan Lotfali Kani

Shahid Beheshti University, Department of Sedimentary Basins and Oil, Faculty of Earth Science, Tehran, Iran; a-kani@sbu.ac.ir

Azam Mahanipour

University of Kerman, Department of Geology, Faculty of Science, Shahid Bahonar Kerman, Iran; A_mahanipour@uk.ac.ir

Amirmohammad Jamali

National Iranian Oil Company, Exploration Directorate, Tehran, Iran; amjgeo@yahoo.com

Fariba Foroughi

University of Tehran, School of Geology, College of Science, Tehran, Iran; f.foroughi@ut.ac.ir

https://doi.org/10.58998/jnr3230
This study examines a marine sedimentary succession from the middle part of the Sarcheshmeh Formation with the aimof recording the early Aptian Oceanic Anoxic Event (OAE) 1a in the Qaleh Zoo section in the central part of the Kopet
Dagh Basin in northeastern Iran. The OAE1a was recorded on a global scale during the early Aptian in the nannofossil
Subzone NC6B. In this study based on calcareous nannofossils, the interval from the uppermost part of Subzone NC6A
to the lowermost part of Subzone NC7A (early Aptian) was examined in the Sarcheshmeh Formation. For the identification of OAE1a, calcareous nannofossil paleoecology and calcium carbonate content were analyzed. The rare presence orabsence of nannoconids in Subzone NC6B, together with the lowest calcium carbonate values, indicates the presence of
OAE1a in the Sarcheshmeh Formation (55–180 m in the studied interval). Considering the calcareous nannofossil data
and the calcium carbonate content of the samples, OAE1a was placed in the middle part of the Sarcheshmeh Formation,
which is equivalent to the event west of the Kopet Dagh Basin in the Takal Kuh section (Mahanipour et al., 2011).

References:
Mahanipour, A., Mutterlose, J., Kani, A. & Adabi, M.H. 2011. Palaeoecology and biostratigraphy of early Cretaceous (Aptian) calcareous nannofossils and the δ13Ccarb isotope record from NE Iran. Cretaceous Research, 32(3): 331–356. https://doi.org/10.1016/j.cretres.2011.01.006

INA1953

Using extraterrestrial 3He to reconstruct terrigenous fluxes
and their impacts on marine primary productivity and carbon
burial during OAE2 in the Vocontian Basin (SE France)
Blandine Godet

Université de Lorraine, CRPG, CNRS, 54500 Vandoeuvre-lès-Nancy, France; blandine.godet@univ-lorraine.fr

Pierre-Henri Blard

Université de Lorraine, CRPG, CNRS, 54500 Vandoeuvre-lès-Nancy, France; Université Libre de Bruxelles, Laboratoire de Glaciologie, Department of Geosciences, Environment, Society, Brussels, Belgique; pierre-henri.blard@univ-lorraine.fr

Guillaume Suan

Université de Lyon 1, ENSL, CNRS, LGL-TPE, 69622, Villeurbanne, France; guillaume.suan@univ-lyon1.fr

Baptiste Suchéras-Marx

Aix Marseille Université, CNRS, IRD, INRAE, Collège de France, CEREGE, 13400 Aix-en-Provence, France; sucheras-marx@cerege.fr

Laurent Riquier

Sorbonne Université, ISTeP, SU/CNRS, 75005 Paris, France; laurent.riquier@sorbonne-universite.fr

Bouchaïb Tibari

Université de Lorraine, CRPG, CNRS, 54500 Vandoeuvre-lès-Nancy, France; bouchaib.tibari@univ-lorraine.fr

https://doi.org/10.58998/jnr3231
The Mesozoic was punctuated by several oceanic anoxic events (OAEs) that were characterized by widespread blackshale deposition and global carbon cycle perturbations. Among them, OAE2, spanning the Cenomanian/Turonian boundary (~94 Ma), has been identified as one of the most severe OAEs of the Mesozoic. Lasting ~600 kyr, this event is marked
by a global >2‰ positive excursion in the δ13C signature of both carbonates and organic matter. This has been interpreted
to reflect a massive burial of isotopically light organic carbon that was driven by deoxygenation of ocean bottom water.
Previous models suggested that volcanism related to large igneous provinces (LIPs) increased atmospheric and oceanic
CO2 concentrations, thereby increasing nutrient input into the ocean, increasing marine primary production, and decreasing seawater oxygenation. This volcanism also disturbed the climate by increasing precipitation and thus weathering.
However, the respective roles of weathering and detrital fluxes on marine primary productivity and organic carbon burial
during OAE2 remain highly debated, mainly due to the lack of high-resolution chronologies. In this study, we performed
new extraterrestrial 3He (3HeET) measurements on hemipelagic marine samples from Pont d’Issole (Vocontian Basin, SE
France) in order to reconstruct carbonate and organic carbon contents, and terrigenous sedimentation rates and fluxes
across OAE2. Combined with organic matter content, trace metal concentrations, and nannofossil fluxes, this method allowed us to trace sources and variations of each of the three sedimentary components during the event.
Our results reveal that over 70% of the 3He in the analyzed samples is extraterrestrial in origin. Assuming a constantflux of interplanetary dust particles, the 3HeET concentrations allowed us to reconstruct relative changes in sedimentation rates at an unprecedented high resolution (every 15 cm). Our preliminary results suggest that there were changes
in the variability of terrigenous and carbonate depositional fluxes across OAE2. Indeed, prior to OAE2 and at its onset,
sediments are characterized by constant terrigenous input across different carbonate-rich and carbonate-poor lithologies, whereas total sedimentation plummeted (from 17 to 2 g/cm²/kyr). The beginning of the event was thus marked bya collapse of carbonate net deposition. In contrast, sediments from the Plenus Cold Event (colder and more oxygenatedperiod within early OAE2) and from the Cenomanian/Turonian boundary show variations in both terrigenous and carbonate fluxes (from 0.2 to 2 g/cm²/kyr and from 0.5 to 8 g/cm²/kyr, respectively). In both cases, reconstructed organic
matter accumulation rates peaked during short-lived pulses. The implications of our new nannofossil and 3HeET data will
be discussed in the context of the debated role of increased detrital input on marine primary productivity and organiccarbon burial during OAE2.

54

INA19

Coccolithophore
assemblages
andpaleoceanographic
dynamics at IODP Site U1385: Insights from the Pliocene–
Pleistocene transition (western Iberian margin)
María González-Martín

Universidad de Salamanca, Department of Geology, 37008, Salamanca, Spain; mariaglezmartin@usal.es

Patrizia Maiorano, Maria Marino

Universitá degli Studi di Bari Aldo Moro, Dipartimento di Scienze Della Terra e Geoambientali, 70125 Bari, Italy; patrizia.maiorano@uniba.it;
maria.marino@uniba.it

Barbara Balestra

American University, Department of Environmental Science, Washington D.C. 20016, USA; balestra@american.edu

José A. Flores

Universidad de Salamanca, Department of Geology, 37008, Salamanca, Spain; flores@usal.es

https://doi.org/10.58998/jnr3232
This study investigates coccolithophore assemblages from the Pliocene–Pleistocene transition in an ocean sediment corefrom International Ocean Discovery Program (IODP) Site U1385 (Expedition 397), located on the western Iberian margin and retrieved at a depth of 2590 meters below sea level (mbsl). The samples, which were collected over 109 meters(215.5–324.5 meters below seafloor [mbsf]) with an average sedimentation rate of 10 cm/kyr, should allow us to identify
the most relevant signatures of astronomical cycles. Samples were prepared using the random sedimentation techniquedescribed by Flores & Sierro (1997), and a quantitative analysis was carried out on the entire assemblage.
Biostratigraphic events based on the quantitative distribution of several species of the genus Discoaster (highest
occurrences of D. pentaradiatus, D. surculus, and D. tamalis) were recognized and used to establish a preliminary age
model for the studied interval. The coccolithophore assemblage is mainly composed of small placoliths (<3 µm), followed by medium-sized placoliths (3–5 µm), and Florisphaera profunda. The abundances of small and medium placoliths show clear anti-correlation, which, together with the patterns of N ratio (Reticulofenestra spp./Reticulofenestra spp.
+ F. profunda) and total coccolith abundance, may provide information about paleoproductivity and nutricline variations
through time. The overall results will provide insight into the most important variations of coccolithophore assemblage
productivity and oceanographic conditions during the Pliocene–Pleistocene transition that was a crucial time for Earthclimate changes.
References:
Flores, J.A. & Sierro, F.J. 1997. Revised technique for calculation of calcareous nannofossil accumulation rates. Micropaleontology, 43(3): 321–324.
https://doi.org/10.2307/1485832

INA1955

Environmental influences on coccolithophore distribution
and abundance in the water column of the western Iberianmargin (August 2022)
María González-Martín

Universidad de Salamanca, Department of Geology, 37008, Salamanca, Spain; mariaglezmartin@usal.es

Andrés S. Rigual-Hernández

Universidad de Salamanca, Department of Geology, 37008, Salamanca, Spain; arigual@usal.es

Emilia Salgueiro, Fátima Abrantes

Instituto Português do Mar e da Atmosfera, 1495-165 Alges, Portugal; emilia.salgueiro@ipma.pt; fabrantes22@gmail.com

José A. Flores

Universidad de Salamanca, Department of Geology, 37008, Salamanca, Spain; flores@usal.es

https://doi.org/10.58998/jnr3233
This study investigates the abundance, composition, and biogeographical distribution of coccolithophores in the watercolumn of the northwestern Iberian coastal upwelling system during late summer 2022. The coccolithophore data werecompared with physical, chemical, and biological parameters measured in situ to evaluate the influence of the environment on coccolithophore distribution. Additionally, coccolithophore data were compared with satellite data (NASA
Ocean Biogeochemical Model [NOBM] and NASA Moderate-Resolution Imaging Spectroradiometer [MODIS]) andthe upwelling index (UI) in the study area. The results reveal a latitudinal and longitudinal gradient in coccolithophore
abundance with peaks towards the north and east. This indicates that the stations closest to the coast (CA-7, CA-8, andCA-4) are most affected by coastal upwelling, with cooler surface temperatures and higher fluorescence and turbidity
values. Moreover, our data suggest that the source of the upwelled water in the north (Eastern North Atlantic Central
Waters of subpolar origin, ENACWsp) is different from that in the south (ENACW of subtropical origin [st]). The significant correlation between the upwelling index and the total abundance of coccoliths and coccospheres underlines theimportant role of upwelling mechanisms in controlling the abundance and spatial distribution of coccolithophores along
the western Iberian margin. Furthermore, the significant correlation between coccolithophore abundance and fluorescence (Chl-a) and turbidity suggests that coccolithophores account for a substantial fraction of the primary productionin the region.
The affinity of certain species to specific environmental conditions supports their use as paleoenvironmental indicators in the study area. In particular, the small Noelaerhabdaceae group (sum of the small Gephyrocapsa group and Emiliania huxleyi) is proposed as a proxy for primary productivity (PP) and enhanced upwelling intensity (UI > 0), whereas
Florisphaera profunda appears to be associated with conditions of upwelling relaxation, stratified water column (deepthermocline), and low productivity in the upper photic zone. Discrepancies between our in situ observations and satellite data are attributed to the limited capacity of satellites to detect subsurface biological processes. In addition, thisstudy supports the viability of using the N ratio in water column samples, as opposed to only in sediments as suggested
by previous work. Overall, this research contributes to a deeper understanding of primary productivity on the western
Iberian margin during the upwelling season and emphasizes the crucial role of coccolithophores in paleoenvironmental
reconstructions.

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Morphometric analysis of the calcareous nannofossil group
Aspidolithus in the lower Campanian: Implications fortaxonomy
Paula Granero

University of Vienna, Department of Geology, 1090 Vienna, Austria; paula.granero.ordonez@univie.ac.at

Adam Wierzbicki

Jagiellonian University in Krakow, Institute of Geological Sciences, Krakow, Poland; adam.wierzbicki@uj.edu.pl

Michael Wagreich

University of Vienna, Department of Geology, 1090 Vienna, Austria; michael.wagreich@univie.ac.athttps://doi.org/10.58998/jnr3234
Changes in the coccolith morphometry of the Aspidolithus parcus group have been used to distinguish biostratigraphically relevant subspecies for the Late Cretaceous. However, insufficiently detailed morphometric analyses have hindered
the establishment of statistical differentiation among the subspecies. Consequently, the taxonomic classification of thisgroup remains ambiguous, which also affects the accuracy of biostratigraphic correlations. In this study, a morphometricanalysis of samples from the lower Campanian of the Loibichl section (Rhenodanubian Flysch Zone, Austrian Alps) was
performed that focused on the Aspidolithus group. Semi-quantitative analyses of the nannofossil assemblages allowed
the calculation of paleoenvironmental indices. In addition, 1021 well-preserved specimens of the Aspidolithus groupwere measured for several key parameters: (1) the maximum coccolith length (L), (2) the maximum coccolith width(W), (3) the width of the outer rim versus the small diameter of the central area (b/a), and (4) the number and arrangement of perforations in the central area. The main objective was to identify significant differences between Aspidolithus
morphotypes and to explore possible factors influencing size variation within this group. In addition, we analyzed
CaCO3 content and stable isotope ratios of δ13C and δ18O to aid stratigraphic and paleoecological interpretations.
Five distinct morphotypes were identified: Aspidolithus enormis subsp. 1, A. enormis subsp. 2, A. parcus expansus,
A. parcus parcus, and A. parcus constrictus. Morphometric analyses revealed significant taxonomic differentiation between the “small” A. enormis (<8–8.5 µm in length) and the “large” A. parcus group (≥8–8.5 µm in length). However,the study found no clear patterns that naturally classify the “subspecies” (A. parcus expansus, A. parcus parcus, andA. parcus constrictus) within the A. parcus group. These morphotypes appear to be an evolutionary lineage, probably
driven by the global cooling that began in the late Santonian. Moreover, it was observed that the dimensions of the central area, represented by the value of the ratio b/a, correlate with surface temperature values. An in-depth examinationof global versus regional environmental influences is essential to fully understand these findings. Therefore, calcareous
nannofossil samples from the Smoky Hill Member of the Niobrara Formation (Kansas, USA) are being analyzed toconfirm this impact on size variation.

INA1957

Recent progress in the studies of Braarudosphaera bigelowii
Kyoko Hagino

Kochi University, Marine Core Research Institute, Monobe B200, Nankoku, Kochi, Japan; hagino@kochi-u.ac.jp

https://doi.org/10.58998/jnr3235
Braarudosphaera bigelowii (Gran & Braarud, 1935) Deflandre has long been considered a coastal–neritic dweller because pentaliths of B. bigelowii are usually found only from coastal–neritic marine sediments deposited on continental
shelves. However, the discovery of a symbiotic relationship between an unidentified species, which is closely related
to B. bigelowii in 18S rDNA sequence, and cosmopolitan nitrogen-fixing cyanobacterium UCYN-A (Thompson et al.,2012) suggests that extant Braarudosphaera specimens are widely distributed from coastal seas to open oceans, andBraarudosphaera plays an important role in the ocean nitrogen cycle. Moreover, a recent study on the established culture strain of B. bigelowii s.s. (18S rDNA genotype III) revealed that UCYN-A2 (one of the nifH genotypes of UCYNA) has evolved beyond endosymbiosis and is in the early stages of developing into a N2-fixing organelle (nitroplast)(Coale et al., 2024). This talk will review the progress in the studies of B. bigelowii and nitroplasts (UCYN-A) over a
decade, discuss taxonomic issues of Braarudosphaera, and present the remaining challenges to be solved in Braarudosphaera research.
References:
Coale, T.H., Loconte, V., Turk-Kubo, K.A., Vanslembrouck, B., Mak, W.K.E., Cheung, S., Ekman, A., Chen, J.-H., Hagino, K., Takano, Y., Nishimura, T., Adachi, M., Gros, M. L., Larabell, C. & Zehr, J.P. 2024. Nitrogen-fixing organelle in a marine alga. Science, 384: 217–222. https://doi.
org/10.1126/science.adk1075
Thompson, A.W., Foster, R.A., Krupke, A., Carter, B.J., Musat, N., Vaulot, D., Kuypers, M.M.M. & Zehr, J.P. 2012. Unicellular cyanobacterium
wymbiotic with a single-celled eukaryotic alga. Science, 337: 1546–1550. https://doi.org/10.1126/science.1222700

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Size-fraction coccolith stable isotopes and Sr/Ca from the
Miocene to Recent
Emma Hanson

University of Birmingham, School of Geography, Earth and Environmental Sciences, Birmingham, B15 2TT UK; e.hanson.1@bham.ac.uk

Tom Dunkley Jones, Sushanth Gattupalli, Amy Jones

University of Birmingham, School of Geography, Earth and Environmental Sciences, Birmingham, B15 2TT UK; t.dunkleyjones@bham.ac.uk;
sxg268@student.bham.ac.uk; amypatriciajones@gmail.com

Mariem Saavedra-Pellitero

University of Portsmouth, School of the Environment, Geography & Geosciences, Portsmouth, PO1 2UP, UK; mariem.saavedra-pellitero@port.ac.uk

Sophie Slater, Caroline Lear

Cardiff University, School of Earth and Environmental Sciences, Cardiff, CF10 3AT, UK; SlaterS3@cardiff.ac.uk; LearC@cardiff.ac.uk

https://doi.org/10.58998/jnr3236
The preservation of coccoliths in marine sediments makes them an excellent recorder of surface ocean environmental
change through geologic time. Geochemical analyses of coccolith-rich sediment fractions have recently been the basis
for determining biotic responses to paleoenvironmental change, most notably through δ13C stable isotopic analysis ofcoccolith size-separated microfractions. A marked isotopic divergence, also known as vital effects, in coccolith δ13C
between small (<4 µm), lightly calcifying forms (e.g., Gephyrocapsa oceanica and Emiliania huxleyi) and large (~7–10µm), heavily calcifying forms (Calcidiscus leptoporus and Coccolithus pelagicus) is noted in extant species in culture
studies. This effect originated during the Late Miocene (7–5 million years ago) and has been linked to a decline in atmospheric CO2, causing a reallocation of carbon from calcification to photosynthesis in the coccolithophore cell during
coccolithogenesis that particularly affected larger cells.
To investigate how these isotopic divergences may have been influenced by climatic events and nannofossil evolutionary changes, we generated a long-term record of coccolith geochemistry, including oxygen and carbon isotopes andstrontium/calcium, from the Miocene to Recent (~10 to 0.1 million years ago). All samples that capture the emergenceof these vital effects come from International Ocean Discovery Program (IODP) Site U1482 (Expedition 363) on thenorthwest Australian continental margin. A further high-resolution record from the same site was generated that spans
the Pliocene–Pleistocene transition (3.01 to 1.38 million years ago). A novel technique allows for the rapid separationof coccolith-rich sediments into very fine and very coarse fractions, allowing for the generation of high-resolution sizespecific coccolith geochemistry records over the two time periods. Further honing of this method will enable the further
use of coccolithophore isotopes, particularly when paired with the alkenone CO2 proxy, which would allow us to study
coccolithophore carbon limitation through time.

INA1959

Calcareous nannoplankton and εNd as paleogeographic
proxies: A case study from the Langhian junction of the
Indian Ocean, the Mediterranean, and the Paratethys
Katarína Holcová

Charles University, Institute of Geology and Paleontology, 128 43 Prague, Czech Republic; holcova@natur.cuni.cz

Filip ScheinerCharles University, Institute of Geology and Paleontology, 128 43 Prague, Czech Republic; scheinef@natur.cuni.cz

https://doi.org/10.58998/jnr3237
The location of marine seaways or gateways between the Mediterranean, the Paratethys, and the Indian Ocean fromthe late Burdigalian to the Serravallian is still a matter of scientific debate, although several paleogeographic reconstructions have attempted to assess this issue in recent decades (Popov et al., 2004; Bialik et al., 2019). Unfortunately,
due to intensive tectonic activity and denudation of the Miocene sedimentary cover in the Eurasian area, only isolated
relicts of the original marine basins, including those representing communication corridors, have been preserved. As aresult, the only original record available is that of isolated relics, which in some areas are completely absent. However,various paleobiological proxies (e.g., migration paths of indicative species and distribution of indicative assemblages)
can be used to partially reconstruct the paleogeographic setting. In addition, Nd isotope systematics can be helpful, as
143
Nd/144Nd is one of the most prominent paleoceanographic proxies for tracing water masses (von Blanckenburg, 1999;
Bialik et al., 2019).
In this context, our study aims to evaluate the contribution of calcareous nannofossil assemblage analysis together
with the 143Nd/144Nd proxy to reconstruct communication corridors in the Early–Middle Miocene interval in the European region and the Middle East. All analyzed samples were dated using integrated biostratigraphy and chemostratigraphy (strontium isotope stratigraphy) to ensure maximum robustness of the stratigraphic correlations. In general, thevariability in calcareous nannofossil assemblages reflects the quality of the surficial water masses. We focused on
characteristics such as warm-water taxa ratios, diversity, dominance, and distribution of different assemblage types, allof which were subjected to multivariate statistical methods. These results were then compared with high precision εNddata. Although the distribution of calcareous nannoplankton in marginal areas is thought to be primarily related to thevariance of surface water temperatures, which correspond to climatic zones and the presence of stress factors, whenthese data are combined with high precision 143Nd/144Nd data, they can significantly contribute to refining paleogeographic reconstructions of complex marine regions.
References:
Bialik, O.M., Frank, M., Betzler, C., Zammit, R. & Waldmann, N.D. 2019. Two-step closure of the Miocene Indian Ocean Gateway to the Mediterranean. Scientific Reports, 9: 8842. https://doi.org/10.1038/s41598-019-45308-7
Popov, S.V., Rögl, F., Rozanov, A.Y., Steininger, F.F., Shcherba, I.G. & Kováč, M. 2004. Lithological-paleogeographic maps of Paratethys - 10 maps
Late Eocene to Pliocene. Courier Forschungsinstitut Senckenberg, 250: 1–46.
von Blanckenburg, F. 1999. Tracing past ocean circulation? Science, 286: 1862–1863. https://doi.org/10.1126/science.286.5446.1862b

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Ultrastructure and taxonomy of the Families Axopodorhabdaceae and Cretarhabdaceae
Richard W. Howe

Ellington Geological Services, Houston TX 77043, USA; Richard.howe@yahoo.com

https://doi.org/10.58998/jnr3238
The Families Axopodorhabdaceae and Cretarhabdaceae are two placolith heterococcolith families that originated in the
Early Jurassic and went extinct at the end of the Cretaceous. They are generally classified together in the Order Podorhabdales. However, although superficially similar, their ultrastructures are quite different (Figure 1). Both families have“conventional” placolith morphologies with an R-unit proximal shield, a V-unit distal shield, an R-unit tube cycle, anda central-area structure. However, the arrangements of the tube cycle and central-area structures are distinctly different
between the two families, suggesting that they may not be as closely related as previously thought.
Electron microscope (EM) images of typical Axopodorhabdaceae species show a steeply inclined petaloid (i.e., nonimbricate) tube cycle lining the central area. Because the tube-cycle elements are steeply inclined and non-imbricate,they are generally bright in cross-polarized light (XPL) with a characteristic “beaded” appearance. The central-areastructure grows inwards and upwards from the base of the tube cycle. Where a spine is present, it is always hollow witha distinct central cavity present the entire length of the spine. Because the central-area structure grows from the base of
the tube cycle, it is referred to here as “low”.
In EM images, typical Cretarhabdaceae species appear to have three shields, which has led to much confusion on
their taxonomic position. However, what appears to be a distal third shield is actually the tube cycle. Unlike in the
Axopodorhabdaceae, this tube cycle grows (sub)horizontally, fully or partly covering the top of the V-unit distal shield.
Although it is composed of petaloid R-units, because the tube cycle is flat lying, its vertical thickness is low, resulting in
relatively low birefringence in XPL. Because the tube cycle may fully (e.g., Cruciellipsis) or partly (e.g., Cretarhabdus)
cover the distal shield, some species have an apparently unicyclic or bicyclic appearance under XPL. Where a spine
is present, it is always solid, unlike the hollow spines of the Axopodorhabdaceae. The central-area structure is raised
because the tube cycle is also raised up to cover the distal shield and is referred to here as “high”.
With a clear understanding of the ultrastructure of the two families, it is possible to show that several species havebeen incorrectly assigned to either the Axopodorhabdaceae or the Cretarhabdaceae. It is essential to properly characterize the tube cycle, the relative height of the central area, and the nature of the spine to correctly assign taxa to eitherfamily.

INA1961

Inclined tube cycle

Hollow spine
Inclined
tube
cycle

Low central-areastructure

X
Hollow spine
D

P

Axopodorhabdus

AXOPODORHABDACEAE
Flat
tube
cycle

Flat tube cycle Solid spine(completely
covers distal
High central-areashield)structure
X

Solid spine

Distalshield

Flat
tube
cycle

Cruciellipsis

Flat tube cycle(does notcompletely
cover distal
shield)Solid spine
High central-areastructure
X

Solid spine

D

P

Retecapsa

CRETARHABDACEAE
V-unit distal shield

R-unit tube cycle

R-unit proximal shield

Central-area structure

Spine

R-unit transition between
proximal cycle and tube cycle
Figure 1. Schematic ultrastructure of the Axopodorhabdaceae and Cretarhabdaceae. D = distal side, P = proximal side, X = cross section.

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Ultrastructure and taxonomy of the Order Arkhangelskiales
Richard W. Howe

Ellington Geological Services, Houston TX 77043, USA; Richard.howe@yahoo.com

https://doi.org/10.58998/jnr3239
The Order Arkhangelskiales is a group of Cretaceous heterococcoliths that are united by a common ultrastructure. They
are muroliths with a thin and narrow R-unit proximal cycle, a tall and wide V-unit outer wall, an R-unit tube cycle, anda central-area structure (Figure 1). The key innovation that separates the Arkhangelskiales from other Cretaceous muroliths is that the outer wall is wide and grows inward of the tube cycle so that the tube-cycle elements grow upwards
through the outer wall, which is not seen in any other group. This divides the outer wall into inner and outer sections, andresults in a superficially complex ultrastructure. Another key feature of taxa in the order is the presence of lateral ridges
that extend outward from the outer wall, resulting in a tiered appearance in lateral view that superficially resembles
placolith morphology. It is unclear whether all taxa within this order have tiers, although most do. In most species, theinner and outer sections of the outer wall meet distally at a marginal suture. A central-area structure is present inside theinner section of the outer wall, usually with a perforate plate or axial cross, and it sometimes has accessory bars.
There are two families within the order, the Arkhangelskiellaceae and Kamptneriaceae. These two families havesuperficially different ultrastructures but clearly have a common origin because they share the key characteristics of theouter wall growing inward of the tube cycle and tiers being present on the outer wall. The evolutionary origin of theorder is unclear. The first unambiguous member of the order is Broinsonia in the Arkhangelskiellaceae, which appearedin the early Albian. In Broinsonia and the closely related Aspidolithus, the tube cycle grows up through the outer walland grows laterally on top of the distal surface of the outer wall where it shows a complex suture pattern between adjacent elements. Outside of the marginal suture, a narrow outer section of the outer wall is present on the distal surface. A
single cycle of subcircular depressions is present on the distal surface of the tube cycle in many species of Broinsonia
and Aspidolithus. Arkhangelskiella evolved from Aspidolithus in the Santonian–Campanian with the tube cycle growing laterally on the distal surface to cover the outer wall mostly or completely, and the complex tube-cycle sutures of
Aspidolithus became simple radial sutures in Arkhangelskiella.
In the Albian–Cenomanian, the Kamptneriaceae evolved from Broinsonia through loss of the distal portion of the
tube cycle, leaving the distal surface of the inner section of the outer wall exposed. The tube cycle in Gartnerago is muchnarrower than in Broinsonia, and on the distal surface it is completely covered by the outer wall, making it visible in
the light microscope but not in the electron microscope. The marginal suture marks, where the inner and outer sectionsof the outer wall meet on the distal surface, completely cover the tube cycle. In Kamptnerius, the distal part of the outer
section of the outer wall extends laterally to form an asymmetrical flange. The inner section of the outer wall is muchwider than in Gartnerago, and the central plate is correspondingly reduced in width. The inner section of the outer wall
may be perforate.
Correctly characterizing species in the Arkhangelskiales requires careful observation of the tube cycle, both the inner and outer sections of the outer wall, the position of the marginal suture, and the nature of the central-area structure.

INA19Complex Outer section
Inner section
Tiers of outer wallsutures of outer wall
Proximalon tube
cycle
cycle

D
Marginal
SutureDepressions

X

Inner sectionof outer wall

P

Tiers

Radial sutures
on tube cycle
Proximalcycle

Inner sectionof outer wall

Tiers

P

D

Outer sectionof outer wall

Broinsonia

63

X

Outer sectionof outer wall

Inner sectionof outer wall

Arkhangelskiella

Tiers

ARKHANGELSKIELLACEAE
Outer sectionof outer wallD
Marginal
Suture
X
Tiers

Tiers

Inner sectionof outer wall
Hidden tube
cycle

Gartnerago
V-unit outer wall,outer section
V-unit outer wall,inner section

Proximalcycle

FlangeOuter sectionof outer wallP
Marginal
SutureD

Outer sectionof outer wall

KAMPTNERIACEAE

Inner sectionof outer wall

Hidden tube
cycle

Kamptnerius

R-unit proximal cycle

P
X
Tiers

Central-area structure

R-unit tube cycle
R-unit transition between
proximal cycle and tube cycle

Figure 1. Schematic ultrastructure of the Order Arkhangelskiales. D = distal side, P = proximal side, X = cross section.

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Ultrastructure and taxonomy of the Order Watznaueriales
Richard W. Howe

Ellington Geological Services, Houston TX 77043, USA; Richard.howe@yahoo.com

https://doi.org/10.58998/jnr3240
The Order Watznaueriales is a group of Early Jurassic to Recent placolith heterococcoliths that are united by a common ultrastructure. Either two or three shields are present, the lower two shields having R-unit elements, and the third
shield, when present, having V-unit elements (Figure 1). An R-unit tube cycle is usually present, as well as a central-areastructure that can include plates, axial crosses, transverse bars, or may be open. This ultrastructure is quite different fromother placolith families, which usually have R-unit proximal shields and V-unit distal shields. Three families are placed
within the Order Watznaueriales: Bussoniaceae, Ellipsagelosphaeraceae, and Noelaerhabdaceae. The Noelaerhabdaceae
have generally been considered to have evolved from the Family Prinsiaceae (Order Isochrysidales). However, the ultrastructure of the Noelaerhabdaceae has much more in common with the Ellipsagelosphaeraceae.
The Watznaueriales appeared during the Early Jurassic with the evolution of the genus Mazaganella (Family Bussoniaceae) from the ancestral murolith genus Crucirhabdus. The key innovations in Mazaganella were a doubling of
the R-unit proximal cycle and development of a lateral extension of both the proximal and distal cycles, resulting in aplacolith morphology with two proximal shields and a raised distal shield. Bussonius then evolved from Mazaganella
with the inception of imbrication in the shields. In a separate branch of the family, Triscutum evolved from Mazaganella
through the development of a high non-imbricate distal shield.
The Family Ellipsagelosphaeraceae evolved with the appearance of Lotharingius in which the raised V-unit distal
shield of Bussonius was reduced in height and width until it was close to level with the distal surface of the upper of
the two proximal shields. This relict V-unit cycle is here referred to as the crown cycle. The upper of the two R-unit
proximal shields in Bussonius became the distal shield in Lotharingius. The R-unit distal shield in Lotharingius and all
subsequent descendants has no homology to the V-unit distal shield of the Bussoniaceae. The basic ultrastructure of Lotharingius continued through the Mesozoic with the appearance of Ellipsagelosphaera, Watznaueria, Cyclagelosphaera,and Ansulasphaera, all of which have a crown cycle and R-unit proximal and distal shields. Only Cyclagelosphaera
survived the K/Pg boundary mass extinction, and it is still extant as Tergestiella.
In the Ypresian, Cyclagelosphaera gave rise to Cyclicargolithus in the Family Noelaerhabdaceae through the complete loss of the V-unit crown cycle. The Ellipsagelosphaeraceae and Noelaerhabdaceae have in common two R-unitshields, an ultrastructure not seen in any other placolith group, which is considered strong evidence of a very close relationship between the two families. The basic ultrastructure of Cyclicargolithus has been conserved from the Ypresianthrough Recent in Reticulofenestra, Dictyococcites, Cribrocentrum, Crenalithus, and Pseudoemiliania, and in the extant
Gephyrocapsa.

INA19V-unit
outer
wall

65

R-unit
tube
cycle

X

SingleR-unitproximalcycle

DoubleR-unitproximalshieldV-unitdistalshieldX

Crucirhabdus

Mazaganella

Triscutum

V-unit Crown cycle

Bussonius
Bussonius

BUSSONIACEAE

V-unitCrown
cycle

R-unitdistalshieldX

Lotharingius

Lotharingius
Watznaueria
Ellipsagelosphaera
Cyclagelosphaera

ELLIPSAGELOSPHAERACEAE

R-unitdistalshieldCyclicargolithus

R-unitproximalshieldR-unit
tube
cycle

X
R-unitproximal Cyclicargolithus
shieldReticulofenestra
Gephyrocapsa

NOELAERHABDACEAE
V-unit distal shield orcrown cycle
R-unit proximal or
distal shield
R-unit tube cycle

R-unit transition between
proximal cycle and tube cycle
Spine
Central-area structure

Figure 1. Schematic distal side ultrastructure of the Order Watznaueriales. X = cross section.

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Nannofossil abundance and diversity changes – a reaction
to changing paleoenvironments in the late Tithonian of theFlemish Pass Basin, offshore Newfoundland
Jason Jeremiah

Viridien, Crompton Way, Manor Royal Estate, Crawley RH10 9QN, UK; jason.jeremiah@cgg.com

Stephen Schwartz

Equinor Canada Ltd., St. John’s, NL A1C 6J5, Canada; Memorial University of Newfoundland, Department of Earth Sciences, St. John’s, NL A1B
3X5, Canada; stesch@equinor.com

https://doi.org/10.58998/jnr3241
The Flemish Pass is a Mesozoic extensional basin located 500 km offshore of Newfoundland that contains multiple
oil discovery areas operated by Equinor Canada Ltd. Reservoirs are of late Tithonian through early Berriasian age andare represented by a series of incised valleys that consist of fluvio-deltaic sandstones and intervening marine shales.
Nannofossil analyses from cores and cuttings have been conducted to supplement sedimentological core observations,interpretations, and uncertainties. Here, we present an integrated sedimentological and nannofossil review from a corethat details a unique set of lithofacies and nannofossil variations that demonstrate paleoenvironmental changes and theflooding of a late Tithonian delta system.
Three facies associations are interpreted across the Bay de Verde F-67Z cored interval between 3043 and 3053 m.
The basal facies association 1 (FA1) is represented by rhythmic, finely laminated, dark gray organic mudstone, lightgray siltstone, red-brown organic mudstone, and calcareous laminae, which lack bioturbation. It is gradationally overlain
by facies association 2 (FA2) with variably crypto-bioturbated lithofacies, consisting of black organic mudstone, lightgray calcareous to silty mudstone, and very fine-grained sandstone laminae. The youngest sediments are dominated byfacies association 3 (FA3), which is predominantly comprised of calcareous mudstone and marl beds that are intensely
bioturbated and contain a diverse ichnofabric.
The nannofossil assemblages are characteristic of the North Atlantic Tethyan Province with Acadialithus valentinei,
Nannoconus magnadiscus, and Polycostella senaria prevalent. FA1 yields high-abundance, opportunistic nannofossil
bloom assemblages that can be attributed to upwelling conditions and are located at the base of the prodelta slope. The
calcareous laminae were found to yield prolific coccospheres. Benthic foraminiferal assemblages are absent, but there
are isolated radiolarian influxes. FA2 contains increased nannoflora diversity. Anoxic through hypoxic bottom waters
are prevalent with continued deposition of black, organic mudstone, but agglutinated foraminifera are present that indicate increased oxygenation in the substrate. FA3 yields highly bioturbated marls, which yield a diverse calcareous
benthic foraminiferal assemblage in association with a high abundance and diversity of nannoflora that is typical of afully oxygenated marine shelf.

INA1967

Estimating the coccolithophore ratio of particulate inorganiccarbon to particulate organic carbon from the geometry ofliving cells
Xiaobo Jin

Tongji University, State Key Laboratory of Marine Geology, Shanghai, China, 386jinxiaobo@tongji.edu.cn

Chuanlian Liu

Tongji University, State Key Laboratory of Marine Geology, Shanghai, China, liucl@tongji.edu.cn

https://doi.org/10.58998/jnr3242
Marine biological calcification and photosynthesis can produce particulate inorganic and organic carbon (PIC and POC),
which have opposite effects on seawater CO2. Coccolithophores are marine unicellular algae that both photosynthesize
and calcify, and their production of PIC and POC can influence the water column rain ratio as a dominant driver for
Earth’s carbon cycle. Thus, changes in ancient coccolithophore PIC:POC ratios can be important for paleoceanographic
and paleoclimatic studies of carbon cycle modeling. However, ancient coccolithophore PIC:POC ratios are poorly constrained because of the limited occurrences of intact coccospheres in deep ocean sediments. Instead, detached coccoliths,
the remnants of fossilized coccolithophores, are commonly found. Here, we carry out the biometric analysis of coccospheres and coccoliths from the living cells of Emiliania huxleyi and Gephyrocapsa oceanica in the South China Sea andconfirm a significant correlation between the PIC:POC ratio and the lateral coccolith aspect ratio (ARL), which is here
defined as the ratio of mean coccolith thickness with respect to coccolith length. A linear regression, PIC:POC = 15.023
× ARL - 0.083 (R2 = 0.59, n = 121), for the reconstruction of ancient Noelaerhabdaceae coccolithophore PIC:POC ratio
is based on individual coccoliths in marine sediments. Based on this equation, we can reconstruct ancient Noelaerhabdaceae coccolithophore PIC:POC ratios for the past 14 million years (Ma) using published coccolith data, which reveal
a long-term decrease in PIC:POC ratios from 7 to 4 Ma. We suggest that such a change in coccolithophore physiology
may be induced by a simultaneous long-term decline in the seawater calcium concentration.

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INA19

The search for fossil siliceous haptophytes
Richard W. Jordan

Yamagata University, Faculty of Science, 1-4-12 Kojirakawa-machi, Yamagata 990-8560, Japan; sh081@kdw.kj.yamagata-u.ac.jp

Kenta Abe

Senzaki Co., Ltd., 3-5-2 Izumihoncho, Komae, Tokyo 201-0003, Japan; 104b0154@gmail.com

Luca Pellegrino, Francesca Lozar

Università degli Studi di Torino, Departimento di Scienze della Terra, 10125 Torino, Italia; lu.pellegrino@unito.it; francesca.lozar@unito.it

https://doi.org/10.58998/jnr3243
Almost twenty years ago, an enigmatic marine nannoplankton, Hyalolithus neolepis, was determined to be a haptophyte
covered in siliceous scales. Subsequent research provided convincing evidence that another silica-scaled nannoplankton,
Petasaria heterolepis, was also likely to be a haptophyte. Preliminary studies of the fossil record have recently revealed
two species of Hyalolithus, H. tumescens (middle Eocene) and H. didymus (Late Miocene), and have proposed that twosiliceous microfossil genera, Macrora (middle Eocene–Late Miocene) and Clathropyxidella (middle Eocene), could also
be related. Given the large gaps in geological time between the three Hyalolithus spp., as well as the overlap between
the three Macrora spp., we decided to make a sample request using the abundance charts and illustrations in the DeepSea Drilling Project (DSDP), Ocean Drilling Program (ODP), and Integrated Ocean Drilling Program and International
Ocean Discovery Program (collectively known as IODP) literature as a guide. As a consequence, we obtained 167
samples from various geographical regions, ranging from middle Eocene to Late Miocene/Pliocene in age, and preparedthem for light microscope and scanning electron microscope examination. Outcrop samples were also reinvestigated,notably from Barbados (Caribbean), California (USA), Marmorito (Italy), Porcuna (Spain), and Israel. Our observations confirmed the presence of three species in middle Eocene samples: (1) Macrora barbadensis from DSDP Legs 4(Venezuela Basin), 21 (Lord Howe Rise), and 95 (New Jersey Transect), and from Barbados; (2) Macrora najae from
Barbados; and (3) Clathropyxidella similis from DSDP Legs 4 and 21 (Venezuela Basin and Lord Howe Rise). Upper
Oligocene samples from ODP Leg 119 (Kerguelen Plateau), Lower Miocene samples from Marmorito (Italy), and Upper Miocene samples from Porcuna (Spain) contained Macrora stella.

INA1969

Oligocene to Recent North Atlantic biostratigraphy andcalcareous nannofossil assemblages (IODP Expedition 395)
Boris Theophanes Karatsolis

Vrije Universiteit Brussel, Archaeology Environmental Changes & Geo-Chemistry (AMGC), Brussels, Belgium; Department of Earth Sciences,
Uppsala University, Uppsala, Sweden; boris.karatsolis@vub.be

Tom Dunkley-Jones

University of Birmingham, School of Geography, Earth and Environmental Sciences, Birmingham, UK; t.dunkleyjones@bham.ac.uk

Paul N. Pearson

University College London, Department of Earth Sciences, London, UK; p.pearson@ucl.ac.uk

Takuma Suzuki

Centre for Advanced Marine Core Research, Kochi, Japan; zaku142@gmail.com

Ross Parnell-Turner

Scripps Institution of Oceanography, UC San Diego, La Jolla, CA, USA; rparnellturner@ucsd.edu

Anne Briais

Institut Universitaire Européen de la Mer, Plouzané, France; anne.briais@univ-brest.fr

Leah LeVay

Texas A&M University, International Ocean Discovery Program, College Station, TX, USA; levay@iodp.tamu.edu

Expedition 395/395C Scientists
https://doi.org/10.58998/jnr3244
Low-latitude biozonation schemes of calcareous nannoplankton and planktonic foraminifera are hard to implement inhigher latitudes due to the absence of warm-water species in temperate to cold water masses. Continuous records withwell-preserved fossils are therefore crucial to build robust biostratigraphic schemes and explore calcareous nannofossil
assemblage changes within the Cenozoic. International Ocean Discovery Program (IODP) Expeditions 384, 395C, and395 drilled six sites in the North Atlantic at a latitude of ~60°N, recovering sedimentary sequences from the Irminger
and Iceland Basins that date back to the early Oligocene. Five Expedition 395 sites (U1554, U1555, U1562, U1563, andU1564) are located on a transect to the east of the North Atlantic mid-ocean ridge, and one site (U1602) is located to thewest of the ridge. Integrated calcareous nannofossil, planktonic foraminiferal, and bolboform occurrences allowed for arobust reconstruction of biohorizons that are well correlated across sites.
Calcareous nannofossils are present to abundant in most samples, and their preservation is moderate to good, whereasintervals of very good preservation also occurred, primarily for the Pliocene and Pleistocene. Species that belong to thegenera Reticulofenestra and Coccolithus are the most dominant across all sites and geological time intervals, whereas
Gephyrocapsa species commonly dominate the Upper Pleistocene assemblages. Higher abundances of species affiliatedwith warmer waters, such as Sphenolithus sp., were observed in samples dated to the Early and Late Miocene, both tothe east and west of the Mid-Atlantic Ridge.

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Calcareous nannofossils from the Poggio le Guaine core
(Umbria-Marche Basin, central Italy): Biostratigraphy anddiscussion of Aptian–Albian bioevents
Fábio Lamm

Universidade Federal do Rio de Janeiro, Instituto de Geociências, Departamento de Geologia, Programa de Pós-Graduação em Geologia; Cidade
Universitária, Rio de Janeiro, RJ, Brazil; Petrobras, Research Centre (CENPES), 950, Ilha do Fundão, Cidade Universitária, Rio de Janeiro, RJ,
21941-915, Brazil; fabio.lamm@petrobras.com.br

Francisco Henrique de Oliveira Lima

Petrobras, Research Centre (CENPES), 950, Ilha do Fundão, Cidade Universitária, Rio de Janeiro, RJ, 21941-915, Brazil;
henriquel@petrobras.com.br

Cleber Fernandes Alves

Universidade Federal do Rio de Janeiro, Instituto de Geociências, Departamento de Geologia, Laboratório de Palinofácies e Fácies Orgânica
(LAFO), Cidade Universitária, Rio de Janeiro, RJ, Brazil; alvescf@gmail.com

Ismar de Souza Carvalho

Universidade Federal do Rio de Janeiro, Instituto de Geociências, Departamento de Geologia, Cidade Universitária, Rio de Janeiro, RJ, Brazil;
Universidade de Coimbra, Centro de Geociências, Rua Sílvio Lima, 3030-790, Coimbra, Portugal; ismar@geologia.ufjr.br

https://doi.org/10.58998/jnr3245
Calcareous nannofossil biostratigraphy of the Aptian–Albian interval has been developed and applied in recent decades.
However, the shortage of complete and continuous outcropping marine sections, or even marine subsurface sections,has presented a significant challenge for stratigraphic studies of this interval. Taxonomic ambiguities, diachroneity, andreworking are additional challenges for calcareous nannofossil biostratigraphic studies of this interval. In contrast, thePoggio le Guaine (PLG) section of the Umbria-Marche Basin (central Italy) stands out by presenting a complete pelagic
to hemipelagic marine sedimentary succession of the Aptian–Albian interval.
In this study, we (1) provide a detailed calcareous nannofossil biostratigraphy, (2) calibrate the results with previously published work, and (3) discuss some important bioevents of the Aptian–Albian interval that we identified in the
PLG core. The following biozones of the calcareous nannofossil reference zonation for the Aptian–Albian interval wererecognized: Chiastozygus litterarius Zone (NC6), Rhagodiscus angustus Zone (NC7), Prediscosphaera columnata Zone
(NC8* and NC8), Axopodorhabdus albianus Zone (NC9), and Eiffellithus turriseiffelii Zone (NC10). The PLG coreencompasses the chronostratigraphic interval from the Barremian/Aptian through the Albian/Cenomanian boundaries.
Finally, we also recognized some important calcareous nannofossil bioevents within this interval: the first occurrence(FO) of Hayesites irregularis, FO of Hayesites albiensis, last occurrence (LO) of Conusphaera rothii, LO of Micrantholithus hoschulzii/Micrantholithus obtusus, FO of Rhagodiscus achlyostaurion, FO of Prediscosphaera columnata, FO
of Tranolithus orionatus, and LO of Assipetra spp.

INA19

Ceratolithaceae
Caribbean Sea

biostratigraphy

71

of

ODP

Hole

999A,

Carlos Lancis

University of Alicante, Department of Earth and Environmental Sciences, 03080 San Vicente del Raspeig, Alicante, Spain; carlos.lancis@ua.es

José Enrique Tent-Manclús

University of Alicante, Department of Earth and Environmental Sciences, 03080 San Vicente del Raspeig, Alicante, Spain; je.tent@ua.es

José-Abel Flores

Universidad de Salamanca, Department of Geology, 37008, Salamanca, Spain; flores@usal.es

https://doi.org/10.58998/jnr3246
Ocean Drilling Program (ODP) Hole 999A was drilling during Leg 165 and is located on a promontory nearly 1000m above the relatively flat Colombian Plain (Caribbean Sea) at 2828 m water depth. A total of 102 smear slides werestudied from this hole between 224.58 meters composite depth below seafloor (mcd) and 180.59 mcd. To determine
the fine details of the nannofossil structures, 46 samples were prepared for scanning electron microscopy (SEM) using
a technique of centrifugation/filtration. The focus of our work is from the lowest occurrence of Amaurolithus primus at
211.12 mcd in sample 999B-24X-1, 90 cm, to the highest occurrence of Ceratolithus atlanticus at 158.22 mcd in sample
999B-17H-6, 90 cm.
Amaurolithus delicatus, which evolved from A. primus, first appears at 209.06 mcd, followed by Nicklithus amplificus, which evolved from Orthorhabdus rugosus and appears at about 204.02 mcd. At 189.41 mcd, A. primus is no longer
present, and at 181.93 mcd, N. amplificus is also absent. In the latest Messinian, a new ceratolith branch evolved from O.
rugosus. The first species present is Ceratolithus finifer at 165.99 mcd. This sample also contains A. delicatus, the only
species left from the previous ceratolith branch. Above the first appearance of C. finifer, the following species rapidly
appear: C. acutus (165.56 mcd), C.? atlanticus (161.76 mcd), C. larrymayeri and C.? tricorniculatus (both at 160.91mcd), C. armatus (160.50 mcd), and C. cristatus (159.65 mcd). The highest occurrences of C. finifer and C.? atlanticus
are at 158.22 mcd. Ceratolithus? atlanticus is abundant, and it has a short range between 5.322 and 5.173 Ma (Lancis etal., 2024). Ceratolithus? tricorniculatus is scarce in the studied samples.
References:
Lancis, C., Tent-Manclús, J.E. & Flores, J.-A. 2024. Origin and evolution of the Neogene calcareous nannofossil Ceratolithus. Marine Micropaleontology, 186: 102310. https://doi.org/10.1016/j.marmicro.2023.102310

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Ceratolithaceae biostratigraphy of ODP Site 1237, equatorial
Pacific
Carlos Lancis

University of Alicante, Department of Earth and Environmental Sciences, 03080 San Vicente del Raspeig, Alicante, Spain; carlos.lancis@ua.es

José Enrique Tent-Manclús

University of Alicante, Department of Earth and Environmental Sciences, 03080 San Vicente del Raspeig, Alicante, Spain; je.tent@ua.es

José-Abel Flores

Universidad de Salamanca, Department of Geology, 37008, Salamanca, Spain; flores@usal.es

https://doi.org/10.58998/jnr3247
Site 1237 was drilled during Ocean Drilling Program (ODP) Leg 202 in the equatorial Pacific at a water depth of 3212 m
on the easternmost flank of the Nazca Ridge, approximately 140 km off the coast of Peru. Four boreholes were drilled:
Holes 1237A, 1237B, 1237C, and 1237D. Forty-two smear slides were studied from Hole 1237B between 179.67 meters composite depth below seafloor (mcd) and 113.53 mcd. To determine the fine details of the nannofossil structures,
63 samples from Holes 1237B, 1237C, and 1237D were prepared for scanning electron microscopy (SEM) using atechnique of centrifugation/filtration. The focus of our work is from the lowest occurrence of Amaurolithus primus at
149.86 mcd in sample 1237B-15H-6, 75 cm, which evolved from Orthorhabdus rugosus, to the highest occurrence of
Amaurolithus delicatus at 54.49 mcd (sample 1237B-6H-4, 75 cm).
Amaurolithus delicatus, which evolved from A. primus, first appears at 143.81 mcd, followed by Nicklithus amplificus, which also evolved from O. rugosus and first occurs at about 135.22 mcd. At 124.84 mcd, A. primus is no longer
present, and at 115.04 mcd, N. amplificus is also absent. In the latest Messinian, a new ceratolith branch evolved fromO. rugosus. The first species to evolve is Ceratolithus finifer, which we found at 94.01 mcd. This sample also contains
A. delicatus, the only species left from the previous ceratolith branch. After the appearance of C. finifer, the following
species rapidly appear: C. acutus (90.67 mcd), C. armatus (87.71 mcd), C.? tricorniculatus (86.45 mcd), C. larrymayeri(86.34 mcd), C.? atlanticus (84.96 mcd), and C. cristatus (83.54 mcd). The highest occurrences of C. armatus (81.12mcd), C. acutus (80.01 mcd), and C. larrymayeri and C.? tricorniculatus (both at 77.30 mcd) are found in close succession, whereas A. delicatus is present to 54.49 mcd. Ceratolithus cristatus is the only ceratolith present above 54.49 mcd.
Ceratolithus? atlanticus is scarce in studied samples.

INA1973

Structural developments within the Family Ceratolithaceae
Carlos Lancis

University of Alicante, Department of Earth and Environmental Sciences, 03080 San Vicente del Raspeig, Alicante, Spain; carlos.lancis@ua.es

José Enrique Tent-Manclús

University of Alicante, Department of Earth and Environmental Sciences, 03080 San Vicente del Raspeig, Alicante, Spain; je.tent@ua.es

José-Abel Flores

Universidad de Salamanca, Department of Geology, 37008, Salamanca, Spain; flores@usal.es

https://doi.org/10.58998/jnr3248
The horseshoe-shaped nannoliths, which are commonly known as ceratoliths, have unique calcite crystals that may or
may not show birefringence, depending on how they settle into a stable position during smear slide preparation. Raffiet al. (1998) pointed out that the horseshoe structure evolved three different times from Orthorhabdus rugosus, whichusually does not show any birefringence because in its most stable position it has a middle blade oriented straight up.
The c-axis is perpendicular to the length of the nannolith and parallel to this median blade, and at both sides there are
two blades in about the same plane (Lancis et al., 2022). This rod-shaped and bladed nannolith has two pointed ends.
With the sharper end pointing away from the observer and the median blade face up, the blade to the right is the dextral
blade and the one to the left the sinistral blade.
The first two horseshoe developments do not show any birefringence because in their most stable layouts the c-axis
points upward and basically coincides with the median blade. Both ceratolith horseshoe structures were produced by thesinistral blade becoming the sinistral arm and the median and dextral blade becoming the dextral arm. The Amaurolithus
branch started with A. primus, which then evolved into A. delicatus. Amaurolithus primus became extinct in the lateMessinian, whereas A. delicatus continued into the Pliocene. The second branch consists of only one species, the short
lived Nicklithus amplificus.
From the end of the Messinian to the early Pliocene, a new genus, Ceratolithus, evolved from O. rugosus. The
Ceratolithus horseshoe structure is formed by the O. rugosus sinistral blade producing the sinistral arm, the dextral arm
is formed from the median blade, and the dextral blade becomes reduced to a keel. The genus Ceratolithus shows birefringence because the median blade of O. rugosus rotated to the right during the evolution of C. finifer to be parallel tothe most stable layout, thus showing birefringence when observed with cross-polarized light (Lancis et al., 2024). Older
specimens of C. finifer commonly have low birefringence, whereas younger specimens have high birefringence. The
more recent C. finifer form evolved into three branches: (1) C. acutus, C. armatus, C. cristatus, and C. larrymayeri, (2)C.? atlanticus, and (3) C.? tricorniculatus.
References:
Lancis, C., Tent-Manclús, J.E. & Flores, J.-A. 2022. Origin and evolutionary trends of the Neogene genera Amaurolithus and Nicklithus (calcareous
nannofossils). Marine Micropaleontology, 175: 102156. https://doi.org/10.1016/j.marmicro.2022.102156
Lancis, C., Tent-Manclús, J.E. & Flores, J.-A. 2024. Origin and evolution of the Neogene calcareous nannofossil Ceratolithus. Marine Micropaleontology, 186: 102310. https://doi.org/10.1016/j.marmicro.2023.102310
Raffi, I., Backman, J. & Rio, D. 1998. Evolutionary trends of tropical calcareous nannofossils in the late Neogene. Marine Micropaleontology, 35(1):17–41. https://doi.org/10.1016/S0377-8398(98)00014-0

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A YOLO model for coccolithophore identification using
images from ocean water samples
Guillaume Lassus

Aix-Marseille University, CNRS, IRD, INRAE, CEREGE, 13090 Aix-en-Provence, France; ZORTH, Technopole de l’Arbois, 13090 Aix-enProvence, France; lassus@cerege.fr

Luc Beaufort

Aix-Marseille University, CNRS, IRD, INRAE, CEREGE, 13090 Aix-en-Provence, France; beaufort@cerege.fr

David Mendels

ZORTH, Technopole de l’Arbois, 13090 Aix-en-Provence, France; david@zorth.net

https://doi.org/10.58998/jnr3249
Coccolithophores represent one of the major phytoplankton groups and have been extensively studied by scientists.
Despite their small size (2–20 µm diameter), the use of polarized light facilitates their microscopic observation, thanks
to the birefringent properties of their calcite composition. In 2002, the neural network SYRACO (SYstème de Reconnaissance Automatique de COccolithophores), developed since 1994 by Luc Beaufort and Denis Dollfus, was used tocount and identify coccolithophores from different types of samples from deep-sea sediments to ocean water samples.
Recent developments in artificial intelligence allow fast segmentation and classification that are fully adapted to oceanic
samples. YOLO (« You Only Live Once »), a deep learning algorithm developed since 2016, is a rapid method (several
minutes or hours) to train models for the detection of specific objects on images. Besides its precision and versatility,
one of YOLO’s most prominent features is its ability to instantly detect and identify objects after scanning an image
once. It can also be used for image segmentation, and it is frequently updated with version 8 released in January 2023.
In order to train a model, a dataset comprised of artificially generated images was assembled by gathering a large
number of segmented images of coccolithophores of various species and shapes. These images were then randomly
pasted onto background images. Two training courses were tested: first, a single class model trained with 1950 instancesof various species of coccolithophores that were distributed on approximately 150 images, and second, a multi-species
model trained to identify 10 classes of coccolithophores, each containing 200 instances. We also created a third dataset
by combining 320 images from water samples collected in the Caribbean Sea and eastern Pacific. Several models weregenerated with varying training parameters (image size, base model size, etc.). Each model was then tested by runninga detection on the third dataset to measure and compare their efficiency (precision, recall, and F1-Score), thus allowing an assessment of the best training parameters. The best neural network was then applied to coccolithophores fromsamples collected in the southern tropical Pacific in a transect going from the Marquesas Islands to Chile during thecruise BIOSOPE in 2005. The results were compared with published SYRACO coccosphere counts and unpublishedhuman counts. The quality of the YOLOv8 model will be evaluated through this comparison.

INA1975

Nannofossil biostratigraphy in industry; female pioneers innannopaleontology and a story of life on the rigs
Tamsin Lawrence

PetroStrat Ltd., Parc Caer Seion, Conwy, LL32 8RE, UK; tamsin.lawrence@petrostrat.com

Emma Sheldon

Geological Survey of Denmark and Greenland, Department of Geo-energy and Storage, DK 1350, Copenhagen K, Denmark; es@geus.dk

https://doi.org/10.58998/jnr3250
The applied biostratigraphy community would like to pay tribute to contributions made to the advancement of nannofossil biostratigraphy in an offshore setting by Donata Zucchi, whose life was tragically cut short by her untimely death in2021.
A large proportion of work on offshore oil and gas installations can be characterized by hard physical labor in occasionally dangerous, dirty conditions and uncomfortable weather conditions from the extremes of the North Sea to theheat, humidity, and hurricane season in the Gulf of Mexico. The offshore industry has been traditionally male dominatedand estimates from 2021 indicate that only around 3–5% of offshore workers globally are female. From the late 1970s,
when women infrequently began to work at wellsites, to the present day, the majority of female offshore workers havebeen employed in the catering, cleaning, medical, and administrative divisions. In the North Sea by the mid-1980s,
women occasionally began to work offshore in other positions, for example, as biostratigraphy technicians. By the mid1990s, biostratigrapher, wellsite geologist, mud-logger, and data engineer roles began to be filled by women. Today,
positions traditionally filled by men, such as driller, crane operator, and roughneck, are now beginning to be occupied
by women.
Biostratigraphy has been used in real-time offshore hydrocarbon exploration for approximately five decades. Initially, microfossil (mainly foraminifera) biostratigraphy was utilized, paving the way for expansion into the use of
nannofossil biostratigraphy, which was routinely used in North Sea exploration and the development of Cretaceousand Paleogene chalk oil and gas fields. Today, applied, real-time nannofossil biostratigraphy has global applications
and covers the stratigraphic column from the Jurassic to the Recent. The use of biostratigraphy on offshore oil and gas
installations is one of the pioneering jobs that introduced women into the offshore world on an equal footing, a worldthat has changed significantly since the 1970s and 1980s!
Donata Zucchi embraced the changes and challenges of offshore life with enthusiasm, good humor, and intelligencein a career spanning 25 years “in the field”, which often took her to extremely challenging environments, including West
Africa, Mexico, and the northernmost extremes of the North Sea. We are extremely grateful to her for her pioneering
efforts.

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The relationship between the carbonate counter pump andseawater CO2 in the Middle Miocene
Chuanlian Liu

Tongji University, State Key Laboratory of Marine Geology, Shanghai, China, 200092; liucl@tongji.edu.cn

Lishun Sun

Tongji University, State Key Laboratory of Marine Geology, Shanghai, China, 200092; 2131622@tongji.edu.cn

https://doi.org/10.58998/jnr3251
To understand the relationship between the carbonate counter pump and seawater CO2 in the Middle Miocene between
15 and 12 Ma, samples from International Ocean Discovery Program (IODP) Site U1505 in the South China Sea wereanalyzed for calcareous nannofossils and organic geochemistry. These included statistical analysis of the absolute abundance of calcareous nannofossils, morphological parameter measurements of Noelaerhabdaceae, alkenone and glycerol
dialkyl glycerol tetraether (GDGT) lipid content, and alkenone stable carbon isotope composition. The conclusions are
as follows:(1) The length, thickness, and mass of Noelaerhabdaceae, Helicosphaera spp., and Coccolithus pelagicus show relatively similar variation trends. There is a significant correlation between the length and thickness of Noelaerhabdaceae
coccoliths. The calcification index calculated by morphological parameters shows that the calcification of coccoliths
experienced three peaks starting from 15.2 Ma that reached a maximum value at the end of the Middle Miocene Climate
Transition (MMCT).
(2) The stable carbon isotope composition of alkenones in our samples and the calculated fraction value εp of coccolith photosynthesis decreased significantly during the MMCT. These two values are generally greater before the
MMCT than after the MMCT, which is the same trend found in benthic foraminiferal oxygen isotopes and global sea
level change. The pCO2 reconstruction using alkenones ranges from 429 to 598 ppm between 15 and 12 Ma. Overall, thepCO2 values fluctuated but also showed a decrease of about 120 ppm across the MMCT.
(3) The relationship between calcification of coccolithophores and seawater CO2 was inconsistent before and after
the MMCT. Between 15 and 13.9 Ma, coccolith calcification changes correlate with CO2 values, whereas from 13.9 to
12 Ma, coccolith calcification changes are inversely related to CO2 values, suggesting that CO2 is not the main driver ofcoccolithophore calcification. On the other hand, the mass accumulation rate of coccoliths is an indicator of the strengthof the coccolith carbonate pump, and the deposition of coccoliths can affect regional seawater CO2 values. Calcification
and abundance of Noelaerhabdaceae and benthic foraminiferal carbon isotopes change synchronously. Coccolithophore
blooms correspond to high values in benthic foraminiferal carbon isotopes, when the marine surface biological pump
was weak. This may indicate that there was competition for ecological niches between coccolithophores and diatoms orother algae.

INA1977

A decreased carbonate pump during the Oligocene–Miocenetransition: Regulating the oceanic buffering capacity
Ruigang Ma

Tongji University, State Key Laboratory of Marine Geology, Shanghai, China; maruigang@tongji.edu.cn

Chuanlian Liu

Tongji University, State Key Laboratory of Marine Geology, Shanghai, China; liucl@tongji.edu.cn

https://doi.org/10.58998/jnr3252
The ocean carbonate pump plays a crucial role in the buffering effect by regulating the ocean total alkalinity (TA) anddissolved inorganic carbon (DIC). Recent studies suggest that through the Cenozoic the TA and DIC inventory remained
relatively constant despite significant changes in continental weathering and pCO2 variations. Nevertheless, this conclusion is under debate because biogenic calcification (e.g., coccoliths) may have controlled the carbonate precipitation
more than the seawater saturation state. During the late Oligocene to the Early Miocene, a decline in pCO2 is thought
to be responsible for Antarctic glaciation, possibly through a threshold effect of ~400 ppm, a level we are approaching
today. The mechanism(s) that caused this long-term decline in pCO2 during this period remain(s) an open topic in which
fluctuations in the carbonate pump are rarely discussed.
Coccolithophores contribute as much as 90% of the carbonate production and over half of the carbonate sedimentation in the modern ocean. We reconstructed the changes in volume and flux of pelagic carbonate, specifically using Noelaerhabdaceae coccoliths. Our investigation spanned the transition from the Paleogene to the Neogene (~24–20.5 Ma),
using marine sediment samples retrieved from International Ocean Discovery Program (IODP) Sites U1501 and U1505
located in the western tropical Pacific Ocean. A circular polarized light microscope was used to measure the thickness/volume of the calcite crystals. Our results show that coccolith thickness or ks (= volume/length3) decreased from ~0.09
during the late Oligocene to ~0.06 in the Early Miocene. The ks value is positively correlated with the bulk sedimentcarbonate content (p < 0.01, R2 = 0.5). We also found that the fine fraction (<10 μm) carbonate stable carbon and oxygenisotopes indicate that there was maximized primary productivity and carbonate dissolution at around 23.5–22.5 Ma. We
estimate that coccolith production was ~0.15–0.50 g carbonate/kyr/cm2, which corresponds to ~15–56% total carbonate
flux at the study sites. Scanning electron microscope (SEM) observations revealed that ~5–30% of coccolith carbonate
was dissolved during sinking. The concurrent peaks of primary productivity and carbonate dissolution intensity indicatethat organic carbon respiration may have enhanced coccolith dissolution. We propose that the decline in the carbonate
pump weakened the removal of TA from the ocean’s surface to its depths. Consequently, the enhanced buffering capacity of the ocean likely played a role in the drawdown of pCO2 from the late Oligocene to the Early Miocene.

78

INA19

Evidence of the mid-Valanginian Weissert Event in the
Zagros Basin in Iran based on calcareous nannofossils andcarbon isotope data
Azam Mahanipour

Shahid Bahonar University of Kerman, Department of Geology, Faculty of Science, Kerman, Iran; a_mahanipour@uk.ac.ir

Katayoon Barmakizadeh

Shahid Bahonar University of Kerman, Department of Geology, Faculty of Science, Kerman, Iran; katayoon.barmakizadeh@gmail.com

Jörg Mutterlose

Ruhr-Universität Bochum, Institut für Geologie, Mineralogie & Geophysik, 44780 Bochum, Germany; joerg.mutterlose@rub.dehttps://doi.org/10.58998/jnr3253
The mid-Valanginian Weissert Oceanic Anoxic Event is one of the most important paleoceanographic events of the
Early Cretaceous that is characterized by a positive excursion in the carbon isotope data, crisis in the nannoplankton association, and climate changes. In this study, calcareous nannofossils and carbon isotope data were investigated from thelower part of the Garau Formation in the Kabir-Kuh anticline, and they confirm the presence of the Weissert Event in the
Zagros Basin in western Iran (central Tethys). Two positive excursions in the carbon isotope data (2.8‰ and 2.4‰) wererecorded from the middle part of nannofossil Subzone NK3a and the middle part of the Subzone NK3b–NC4a transition
that are comparable to placement in other parts of the Tethyan Realm: the Vocontian Basin in France (e.g., DuchampAlphonse et al., 2007), the Umbria-Marche Basin in central Italy, and the Subbetic Basin in Spain and SW Morocco, as
well as in the Weddell Sea Basin in Antarctica.
In the Zagros Basin, we recorded a simultaneous increase in the relative abundance of warm and eutrophic taxa like
Diazomatolithus lehmanii, Rhagodiscus asper, and Cyclagelosphaera margerelii, which might be related to the ParanáEtendeka volcanism. An increase in the relative abundance of D. lehmanii was also recorded from other parts of the
Tethyan Realm (e.g., Erba et al., 2004). A low relative abundance of nannoconids (less than 5%) was recorded except
for in a few samples. This assemblage was followed by a high relative abundance of Discorhabdus ignotus in the early
Hauterivian, which indicates cool surface water conditions (e.g., Mattioli et al., 2014). These data are accompanied by adecrease in the carbon isotope data to 0.7‰. The Weissert Oceanic Anoxic Event has now been confirmed in the central
Tethys in the Zagros Basin in Iran, which further supports a wide paleoceanographic distribution for this event.
References:
Duchamp-Alphonse, S., Gardin, S., Fiet, N., Bartolini, A., Blamart, D. & Pagel, M. 2007. Fertilization of the northwestern Tethys (Vocontian Basin,
SE France) during the Valanginian carbon isotope perturbation: Evidence from calcareous nannofossils and trace element data. Palaeogeography,
Palaeoclimatology, Palaeoecology, 243: 132–151. https://doi.org/10.1016/j.palaeo.2006.07.010
Erba, E., Bartolini, A. & Larson, R.L. 2004. Valanginian Weissert oceanic anoxic event. Geology, 32: 149–152. https://doi.org/10.1130/G20008.1
Mattioli, E., Pittet, B., Riquier, L. & Grossi, V. 2014. The mid-Valanginian Weissert Event as recorded by calcareous nannoplankton in the Vocontian
Basin. Palaeogeography, Palaeoclimatology, Palaeoecology, 414: 472–485. https://doi.org/10.1016/j.palaeo.2014.09.030

INA1979

Evidence of Discoaster multiradiatus size variation in the latePaleocene–early Eocene of the Zagros Basin (SW Iran)
Azam Mahanipour

Shahid Bahonar University of Kerman, Department of Geology, Faculty of Science, Kerman, Iran; a_mahanipour@uk.ac.ir

Samira Nejadsahebi

Shahid Bahonar University of Kerman, Department of Geology, Faculty of Science, Kerman, Iran; samira.sahebi@sci.uk.ac.ir

https://doi.org/10.58998/jnr3254
The Paleocene/Eocene boundary is associated with an abrupt global warming known as the Paleocene–Eocene Thermal
Maximum (PETM) that occurred at about 55 Ma and coincided with a negative carbon isotope excursion in all ocean
basins. At the PETM, there were also changes in calcareous nannofossils assemblages, such as an increase in abundanceof the genera Rhomboaster and Discoaster. In the current study, calcareous nannofossils were investigated at the Gurpi
anticline in the Zagros Basin in SW Iran (central Tethys). A morphometric analysis of Discoaster multiradiatus indicates a remarkable increase in the size of this species in the upper part of Biozone CNP11/NP9 within the PETM. The
top of Zone CNP11 is marked by the disappearance of the Fasciculithus richardii group. The extinction of this groupis regarded as a marker for the beginning of the PETM at the Paleocene/Eocene boundary in the Atlantic, Pacific, andTethyan Oceans. In other parts of the world, the PETM has been recorded in the upper part of Biozone CNP11/NP9.
Within the studied interval from Zagros Basin, there was a reversed trend in the relative abundance of Toweius spp.
and Coccolithus pelagicus, followed by a decreasing trend in the relative abundance of these two groups of taxa. An
increase and subsequent decrease in the relative abundance of Fasciculithus spp. was also identified before their disappearance and extinction in the PETM and post-PETM interval. Warm and oligotrophic conditions were recorded during
the PETM of the studied interval where an increase in the size of D. multiradiatus was recorded. According to Tremolada et al. (2008), an increase in the size of D. multiradiatus correlates with oligotrophic conditions under enhanced
stratification rather than nitrification.
References:
Tremolada, F., Bernardi, B.D. & Erba, E. 2008. Size variations of the calcareous nannofossil taxon Discoaster multiradiatus (Incertae sedis)
across the Paleocene–Eocene thermal maximum in ocean drilling program holes 690B and 1209B. Marine Micropaleontology, 67: 239–254.
https://doi.org/10.1016/j.marmicro.2008.01.010

80

INA19

Distribution and diversity of coccolithophore communities
living in the tropical and subtropical South Atlantic: Preliminary results from AMT28
Federico Malavolta

Università degli Studi di Milano-Bicocca, Dipartimento di Scienze dell’Ambiente e della Terra, 20126 Milano, Italy; Universidade de Lisboa,
Faculdade de Ciências, Campo Grande, 1749-016 Lisboa, Portugal; f.malavolta1@campus.unimib.it

Mario Cachão

University of Lisbon, Department of Geology, Faculty of Sciences & Instituto Dom Luiz, Campo Grande 1749-016 Lisboa, Portugal;
mcachao@fc.ul.pt

Elisa Malinverno

Milano-Bicocca University, Department of Geological Sciences and Geotechnologies, 20126, Milan, Italy; elisa.malinverno@unimib.it,

Catarina V. Guerreiro

Universidade de Lisboa, Faculdade de Ciências, MARE, Marine and Environmental Science Centre, Campo Grande, 1749-016 Lisboa, Portugal;
cataguerreiro@fc.ul.pt

https://doi.org/10.58998/jnr3255
Coccolithophores, a group of unicellular nannophytoplankton chromists belonging to the Division Haptophyta, playa crucial role in oceanic ecosystems and global biogeochemical cycles. These communities are affected by changes
in seawater temperature, nutrient availability, and sunlight conditions linked to the meridional variations of the mixed
layer dynamics. Here, we present new data on coccolithophore communities living in the tropical and subtropical South
Atlantic based on biological and hydrological data collected along a meridional transect (AMT28) of 16 stations extending from the equatorial region to the Tropic of Capricorn (0–30ºS). The aim of this study is to gather information on
how variations in environmental parameters influence the distribution and diversity of coccolithophores living in thisheavily stratified region. This information is critical for understanding how these important primary producers are likely
to respond to ongoing and future climate changes, and their associated impacts on the biogeochemical cycles that they
influence.
Our preliminary results identified a total of 54 taxa, of which 42 contributed to >5% of the assemblage in at least oneof the samples studied. Taxa contributing <5% of all studied samples on average were 1% of the studied coccolithophorecommunity. The identified taxa were subsequently grouped into 19 taxonomic categories (by genus and/or ecologicalsimilarity) to facilitate exploration of the data and focus on the most abundant taxa. The region of highest coccolithophore abundance (coccospheres/liter) was the South Atlantic equatorial region (0–8°S). To the south of the equatorialarea, abundances became much lower in the upper photic zone, particularly in the region where the deep chlorophyllmaximum (DCM) was deeper along the gyre, despite slightly increasing again around 24–27°S. The Shannon-Wiener
diversity index was higher to the south of the equatorial region but did not show a clear distribution pattern along thetransect. Enhanced species diversity was noticed along the entire photic zone in the region where the DCM was deeper
along the gyre, and slightly more bound to the DCM to the south (24–25°S) and to the north (7–12°S) of the gyre center.
Emiliania huxleyi was more abundant near the surface in the equatorial region (3–7°S) but clearly bound to the DCM
to the south of this area. Umbellosphaera spp. were clearly more abundant in the upper photic zone to the south of theequatorial region, whereas Florisphaera profunda was most abundant along and below the DCM across the transect,particularly along 2–25ºS. Finally, Oolithotus spp. were clearly more abundant along the DCM in the northern part ofthe studied transect (2–12ºS). The next step in this ongoing study will be to compare the newly obtained ecological datawith environmental parameters measured along the photic zone during the cruise, and with previous coccolithophorestudies from the Atlantic Ocean, including the North Atlantic region, which was also sampled during the same AMT28
cruise.

INA1981

Coccolithophore seasonal export production and fluxes in the
Ionian Sea, eastern Mediterranean (June 2004–September
2005)
Elisa Malinverno

University of Milano-Bicocca, Department of Earth and Environmental Sciences, 20126 Milano, Italy; elisa.malinverno@unimib.it

Patrizia Maiorano

University of Bari, Department of Earth and Geoenvironmental Sciences, 70125 Bari, Italy; patrizia.maiorano@uniba.it

Anouk van Boxtel

NIOZ - Royal Netherlands Institute for Sea Research, Department of Ocean Systems, 1790 AB Den Burg, Texel, The Netherlands; Utrecht University, Department of Earth Sciences, 3584 CB Utrecht, The Netherlands; anouk.van.boxtel@nioz.nl

Addison Rice, Gert de Lange

Utrecht University, Department of Earth Sciences, 3584 CB Utrecht, The Netherlands; a.h.rice@uu.nl; g.j.delange@uu.nl

https://doi.org/10.58998/jnr3256
Coccolithophores are a major phytoplankton group in the oligotrophic eastern Mediterranean and make a significant
contribution to the biogenic sediments on the seafloor. The vertical stratification and seasonal succession of species, aswell as the alternation of haplo–diploid phases of their life cycle, allow coccolithophores to exploit different ecologicalniches year-round. Understanding these patterns and the subsequent mechanisms of settling through the water column
is key to unravelling the role of coccolithophore species as paleoceanographic proxies.
Here we present a 15-month (June 2004–September 2005) time series of coccolithophore export production andfluxes from sediment trap samples at 500, 1500, and 3000 m water depths with the aims of linking the seasonal exportof species to the seasonal oceanographic and external forcing and tracing the sinking speed and the modifications of theexport flux with depth. The peak in total mass and coccolithophore fluxes occurred in early summer. Emiliania huxleyi
dominated the coccolith and coccosphere fluxes for most of the year and displayed the highest relative abundance inMarch, whereas the deep-dwelling Florisphaera profunda made a higher contribution during late summer and early
autumn. Minor species that occur year-round in the flux were represented by Syracosphaera pulchra, Umbellosphaera
tenuis, Rhabdosphaera clavigera, Umbilicosphaera foliosa, Helicosphaera carteri, and Calcidiscus leptoporus. Other
minor species and the holococcolithophore phases only occurred during the summer peak of flux.

82

INA19

Size and morphological changes in Coccolithus pelagicus
across the Danian and their link to environmental recovery
from the K/Pg mass extinction in the SE Tethys, Israel
Sara Marconato

Ben-Gurion University of the Negev, Beer-Sheva, 84105, Israel; saramarc@post.bgu.ac.il

Nicolas Thibault

University of Copenhagen, IGN, Copenhagen, DK-1350, Denmark; nt@ign.ku.dk

Sigal Abramovich

Ben-Gurion University of the Negev, Beer-Sheva, 84105, Israel; sigalabr@bgu.ac.il

Sarit Ashckenazi-Polivoda

Dead Sea and Arava Science Center, Masada National Park, Mount Masada, 86910, Israel; sarit@adssc.org

Yoav Oved Rosenberg

Geological Survey of Israel, Jerusalem, 9692100, Israel; yoavr@gsi.gov.il

https://doi.org/10.58998/jnr3257
Coccolithus pelagicus has been the object of numerous biometric studies of Recent and Neogene nannoplankton assemblages. However, so far, despite several biometric studies pointing at a significant increase in size of emergent Danianlineages in the early Paleogene, there has not been any studies assessing morphological changes in C. pelagicus during its
early evolutionary history. To perform this study, 50 specimens per sample of C. pelagicus were counted and measured
with the image software ImageJ across the first 26 m of the Danian of the Hor Hahar section, Zin Basin, (30°49'46.96"N,
35°3'22.40"E, 160 m above sea level). For the first time, we report a distinction between distinctly circular and broadly
elliptical lineages. Moreover, our preliminary results suggest that not less than six morphotypes co-existed in the Danianof Hor Hahar with a dominant elliptical morphotype ranging between 5 and 10 μm. We also observed a constant increasein the length and width of the whole lineage through the Danian, as was previously documented in the tropical Atlantic
Ocean and which probably indicates the progressive establishment of more stable paleoenvironmental conditions.

INA1983

Orbitally paced bottom-water acidification episodes linked to
the late Maastrichtian warming event: Calcareous nannofossil evidence in the Hor Hahar section, Israel
Sara Marconato

Ben-Gurion University of the Negev, Beer-Sheva, 84105, Israel; saramarc@post.bgu.ac.il

Nicolas Thibault

University of Copenhagen, IGN, Copenhagen, DK-1350, Denmark; nt@ign.ku.dk

Thierry Adatte

University of Lausanne, Institute of Earth Sciences, Lausanne, 1015, Switzerland; Thierry.Adatte@unil.ch

Sigal Abramovich

Ben-Gurion University of the Negev, Beer-Sheva, 84105, Israel; sigalabr@bgu.ac.il

Sarit Ashckenazi-Polivoda

Dead Sea and Arava Science Center, Masada National Park, Mount Masada, 86910, Israel; sarit@adssc.org

Yoav Oved Rosenberg

Geological Survey of Israel, Jerusalem, 9692100, Israel; yoavr@gsi.gov.il

https://doi.org/10.58998/jnr3258
The late Maastrichtian was characterized by a pronounced abrupt global warming of 3–4°C from 66.3 to 66.1 Ma and by
episodes of Deccan flood volcanism. A number of previous studies also observed a large increase in fragmentation ofplanktonic foraminifera, accompanied by a decrease in species richness of calcareous planktonic microfossils, which are
related to a “dissolution” event in the late Maastrichtian. These observations have been tentatively linked to a significant
lowering of seawater alkalinity in sea surface waters.
Here, we report new results on absolute and relative abundances of late Maastrichtian calcareous nannofossils fromthe Hor Hahar section in the Zin Basin, Negev Desert (30°49'46.96"N, 35°3'22.40"E, 160 m above sea level). A cyclostratigraphic study, which was performed on high-resolution elemental data acquired by X-ray fluorescence, constrains the section to the last ~410 kyr of the Maastrichtian, hence spanning the final Maastrichtian Deccan episodes andthe late Maastrichtian warming event. Our high-resolution study of nannofossils, performed on 126 samples, revealed
that the most abundant taxa are members of the highly solution-resistant group Micula spp., which, in some cases,
constitute up to 80% of the whole assemblage. We observed a trend of increasing dissolution and high-frequency oscillations in the relative abundance of “robust” recrystallized specimens of Micula staurophora. These oscillations exhibit
an out-of-phase relationship to a precession filter output obtained from the Si signal, attesting to an orbital pacing of
early diagenetic phenomena, which is only possible if sediment pore waters, and hence bottom waters, were regularly
affected by episodes of low alkalinity, possibly at insolation maxima. The timing of the first occurrence of recrystallized
Micula, and an associated drop in the solution-susceptible species Biscutum constans, at 280 kyr before the Cretaceous/
Paleogene boundary, nearly coincides with the onset of the Deccan greenhouse warming.

84

INA19

Reconstruction of the ocean surface dynamics of the Iberianmargin in the Miocene–Pliocene using calcareous nannofossil assemblages
Laura Martín-García

Universidad de Salamanca, Departamento de Geología, Salamanca, Spain; lauramaga@usal.es

Francisco J. Jiménez-Espejo

Instituto Andaluz de Ciencias de la Tierra CSIC, Granada, Spain; fjjspejo@ugr.es

William Clark

University of Alabama, Department of Geological Sciences, Tuscaloosa, AL 35487, USA; wclark15@crimson.ua.edu

Barbara Balestra

American University, Department of Environmental Science, Washington DC, 20016, USA; balestra@american.edu

José-Abel Flores

Universidad de Salamanca, Departamento de Geología, Salamanca, Spain; flores@usal.es

https://doi.org/10.58998/jnr3259
The Iberian margin is a unique location on our planet. It has a shallow continental shelf that is delimited by deep submarine canyons. Portugal's continental shelf rapidly transports sediments through rivers to the ocean floor of the Iberianmargin where it records continental climate signals and changes in ocean dynamics. Previous studies of marine sediments in the region have shown that sedimentary records, which can be correlated with terrestrial and ice volume global
records from Greenland and Antarctica, are related to astronomical (orbital) cyclicity.
Using Miocene–Pliocene sedimentary material recovered from the International Ocean Discovery Program (IODP)
Site U1587, located in the southwest of the Iberian margin, calcareous nannofossil assemblages were analyzed to reconstruct changes in surface-water masses and environmental parameters, such as temperature and surface-water productivity. Calcareous nannofossils were used to illustrate the effect of astronomical dynamics on the marine-continental
relationship at the Miocene/Pliocene boundary.
The studied sedimentary sequence contains alternations of dark and lighter materials, reflecting a cyclicity linked
to the astronomical response. The calcareous nannofossil assemblages also respond to these patterns, as evidenced by
the abundance of Coccolithus pelagicus (cold water species) with respect to Discoaster (warm water taxa). Moreover,
the abundance of total nannoliths per gram of sediment is also affected by this trend. In addition, intervals have been
identified that contain an increase in the number of Reticulofenestra morphotypes with a closed central area. This has
been observed in all sizes of Noelaerhabdaceae: smallest sizes (<5 μm), medium sizes (between 5 and 7 μm), and larger
sizes (>7 μm). This observation could be related to high calcification intervals in the surface water of the ocean. In thissuccession, darker colored sediment intervals are consistent with a scenario of maximum insolation: wet intervals withincreased continental rainfall and a resulting increased supply of detrital material being deposited in the basin. Lighter
colored sediment levels are consistent with a scenario of minimum insolation: less rainfall, higher planktonic production, and more continental aridity. However, other global or regional processes, particularly some related to dynamics ofthe subtropical gyre, could interfere and modify the pattern.

INA1985

Revisedcalcareous
nannofossil
biostratigraphy
andchemostratigraphy for the late Turonian–early Campanian at
Seaford Head (southern England)
Francesco Miniati

Institute of Geosciences and Earth Resources (IGG), National Research Council of Italy (CNR), 50121 Firenze, Italy; francesco.miniati@igg.cnr.it

Nicolas Thibault, Johannes Monkenbusch

University of Copenhagen, Department of Geosciences and Natural Resource Management, DK-1350 Copenhagen C, Denmark; nt@ign.ku.dk;
Johannes.Monkenbusch@web.de

Ian Jarvis

Kingston University London, Department of Geography, Geology and the Environment, Kingston-upon-Thames KT1 2EE, UK;i.jarvis@kingston.ac.uk

Elisabetta Erba

University of Milan, Department of Earth Science "A. Desio," 20133 Milan, Italy; elisabetta.erba@unimi.it

https://doi.org/10.58998/jnr3260
The Seaford Head section is exposed along the sea cliffs on the south coast of England between Brighton and Eastbourne
in the county of Sussex (50.7644°N, 0.1087°E; 50.7561°N, 0.1388°E). The succession comprises upper Turonian–lower
Campanian white nannofossil chalk with a large number of named marls, flint layers, and fossil-rich beds, which provide
excellent marker beds that can be traced through the Anglo-Paris Basin. The available stratigraphic framework consistsof lithostratigraphy, chemostratigraphy, and biostratigraphy that is based on macrofossils, microcrinoids, and microfossils (calcareous nannofossils and benthic foraminifera).
This study aims to revise the calcareous nannofossil biostratigraphy of the late Turonian–early Campanian intervaland calibrate it to a new high-resolution carbonate δ13C record that spans the upper Turonian–middle Santonian of the
Seaford Head section. A total of 68 samples (1 sample/2 m) were analyzed for calcareous nannofossil content, and 712
samples (1 sample/10 cm) were measured for stable carbon isotopes. Changes in calcareous nannofossil assemblages
were evaluated both in terms of semiquantitative and quantitative data with at least 300 specimens counted in each slide.
Four different types of biohorizons were coded as follows: Base (B), Top (T), Base common (Bc), and Top common(Tc) occurrences.
We applied the available calcareous nannofossil biozonations for the Late Cretaceous (CC zones, the integrated NC*
zones, UC zones, and the Boreal UCi subzones). The calcareous nannofossil biostratigraphy was then integrated with
the new stable carbon isotope chemostratigraphy. Absolute abundance patterns of marker taxa allow for a more accurate overview of the biohorizons and the definition of a revised, high-resolution calcareous nannofossil biostratigraphic
framework for the Seaford Head section. This approach proves to be particularly useful in chalk sea deposits where
processes of reworking and redeposition of sediments commonly occur.

86

INA19

Drivers of Neogene coccolithophore macroevolution
Amy P. Murphy

Network Stratigraphic Consulting Ltd., Harvest House, Potters Bar, Herts, EN6 3JF, UK; amy@network-stratigraphic.co.uk

Flavia Boscolo-Galazzo

University of Bremen, MARUM, Center for Marine Environmental Sciences, 28359 Bremen, Germany; fboscologalazzo@marum.dePaul N. Pearson

University College London, Department of Earth Sciences, London, WC1E 6BT, UK; p.pearson@ucl.ac.uk

Tom Dunkley Jones

University of Birmingham, School of Geography, Earth and Environmental Science, Birmingham, B15 2TT, UK; t.dunkleyjones@bham.ac.uk

https://doi.org/10.58998/jnr3261
This study aims to investigate the driving mechanisms of macroevolutionary changes in Neogene nannofossil communities. We provide a global perspective into the macroevolutionary drivers that have influenced coccolithophore communities over the last 15 million years during Neogene cooling. Two datasets are analyzed: (1) a low-resolution (~2.5
Myr sample spacing) global comparison of nine sites spanning the Atlantic, Indian, Pacific, and Southern Ocean basinsand (2) a high-resolution (200 kyr sample spacing) dataset from International Ocean Discovery Program (IODP) Expedition 363, Site U1482 (7.7–1.7 Ma) that document the critical Late Miocene to Early Pleistocene interval. These highresolution data are from a representative tropical, high-diversity succession with apparent continuous recovery throughthis key interval. The Family Noelaerhabdaceae were greatly impacted by declining pCO2 with an overall decrease in
Reticulofenestra coccolith size beginning in the Late Miocene. In contrast, Gephyrocapsa spp. increased in abundance
concurrently, signifying that multiple controlling factors were influencing nannoplankton communities by the end of
the Miocene. New evidence demonstrates that the role of a deepened nutricline prompted macroevolution of coccolithophores and was a greater forcing influence than pCO2 alone. The following adaptive changes within communities wererecognized: the decline of Reticulofenestra coccolith size, the extinction of Discoaster spp. in the Early Pleistocene, andthe increased abundance of Florisphaera profunda, a deep-photic zone taxon.

INA1987

Spatio-temporal variability of alkenone and calcareous
nannofossil abundance records across the southeastern
Philippines: Insights on alkenone production and paleoceanographic reconstructions
Justin Jorge R. Padre

University of the Philippines Diliman, Nannoworks Laboratory, National Institute of Geological Sciences, Quezon City 1101 Philippines;
jrpadre@up.edu.phAlyssa M. Peleo-Alampay, Allan Gil S. Fernando

University of the Philippines, Diliman, National Institute of Geological Sciences, Nannoworks Laboratory, Quezon City 1101 Philippines;
ampeleoalampay@up.edu.ph; asfernando@up.edu.phTimothy D. Herbert

Brown University, Department of Earth, Environmental and Planetary Sciences, Providence, Rhode Island, 02912 USA;timothy_herbert@brown.edu

Angel T. Bautista VII, Jeff Darren G. Valdez, Alexandria M. Tanciongco
Philippine Nuclear Research Institute, Department of Science and Technology, Diliman, Quezon City 1101 Philippines; atbautistavii@pnri.dost.
gov.ph; jdgvaldez@pnri.dost.gov.ph; amtanciongco@pnri.dost.gov.phHiroyuki Matsuzaki, Yoko S. Tsuchiya

University of Tokyo, Micor Analysis Laboratory, Tandem Accelerator (MALT), Tokyo, 113-0032 Japan; hmatsu@um.u-tokyo.ac.jp; suno@um.utokyo.ac.jp

https://doi.org/10.58998/jnr3262
Southeastern Philippines is located near the center of the Western Pacific Warm Pool (WPWP), a large, oceanic warmwater mass located in the tropical western Pacific with a characteristic mean sea surface temperature of >28°C. Several
water masses meet in this area as part of the global thermohaline circulation that distributes mass and heat throughout
the world. Study of the oceanographic variability in this area has aided understanding of the role that the tropics play inheat and mass transfer and subsequent climate change. Recent studies have proposed the use of coastal basin areas withhigh sedimentation rates as potential sites of high-resolution records that can be used to reconstruct centennial, decadal,
and interannual scales of climate variability over the recent past.
Alkenones are long-chain organic compounds produced by haptophytes in the Order Isochrysidales that are primarily
produced in the marine realm by the coccolithophorid species Emiliania huxleyi and Gephyrocapsa oceanica. The degree of unsaturation of these compounds, based on the ratio of di- and tri-unsaturated alkenone compounds as expressedby the alkenone unsaturation index (U K'
37 ), provides a correlation to mean annual sea surface temperature, whereas alkenone concentrations have been considered to correlate with surface productivity. There is a large potential for correlating
alkenone concentration with calcareous nannofossil abundance proxy records to provide a broader, multiproxy approachin reconstructing past oceanographic conditions, particularly in sites of high sedimentation rates.
Here, we present downcore results from three multicore sites across the southeastern Philippines (eastern Mindanao
and the Davao Gulf) that were used to explore the potential of determining sea surface temperature and productivity
reconstructions during the Holocene using alkenone and calcareous nannofossil abundance proxy records. Preliminary
results show that Florisphaera profunda dominates the assemblage, followed by Gephyrocapsa oceanica and Emiliania
huxleyi. Coccolith abundance, species diversity, and net primary productivity indices decrease across all sites, coinciding with an alkenone-derived decrease in sea surface temperature. In terms of alkenone production and dominant
haptophyte assemblages, there is a higher positive correlation between G. oceanica abundances and UK'
37 values than E.
huxleyi. Due to constraints with age dating results, we can only provide age-dated variability for one site, which faces thePhilippine Sea. The overall variation shows a slight warming trend over the last 2000 years, accompanied by a decreasing trend of net surface primary productivity.

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Leveling the gap between different counting techniques incoccolithophore cultures
Elisa Palandri

National Institute of Oceanography and Applied Geophysics – OGS, 34151, Trieste, Italy; epalandri@ogs.it

Elena Di Poi, Federica Camisa, Cinzia de Vittor

National Institute of Oceanography and Applied Geophysics – OGS, 34151, Trieste, Italy; edipoi@ogs.it; fcamisa@ogs.it; cdevittor@ogs.it

Adriano Carrara, Davide Alberti

A2A S.p.A, via Lamarmora 230 – 25124, Brescia, Italy; adriano.carrara@a2a.it; davide.alberti@a2a.it

Manuela Bordiga

National Institute of Oceanography and Applied Geophysics – OGS, 34151, Trieste, Italy; mbordiga@ogs.it

https://doi.org/10.58998/jnr3263
Monospecific cultures of coccolithophores are fundamental to exploring species-specific response to various controllingparameters (temperature, pH, CO2, etc.). Acquiring the most accurate values for cell counting is fundamental to correctly
quantifying the maximum cellular density and growth rate, which are pivotal for studying the culture response, especially when it comes to comparing the results among different laboratories. We tested two of the most commonly usedcell counting methods to identify which approach has the highest accuracy and speed for evaluating a culture’s cellulardensity (cells/mL): Sedgewick Rafter chamber or Bürker counting chamber. Moreover, because manual cell counts aretime consuming, we compared them with the culture absorbance (i.e., optical density [OD]) measured with a spectrophotometer, a poorly used method for coccolithophores but extremely useful for high density cultures and to speed up thecounting process. These methodologies were tested on three different species of coccolithophores: Helicosphaera carteri,
Chrysotila carterae, and Emiliania huxleyi (from Roscoff Culture Collection) that cover a wide range in cellular densities
and cell sizes, from lower cell density (~3 × 105 cells/mL) and larger size (20 µm) for H. carteri to higher cellular density(>5 × 106 cells/mL) and smaller size (5 µm) for E. huxleyi.
The preliminary data document that the Sedgewick Rafter chamber can be confidently used from very low cellulardensities (e.g., 500 cells/mL) to higher counts (~3 × 105 cells/mL), maintaining a low standard deviation among the replicates. Above this upper limit, culture dilution is necessary when using the Sedgewick Rafter chamber to avoid increasing
errors from the human operator. Dilution at higher cellular densities can be avoided using the Bürker chamber, which also
returns good results with low standard deviations for cellular densities above 106 cells/mL and for small-sized species.
Indeed, small-sized species, such as E. huxleyi, can make the manual counting more difficult with the Sedgewick Rafter
chamber, which has fewer guide grids compared to the Bürker chamber. All the above-mentioned counts can be linearlycorrelated with OD measurements at a specific wavelength (750 nm) according to the Lambert-Beer law within the validity range of 0.1–1. Both manual counting methods provided good coefficients of determination (>0.9 when correlatedwith the OD), indicating that the number of cells is well described by OD in the selected range.
Our data show that the Sedgewick Rafter chamber is an effective method for physiological studies, where lower cellular densities are commonly used. On the other hand, the Bürker chamber is more suitable for higher cellular densities
required for biotechnological studies. Finally, although the OD is not commonly used for monitoring coccolithophore
growth, we recommend the use of OD measurements to speed up data collection, particularly for high cell density studies
that focus on coccolithophore productivity for practical applications.
Acknowledgements:

This research was funded by the Company A2A S.p.A., Italy's largest multi-utility company, within the project COLMARE “CO2 Lowering through Marine microAlgae Resilience and Exploitation”. We would also like to thank the IPANEMA HR project (CIR01_00018 “Implementazione del laboratorio naturale ECCSEL di Panarea e dell’osservatorio
marino – Rafforzamento del capitale umano”) for funding the first author's research grant.

INA1989

Coccolith dynamic distribution in the western tropicalAtlantic during the last 300,000 years: Toward a better understanding of oceanic current dynamics
Guilherme Pedrão

University of Paris-Saclay, Geosciences Paris-Saclay Laboratory, Centre National de la Recherche Scientifique, 91405 Orsay, France; Institut Français de Recherche pour l’Exploitation de la Mer (IFREMER), Plouzane, France; guilherme.pedrao@universite-paris-saclay.fr

Stéphanie Duchamp-Alphonse, Julius Nouet

University of Paris-Saclay, Geosciences Paris-Saclay Laboratory, Centre National de la Recherche Scientifique, 91405 Orsay, France;
stephanie.duchamp@universite-paris-saclay.fr; julius.nouet@universite-paris-saclay.fr

Natalia Vázquez Riveiros

Centre National de la Recherche Scientifique, UMR 6538 Geo-Ocean, IFREMER, UBO, Plouzané, France; Natalia.Vazquez.Riveiros@ifremer.fr

Rodrigo Nascimento

Universidade Federal do Paraná, Paraná, Brazil; rodrigoan@id.uff.br

Felipe Toledo, Karen Costa

Universidade de São Paulo, São Paulo, Brazil; ftoledo@usp.br; karen.costa@usp.br

Ana Luiza Albuquerque

Universidade Federal Fluminense, Rio de Janeiro, Brazil; ana_albuquerque@id.uff.br

https://doi.org/10.58998/jnr3264
In tropical regions, trade winds related to the Intertropical Convergence Zone (ITCZ) shape ocean surface circulation
with a significant impact on latitudinal heat transport. This is particularly the case in the western tropical Atlantic (WTA)
that is characterized by several surface currents: the South Equatorial Current, the Brazil Current, and the North Brazil
Current, which contribute to a unique northward, cross-equatorial transport of heat and salt. The dynamics of these currents in the geologic past remains unclear, preventing us from having a clear overview of how they may have affectedcross-equatorial flow and the associated heat transport.
In this study based on coccolith assemblage analyses of marine sediment core GL-1180 retrieved in the WTA(8°27'18"S, 33°32'53"W, 1037 m water depth), we explore productivity patterns over the past 300,000 years to track
variations in the expansion of the nutrient-rich South Atlantic Central Water (SACW) at orbital scales and try to understand how it may impact the Brazil Current system. In addition, based on total coccolith abundance (TCA) and proportions of lower photic zone (LPZ) species, such as Florisphaera profunda and Gladiolithus flabellatus, together with
subsurface temperature data, we aim to trace nutricline dynamics and interpret them in terms of stratification versus
mixing of the upper to intermediate water column.
Preliminary results show that ~90% of the coccolith assemblages were represented by F. profunda, Gephyrocapsa
spp., Emiliania huxleyi, and G. flabellatus. Subtropical species, such as Umbellosphaera spp., Syracosphaera spp.,
Discosphaera tubifera, and Umbilicosphaera spp., were also observed, but altogether, they did not exceed 15% of theassemblage. The coccoliths had moderate to excellent preservation. The LPZ species F. profunda and G. flabellatus
dominated the assemblages when precession was low, suggesting a relatively deep nutricline, stratified waters, andprobable oligotrophic conditions in the upper photic zone. Gephyrocapsa spp. only dominated during the high precession periods of Marine Isotope Stages 8 and 9, which might indicate a shallower nutricline and higher paleoproductivity when meso-eutrophic conditions prevailed. Higher Gephyrocapsa spp. abundances were concomitant with higher
TCA and lower subsurface temperatures, whereas higher LPZ species abundances were associated with lower TCA andhigher subsurface temperatures. It is probable that heat accumulated in the study area during low precession periods,
which are associated with a weakening of the North Brazil Current and a southward migration of the ITCZ prevented
any influence of the SACW and, hence, hampered nutrient input into the photic zone. In contrast, we likely observed an
influence of intermediate SACW for periods of high precession.

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Coccolithophore assemblage dynamics and Emiliania
huxleyi morphological patterns during the years 2017–2019 in the Aegean Sea (Greece, NE Mediterranean)
Patrick James Penales

National and Kapodistrian University of Athens, Faculty of Geology and Geoenvironment, Panepistimioupolis, 15784 Athens, Greece; Universityof Lille 1, Department of Earth Sciences, CitéScientifique, CEDEX, 59655 Villeneuve d’Ascq, France; pfpenales@up.edu.phElisavet Skampa, Margarita D. Dimiza

National and Kapodistrian University of Athens, Faculty of Geology and Geoenvironment, Panepistimioupolis, 15784, Athens, Greece;
elskampa@geol.uoa.gr; mdimiza@geol.uoa.gr

Constantine Parinos, Alexandra Gogou, Dimitrios Velaoras

Hellenic Centre for Marine Research, Institute of Oceanography, 19013 Anavyssos, Greece; ksparinos@hcmr.gr; agogou@hcmr.gr;
dvelaoras@hcmr.gr

Maria V. Triantaphyllou

National and Kapodistrian University of Athens, Faculty of Geology and Geoenvironment, Panepistimioupolis, 15784, Athens, Greece;
mtriant@geol.uoa.gr

https://doi.org/10.58998/jnr3265
This study describes the species composition of living coccolithophore communities and the morphological featuresof Emiliania huxleyi from samples collected during expeditions in March 2017, March 2019, and August 2019 in the
Aegean Sea. We investigated spatial and temporal variations using samples collected across six sampling stations tomonitor the coccolithophore assemblages after the exceptionally cold December 2016, which resulted in winter heat loss
and newly produced dense waters that ventilated the Aegean deep basins (Velaoras et al., 2017). Coccolithophores in
the area were relatively diverse, and a total of 51 species were identified using the scanning electron microscope (SEM).
The recorded total cell density in the 2017 winter sampling (maximum 17.8 × 103 cells/L in mid- to lower water depths)
was much lower than the 2019 cold sampling period (up to 27.7 × 103 cells/L documented at 20 m depth). A notablecorroded/malformed morphology of many specimens was observed in the studied samples for winter 2017, especiallyin the deeper parts of the water column. The assemblages displayed distinct seasonality as already documented for the
Aegean Sea domain (Dimiza et al., 2015; Karatsolis et al., 2017) with winter periods characterized by the dominanceof Emiliania huxleyi and Syracosphaera molischii. In contrast, the warm period exhibited higher species richness anddiversity (maximum of 25 taxa observed at the surface layers) and low dominance indices when compared to the colder
season. Summer assemblages featured high absolute abundances of Rhabdosphaera clavigera, Syracosphaera halldalii,
Umbellosphaera tenuis, Algirosphaera robusta, and various holococcolithophores that were dominated mainly by Syracosphaera arethusae HOL, Calyptrosphaera heimdaliae, and Helladosphaera cornifera, which are found primarily inthe upper photic zone. In addition, morphometric analyses conducted on well-developed E. huxleyi coccoliths showed
the characteristic dominance of heavily calcified coccoliths during the cold season in the Aegean Sea (Triantaphyllou etal., 2018) with a slight decrease in the average coccolith length and coccolith width observed between the winter 2017
and winter 2019 sampling periods. This difference is more pronounced in the average tube width and relative tube width,
probably suggesting increased calcification rates occurring in the Aegean Sea water column after the exceptional cold
event of December 2016.
Acknowledgements:

We acknowledge support of this work by the Greek National Project CLIMPACT: Flagship Initiative for Climate
Change and its Impact by the Hellenic Network of Agencies for Climate Impact Mitigation and Adaptation

INA1991

References:
Dimiza, M., Triantaphyllou, M.V., Malinverno, E., Psarra, S., Karatsolis, B.-T., Mara, P., Lagaria, A. & Gogou, A. 2015. The composition and distribution of living coccolithophores in the Aegean Sea (NE Mediterranean). Micropaleontology, 61: 521–540.
Karatsolis, B.-T., Triantaphyllou, M.V., Dimiza, M.D., Malinverno, E., Lagaria, A., Mara, P., Archontikis, O. & Psarra, S. 2017. Coccolithophore assemblage response to Black Sea water inflow into the north Aegean Sea (NE Mediterranean). Continental Shelf Research, 149: 138–150. https://doi.org/10.1016/j.csr.2016.12.005
Triantaphyllou, M.V., Baumann, K.-H., Karatsolis, B.-T., Dimiza, M.D., Psarra, S., Skampa, E., Patoucheas, P., Vollmar, N.M., Koukousioura, O.,
Katsigera, A., Krasakopoulou, E. & Nomikou, P. 2018. Coccolithophore community response along a natural CO2 gradient off Methana (SWSaronikos Gulf, Greece, NE Mediterranean). PLoS ONE, 13(7): e0200012. https://doi.org/10.1371/journal.pone.0200012
Velaoras, D., Papadopoulos, V.P., Kontoyiannis, H., Papageorgiou, D.K. & Pavlidou, A. 2017. The response of the Aegean Sea (eastern Mediterranean) to the extreme 2016–2017 winter. Geophysical Research Letters, 44: 9416–9423. https://doi.org/10.1002/2017GL074761

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Insights into the last glacial–interglacial shift: Microfossils
and geochemical evidence from the Argentine continental
marginJuan Pablo Pérez Panera

Universidad Nacional de La Plata, CONICET, División Geología, Museo de La Plata, Facultad de Ciencias Naturales y Museo, 1900 La Plata,
Buenos Aires, Argentina; perezpanera@gmail.com

Lydia Calvo Marcilese

Universidad Nacional de La Plata, CONICET, División Geología, Museo de La Plata, Facultad de Ciencias Naturales y Museo, 1900 La Plata,
Buenos Aires, Argentina; lydiacalvom@gmail.com

Juan Muglia

CONICET, Centro Para el Estudio de los Sistemas Marinos, Puerto Madryn, Chubut, Argentina; juanmuglia@gmail.com

Lautaro Loyza-Cannatá

Universidad Nacional de La Plata, CONICET, División Geología, Museo de La Plata, Facultad de Ciencias Naturales y Museo, 1900 La Plata,
Buenos Aires, Argentina; lautaroloyza96@gmail.com

Micaela Chaumeil Rodríguez

Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Investigación en Paleobiología y Geología (IIPG, CONICETUNRN). 8332 General Roca, Río Negro, Argentina; micachaumeil@gmail.com

Gabriela Cusminsky

Universidad Nacional del Comahue, CONICET, Centro Regional Universitario Bariloche, Bariloche, Río Negro, Argentina;
gcusminsky@gmail.com

https://doi.org/10.58998/jnr3266
The Argentine Continental Margin (ACM), located in the southwestern Atlantic Ocean, is one of the widest continental
shelves in the world and is the only place in the Southern Ocean were water masses of south polar and equatorial origin
interact. Its micropaleontological and geochemical record is key to understanding the oceanographic and climatic changes
that occurred in the recent past. In this contribution, we present preliminary results on the calcareous nannofossils, foraminifera, and geochemical (total organic carbon [TOC], X-ray fluorescence [XRF], and stable isotopes) records from one
gravity core retrieved in the ACM at the Piedra Buena Terrace (AU_GEO02_GC30: 57.967°S, 44.5202°W; 2756 m water
depth). This core is 678.8 cm long and based on calcareous nannofossil assemblages, which are dominated by Emiliania
huxleyi, is restricted to Subzone NN21b (Rivas, 2023). Absolute dating (14C), measured on bulk sediment and planktonic
foraminifera, indicates a Late Pleistocene to Holocene age. The core can be divided into six alternating barren and fertile
intervals based on calcareous microfossils (nannofossils and foraminifera) that correlate with variations in TOC, δ13Corg,
Mo, S, Al2O3, SiO2, CaO, Sr, P, Ba, and C:N values. These intervals are interpreted to represent advances and retreats of
the Polar Front during Marine Isotope Stages (MIS) 1 to 6. According to productivity (P, Ba) and redox (Mo, S) sensitiveelements and TOC values, primary productivity was slightly enhanced during cold stages, showing a switch to a diatomdominated phytoplankton community. The core AU_GEO02_GC30 represents one of the most complete records for thelast glacial–interglacial transition in the ACM and offers an opportunity to study its impact on oceanography and the
response of the phytoplankton community.
References:
Rivas, L. 2023. Nanofósiles calcáreos neógenos y cuaternarios de testigos del Margen Continental Argentino: sistemática y aportes a la paleoceanografía y a la bioestratigrafía. Unpublished PhD Thesis, Universidad Nacional de La Plata, 329pp.

INA1993

Temperature-dependent calcareous nannofossil export productivity during early Paleogene hyperthermals
Nicolas Pige

Université Claude Bernard Lyon 1, ENSL, CNRS, LGL-TPE, 69622, Villeurbanne, France; nicolas.pige@univ-lyon1.fr

Guillaume Suan, Frédéric Quillévéré

Université Claude Bernard Lyon 1, ENSL, CNRS, LGL-TPE, 69622, Villeurbanne, France; guillaume.suan@univ-lyon1.fr;
frederic.quillevere@univ-lyon1.fr

Pierre-Henri Blard

Université de Lorraine, CRPG, CNRS, 54500 Vandoeuvre-lès-Nancy, France; Laboratoire de Glaciologie, Department of Geosciences, Environment,
Society, ULB, 1050, Brussels, Belgium; pierre-henri.blard@univ-lorraine.fr

Alessandro Menini, Jeremy Höhne, Antoine Triantafyllou, Arnauld Vinçon-Laugier, Emanuela Mattioli
Université Claude Bernard Lyon 1, ENSL, CNRS, LGL-TPE, 69622, Villeurbanne, France; alessandromenini17@gmail.com;
jeremy.hoehne@etu.univ-lyon1.fr; antoine.triantafyllou@univ-lyon1.fr; arnauld.vincon-laugier@univ-lyon1.fr; emanuela.mattioli@univ-lyon1.fr

https://doi.org/10.58998/jnr3267
Oceanic carbonate burial is the main carbon sink on a geological timescale. Deep-sea records of early Paleogene hyperthermals, which are abrupt greenhouse warming events associated with rhythmic massive releases of carbon into
the ocean–atmosphere system, show drastic changes in calcite burial. Such lithologic perturbations have largely been
attributed to chemically induced modulation of deep seafloor calcite preservation.
Here, we use microfossil (nannofossil abundances and planktonic foraminiferal fragmentation) and geochemical
evidence (extraterrestrial 3He) to reconstruct calcareous nannofossil fluxes across ~10 hyperthermals (~57.5–53.5 million years ago) for a North Pacific deep-sea site located above the lysocline. We also calculated the nannofossil fluxes
during the Paleocene–Eocene Thermal Maximum (PETM) at South Atlantic and Southern Ocean sites, using previously
published 3He data, to obtain a global picture of the biotic response of planktonic calcifiers in the open ocean. Overall,
we found a partial decoupling between seafloor saturation and calcareous nannofossil export production. Repeated
40–99% decreases in nannofossil burial across hyperthermals were primarily driven by warming-induced lowering of
nannoplankton-derived calcite export productivity, and secondarily by changing bottom water chemistry. Our results
emphasize that shallow-water (<1000 m) ecosystems and metabolic processes are overlooked as chief mechanisms forregulating carbon cycle feedbacks on a geological timescale.

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Middle to Late Miocene calcareous nannofossil biostratigraphy and paleoecology at Broken Ridge, eastern Indian
Ocean (ODP Site 752)
Xabier Puentes-Jorge

University of Graz, Department of Earth Sciences (Geology and Paleontology), NAWI Graz Geocenter, Graz, Austria;
xabier.puentes-jorge@uni-graz.at

Arianna V. Del Gaudio

University of Graz, Department of Earth Sciences (Geology and Paleontology), NAWI Graz Geocenter, Graz, Austria;
arianna.del-gaudio@uni-graz.at

Jing Lyu, David de Vleeschouwer

University of Münster, Institute of Geology and Paleontology, Münster, Germany; j.lyu@uni-muenster.de; ddevleeschouwer@marum.de

Werner E. Piller, Tamara Hechemer, Gerald Auer

University of Graz, Department of Earth Sciences (Geology and Paleontology), NAWI Graz Geocenter, Graz, Austria; werner.piller@uni-graz.at;tamara.hechemer@uni-graz.at; Gerald.auer@uni-graz.at

https://doi.org/10.58998/jnr3268
The Middle to Late Miocene represents an important time interval in the Indian Ocean due to the reorganization of landmasses and the occurrence of important climatic events, such as the establishment of a near-modern monsoonal windsystem, the Middle Miocene Climatic Transition, and the subsequent northward shift of the westerlies during the Late
Miocene. However, the effect of these forcing mechanisms on intermediate and surface ocean dynamics in the southern
subtropical Indian Ocean remains poorly understood. Ocean Drilling Program (ODP) Site 752, located on the western
flank of Broken Ridge (30°53.475'S, 93°34.652'E), represents a key location for understanding how oceanic currents
may have been affected by the above-mentioned mechanisms in the eastern sector of the Indian Ocean during the studied
Miocene interval.
During ODP Leg 121, an initial biostratigraphic framework for Site 752 was established. However, the limited
biostratigraphic data, due to poor preservation of sediment material for the Middle to Upper Miocene, resulted in a lowresolution shipboard age-depth model. We present here a newly updated high-resolution biostratigraphic age-depth
model based on fully quantitative nannofossil assemblage analyses and planktonic foraminiferal bioevents for the timeinterval between ~15 and ~8 Ma for Hole 752A. The biostratigraphic age-depth model was compared with a recently
published astrochronologically tuned age-depth model (Lyu et al., 2023) for further validation. A high consistency
between models was observed for the whole record, except for the interval between ~13 and 12 Ma, where the age difference is high. We link these discrepancies to the potential variance in age of the recorded bioevents for this interval
between basins, as well as the error associated with the mathematical approach of the tuned age model.
Based on our quantitative nannofossil data, we further evaluated overall changes in the nannofossil assemblages
at ODP Site 752. Unpaired pair group method with arithmetic mean (UPGMA) clustering analyses resulted in five
major clusters. Cluster 1 is characterized by a high abundance of Reticulofenestra minuta (average = 49.25%) and low
abundances of medium (>3 µm) and large (>5 µm) reticulofenestrids. Cluster 2 is defined by a high abundance of Calcidiscus leptoporus and a higher abundance of Umbilicosphaera jafari when compared with the other clusters (averagevalues of 18.34% and 1.42%, respectively). Cluster 3 is characterized by a high abundance of medium-sized (3–5 µm)
reticulofenestrids, whereas Cluster 4 is characterized by a high abundance of Coccolithus pelagicus and Discoaster spp.
(average of 22.56% and 7.38%, respectively). Cluster 5 is defined by a high abundance of Reticulofenestra producta(24.61%) and large reticulofenestrids (>5 µm) such as Reticulofenestra pseudoumbilicus.

INA1995

References:
Lyu, J., Auer, G., Bialik, O.M., Christensen, B., Yamaoka, R. & De Vleeschouwer, D. 2023. Astronomically-Paced Changes in Paleoproductivity,
Winnowing, and Mineral Flux Over Broken Ridge (Indian Ocean) Since the Early Miocene. Paleoceanography and Paleoclimatology, 38(12):e2023PA004761. https://doi.org/10.1029/2023PA004761

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Improving Arctic Quaternary geochronology and paleoceanographic reconstructions using calcareous nannofossils
Mohammad J. Razmjooei

Stockholm University, Department of Geological Sciences; Bolin Centre for Climate Research, Stockholm, Sweden;mohammad.razmjooei@geo.su.se

Matt O’Regan, Helen Coxall, Flor Vermassen, Martin Jakobsson

Stockholm University, Department of Geological Sciences; Bolin Centre for Climate Research, Stockholm, Sweden; matt.oregan@geo.su.se;helen.coxall@geo.su.se; flor.vermassen@geo.su.se; martin.jakobsson@geo.su.se

https://doi.org/10.58998/jnr3269
The challenges of dating Quaternary Arctic Ocean sediments continue to obscure paleoceanographic insights into thehistory of sea ice and the configuration and dynamics of past ice sheets. A key historical problem is that different geochronological tools provide widely different age estimates for the same sedimentary sequences. Calcareous nannofossils
still provide the most robust biostratigraphic age markers for Quaternary Arctic Ocean sediments. However, Arctic sediments are dominated by fine-grained terrigenous material, and they commonly contain rare and poorly preserved coccolith specimens that can be difficult to identify under the light microscope (LM). By developing and applying a paired
LM and scanning electron microscope (SEM) technique for observing the same nannofossil specimens (Razmjooei &O’Regan, 2024, preprint), we recently illustrated how poorly preserved nannofossils, which cannot easily be identified
at the species level, were previously classified as Gephyrocapsa huxleyi using LM observations alone. Moreover, thevisual resemblance between G. huxleyi and another Quaternary marker species, Pseudoemiliania lacunosa, had led tooccasional misdiagnoses (Razmjooei et al., 2023). Proposed revisions to the placement of G. huxleyi and P. lacunosa inthe stratigraphic framework of central Arctic sediment cores can resolve some of the disparity between different dating
techniques and indicate a different chronostratigraphic framework than has been used for nearly two decades of paleoceanographic research. Two key questions that remain include: (1) when did G. huxleyi first enter the Arctic Ocean, and(2) where did it first appear in the lithostratigraphic framework of central Arctic sediments? Despite its relatively recent
emergence (290 ka, Raffi et al., 2006), G. huxleyi exhibits significant morphological diversity. Recent research suggeststhat there were three episodes of evolutionary diversification within this species: before Marine Isotope Stage (MIS) 5,
during MIS 5, and during MIS 1 (Bendif et al., 2023). Our LM-SEM imaging technique reveals two distinct morphotypes
in central Arctic sediments. The first is exclusive to Holocene sediments, whereas the second appears in both Holocene
and older intervals within the Arctic. The occurrence of these different morphotypes in Arctic Ocean sediments may
provide additional important biostratigraphic age control. Testing this requires SEM-based analysis of the crystalline
structures that form coccoliths in both central Arctic sediments with uncertain age control and better dated records fromthe Arctic–Atlantic gateway.
References:
Bendif, E.M., Probert, I., Archonitkis, O.A., Young, J.R., Beaufort, L., Rickaby, R.E. & Filatov, D. 2023. Rapid diversification underlying the global
dominance of a cosmopolitan phytoplankton. The ISME Journal, 17: 630–640. https://doi.org/10.1038/s41396-023-01365-5
Raffi, I., Backman, J., Fornaciari, E., Pälike, H., Rio, D., Lourens, L. & Hilgen, F. 2006. A review of calcareous nannofossil astrobiochronology encompassing the past 25 million years. Quaternary Science Reviews, 25: 3113–3137. https://doi.org/10.1016/j.quascirev.2006.07.007
Razmjooei, M.J., Henderiks, J., Coxall, H.K., Baumann, K.-H., Vermassen, F., Jakobsson, M., Niessen, F. & O’Regan, M. 2023. Revision of the Quaternary calcareous nannofossil biochronology of Arctic Ocean sediments. Quaternary Science Reviews, 321: 108382. https://doi.org/10.1016/j.
quascirev.2023.108382
Razmjooei, M.J. & O’Regan, M. SSRN (Preprint) 16 March 2024. Improved paired light and scanning electron microscope imaging technique for
identifying nannofossils in Arctic sediments. https://doi.org/10.2139/ssrn.4761224

INA1997

Study of the paleoclimatic transition from Greenhouse to Icehouse conditions by means of calcareous nannofossils in theSouthern, Atlantic, Pacific, and Indian OceansDavide Righi

Università degli Studi di Parma, Dipartimento di Scienze Chimiche, della Vita e della Sostenibilità Ambientale - SCVSA, I-43124 Parma, Italy;
davide.righi@unipr.it

Davide Persico, Valentina Catelli

Università degli Studi di Parma, Dipartimento di Scienze Chimiche, della Vita e della Sostenibilità Ambientale - SCVSA, I-43124 Parma, Italy;
davide.persico@unipr.it; valentina.catelli@unipr.it

Chiara Fioroni

Università degli Studi di Modena e Reggio Emilia, Dipartimento di Scienze Chimiche e Geologiche, I-41125, Modena, Italy;
chiara.fioroni@unimore.it

Isabella Raffi

Università degli Studi “G. d’Annunzio” di Chieti-Pescara, International Research School of Planetary Sciences - IRSPS, I-65127 Pescara, Italy;
isabella.raffi@unich.it

Giuliana Villa

Università degli Studi di Parma, Dipartimento di Scienze Chimiche, della Vita e della Sostenibilità Ambientale - SCVSA, I-43124 Parma, Italy;
giuliana.villa@unipr.it

https://doi.org/10.58998/jnr3270
The Eocene–Oligocene transition (EOT) occurred at approximately 34 Ma, lasted approximately 790 kyr, and includes the Eocene/Oligocene boundary (EOB). It marks the transition from a world without permanent ice sheets(Greenhouse conditions) to one with an Antarctic Ice Sheet (Icehouse conditions) (Hutchinson et al., 2021). The EOT
was also a time of major extinctions and ecological reorganization in several biotic groups (Saraswati, 2021) that wasprobably due to several factors. This critical time interval is highlighted by multiple proxies and their correlations(Villa et al., 2014). The response of calcareous phytoplankton to global changes across the EOB is less well understood than other critical intervals such as the Paleocene/Eocene boundary (Dunkley Jones et al., 2008).
We undertook a high-resolution (5–10 cm), quantitative to qualitative analysis to improve the biostratigraphy ofthis interval and carried out a detailed paleoecological interpretation. In this study, 10 sites at low, medium, and highlatitudes were considered with emphasis on understanding paleolatitude and paleobathymetry. Specifically, the objectives of this research work are to (1) reconstruct paleoclimatic and paleoceanographic conditions, (2) improve theframework of the changes that have occurred at different latitudes, (3) improve the knowledge of the effects recordedby calcareous nannofossils, and (4) improve paleoclimatic and paleoceanographic documentation by highlighting
species distribution models.
References:Dunkley Jones, T., Bown, P.R., Pearson, P.N., Wade, B.S., Coxall, H.K. & Lear, C.H. 2008. Major shifts in calcareous phytoplankton assemblages through the Eocene–Oligocene transition of Tanzania and their implications for low-latitude primary production. Paleoceanography, 23:
PA4204. https://doi.org/10.1029/2008PA001640
Hutchinson, D.K., Coxall, H.K., Lunt, D.J., Steinthorsdottir, M., de Boer, A.M., Baatsen, M., von der Heydt, A., Huber, M., Kennedy-Asser, A.T.,
Kunzmann, L., Ladant, J.-B., Lear, C.H., Moraweck, K., Pearson, P.N., Piga, E., Pound, M.J., Salzmann, U., Scher, H.D., Sijp, W.P., Śliwińska,K.K., Wilson, P.A. & Zhang, Z. 2021. The Eocene–Oligocene transition: A review of marine and terrestrial proxy data, models and model–datacomparisons. Climate of the Past, 17: 269–315. https://doi.org/10.5194/cp-17-269-2021
Saraswati, P.K. 2021. Chapter 8: Signals of deep-time climate change. Foraminiferal Micropaleontology for Understanding Earth's History. Elsevier: 237–259. https://doi.org/10.1007/s12040-021-01735-7

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Villa, G., Fioroni, C., Persico D., Roberts, A.P. & Florindo, F. 2014. Middle Eocene to Late Oligocene Antarctic glaciation/deglaciation and Southern
Ocean productivity. Paleoceanography, 29: 223–237. https://doi.org/10.1002/2013PA002518

INA1999

Evolution of coccolithophore communities in the Atlantic
Iberian margin during the Common Era
Andrés S. Rigual Hernández

Universidad de Salamanca, Área de Paleontología, Departamento de Geología, 37008 Salamanca, Spain; arigual@usal.es

José Abel Flores

Universidad de Salamanca, Área de Paleontología, Departamento de Geología, 37008 Salamanca, Spain; flores@usal.esÁurea Narciso

Instituto Português do Mar e da Atmosfera, Divisão de Geologia e Georrecursos Marinhos, 1495 Algés, Portugal; acmnarciso@gmail.com

Lívia Gebara M.S. Cordeiro, Emília Salgueiro, Fátima Abrantes

Instituto Português do Mar e da Atmosfera, Divisão de Geologia e Georrecursos Marinhos, 1495 Algés, Portugal; Universidade do Algarve, CCMAR, Centro de Ciências do Mar, Campus de Gambelas, 8005-139 Faro, Portugal; livia.gebara@ipma.pt; emilia.salgueiro@ipma.pt;
fatima.abrantes@ipma.pt

https://doi.org/10.58998/jnr3271
The Iberian margin, a climate-sensitive region that is susceptible to global warming effects and alterations in watersupply, experiences seasonal wind-driven upwelling and belongs to the productive Canary Current Upwelling System.
These systems hold significant importance for climate regulation and fishing but may face varying regional impacts due
to climate change as predicted by the Intergovernmental Panel on Climate Change (IPCC). Efforts have been made tocomprehend the variability of climate and marine ecosystem response to environmental changes in the Iberian margin
during Late Pleistocene, specifically using microfossil assemblages that are preserved within the sediments. However,uncertainties persist regarding the potential influence of ongoing warming on primary production along the Portuguese
continental margin.
To shed light on this issue and enhance predictions of future responses to environmental change, we reconstructed
the variability in primary production over the past millennium through a detailed analysis of nannofossil assemblages
that are preserved across different settings on the Portuguese continental shelf. Another objective was to distinguish between increased primary production caused by upwelling or river-derived nutrients. To create the coccolithophore timeseries, we employed sediment cores from offshore the Douro and Tagus Rivers and off Faro in the Algarve (Portugal).
Preliminary findings reveal relatively similar coccolith assemblages at the Douro and Tagus sites that are predominantly
composed of Emiliania huxleyi, Gephyrocapsa muellerae, Gephyrocapsa oceanica, and small Gephyrocapsa spp. The
Faro site, outside of the upwelling influence, displayed a warmer assemblage with a greater number of reworked coccoliths. Moreover, our data unveiled significant fluctuations in abundance and composition of coccolith assemblages
that can be linked to environmental changes at the study sites over time. The reconstruction of the response of key
phytoplankton assemblages that are documented herein is anticipated to enhance projections of the eastern boundary
upwelling system’s response to environmental variability for upcoming decades.

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Response of the coccolithophore Calcidiscus leptoporus toenvironmental change during the industrial era in the Subantarctic Southern Ocean
Andrés S. Rigual Hernández

Universidad de Salamanca, Área de Paleontología, Departamento de Geología, 37008 Salamanca, Spain; arigual@usal.es

Gerald Langer

Autonomous University of Barcelona, ICTA, E-08193 Bellaterra, Barcelona, Spain; gerald.langer@cantab.net

Francisco J. Sierro

Universidad de Salamanca, Área de Paleontología, Departamento de Geología, 37008 Salamanca, Spain; sierro@usal.es

Helen Bostock

University of Queensland, School of Earth and Environmental Sciences, Brisbane, Queensland 4072, Australia; h.bostock@uq.edu.au

Juan Manuel Sánchez-Santos

Universidad de Salamanca, Departamento de Estadística, 37008 Salamanca, Spain; jose@usal.es

Scott N. Nodder

National Institute of Water and Atmospheric Research, Wellington 6021, New Zealand; Scott.Nodder@niwa.co.nz

Tom W. Trull

CSIRO Oceans and Atmosphere, Hobart, Tasmania 7001, Australia; University of Tasmania, Australian Antarctic Program Partnership, Institute ofMarine and Antarctic Studies, Hobart, Tasmania 7001, Australia; Tom.Trull@csiro.auAndrew D. Moy

Australian Antarctic Division, Channel Highway, Kingston, Tasmania 7050, Australia; Andrew.Moy@aad.gov.au

Ruth Eriksen

University of Tasmania, Institute for Marine and Antarctic Studies, Hobart, Tasmania 7001, Australia; Ruth.Eriksen@csiro.au

José Abel Flores

Universidad de Salamanca, Área de Paleontología, Departamento de Geología, 37008 Salamanca, Spain; flores@usal.es

https://doi.org/10.58998/jnr3272
The Southern Ocean plays a vital role in global thermohaline circulation and serves as a significant sink for anthropogenic CO2. However, the physical and chemical properties of its surface waters are undergoing rapid and unrelenting
transformation. The rate of warming in Southern Ocean waters surpasses that of the overall ocean, and increased CO2
absorption leads to reduced pH levels and decreased carbonate ion concentration, a phenomenon known as ocean acidification. This significant change in marine water characteristics poses a serious threat to general marine ecosystems andparticularly to calcifying marine organisms.
Coccolithophores are the most abundant group of marine calcifying phytoplankton, and they are substantial contributors to pelagic production of particulate organic and inorganic carbon. Satellite observations suggest that extensive
coccolithophore blooms develop in the Subantarctic circumpolar zone during the austral summer. Therefore, alterations
in coccolithophore composition and calcification may have crucial implications for Southern Ocean marine ecosystems
and ocean chemistry, ultimately affecting climate change. In this study, we compared the morphometric features of thecoccoliths produced by Calcidiscus leptoporus across different time scales. Specifically, we analyzed coccolith occurrences that spanned the Holocene Epoch during an annual cycle by making sediment trap collections of underlying
sediments and obtaining a sediment core. Our findings indicate that the variability of some morphological parametersof C. leptoporus coccoliths has a significant correlation with changes in carbonate chemistry. Extrapolation of our observations suggests that a future reduction in cell and coccolith size will have a negative impact on the efficiency of thebiological pump in the Southern Ocean through a reduction of carbonate ballasting.

INA19Pleistocene–Holocene
calcareous
foraminifera from the Argentine
southwest Atlantic Ocean

101

nannofossils
andContinental Margin,

Lucía Rivas

YPF Tecnología, Berisso, Buenos Aires, Argentina; lucia.rivas@ypftecnologia.com

María Luciana Hiriart, Carlos Daniel Cuciniello, Jens Michael Thissen

YPF Tecnología, Berisso, Buenos Aires, Argentina; maría.l.hiriart@ypftecnologia.com; carlos.cuciniello@ypftecnologia.com; jensthissen@mail.de

https://doi.org/10.58998/jnr3273
As part of the “Pampa Azul Initiative”, a national program aimed at promoting ocean science research in Argentina, several sediment cores were obtained during the YTEC-GTGM 5 cruise in 2022 aboard the R/V Austral. Calcareous nannofossils and foraminiferal assemblages were analyzed in 14 samples recovered from two gravity cores taken on the slopeof the Argentine Continental Margin. Both cores contain abundant foraminifera and calcareous nannofossils but also
show evident signs of reworking. In the gravity core AU_GEO05_GCA (478 cm; water depth 1865 m), calcareous nannofossil assemblages are characterized by the dominance and high abundance of Emiliania huxleyi, followed by Gephyrocapsa muellerae, Gephyrocapsa oceanica, and Gephyrocapsa spp. small. Foraminiferal assemblages are composedof planktonic species that include Globoconella inflata (d´Orbigny, 1839), Globigerina bulloides (d´Orbigny, 1826),
Globorotalia truncatulinoides (d´Orbigny, 1839), and Globorotalia hirsuta (d´Orbigny, 1839). They are accompanied
by, in a much lower abundance, benthic foraminiferal species that include Cibicidoides spp. (Thalmann, 1939), Lobatula
wuellerstorfi (Schwager, 1866), and Pullenia bulloides (d'Orbigny, 1846). Towards the base of the core, a decrease innannofossil and benthic foraminiferal abundances was recorded, together with an increase in reworked calcareous nannofossils (Reticulofenestra spp.), radiolarians, and silicoflagellates. According to the dominance of Emiliania huxleyi inall samples, we interpreted a Late Pleistocene–Holocene age (Subzone NN21b).
Gravity core AU_GEO05_GCB (631 cm; water depth 2375 m) was divided into two sections based on the microfossil assemblages. The lower section (570–275 cm) contains a nannofossil assemblage dominated by G. muellerae and G.
oceanica. The most abundant foraminiferal taxa are G. inflata and G. bulloides. In the overlying section (187–8 cm),the nannofossil assemblage is composed of E. huxleyi with Gephyrocapsa spp. as accompanying taxa. With regard toforaminifera, G. inflata and G. bulloides have the highest abundances, but an increase in Neogloboquadrina pachyderma(Ehrenberg, 1861) and Neogloboquadrina incompta (Cifelli, 1961) was observed. Although reworked specimens wererecognized in all samples, at 275 cm, the highest abundance of Reticulofenestra sp. specimens was recovered. Calcareous nannofossil assemblages allowed us to assign a Middle Pleistocene age (Zone NN20) to the lower section, and a
Late Pleistocene–Holocene age (Subzone NN21b) to the upper section. Although the cores were collected from neareach other at similar depths and having similar thicknesses, it is interesting to highlight the differences in the ages of
their lower sections.

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Calcareous nannofossils from the Paleocene–Eocene
Thermal Maximum, IODP Site U1557, South Atlantic Ocean
Claire M. Routledge

Christian-Albrechts-University of Kiel, Institute of Geosciences, Kiel, Germany; claire.routledge@ifg.uni-kiel.de

Chiara Borrelli

University of Rochester, Department of Earth & Environmental Sciences, Rochester, NY, 14627, USA; cborrelli@ur.rochester.edu

Christopher M. Lowery

University of Texas at Austin, Institute for Geophysics, Austen, TX, 78712, USA; cmlowery@utexas.edu

Andrew J. McIntyre

University of Leicester, School of Geography, Geology and the Environment, Leicester, UK; am1422@leicester.ac.uk

https://doi.org/10.58998/jnr3274
Calcareous nannoplankton are the most abundant calcifying organisms in the modern ocean. They are widespread andevolve rapidly, making them ideal for assessing biotic changes during periods of transient climate change. The Paleocene–Eocene Thermal Maximum (PETM, ~56 Ma) was an abrupt and dramatic global warming event that resulted
from huge amounts of isotopically light carbon being released into the atmosphere, and which had profound effects on
the biosphere. The PETM is also considered to be a partial analog to modern rates of greenhouse gas emissions. Here,
we utilize material from a newly recovered PETM section from International Ocean Discovery Program (IODP) Site
U1557, the first such record from the western South Atlantic. Initially identified by a distinct layer of reddish-brown clay
with a significant increase in magnetic susceptibility, species of Rhomboaster that are restricted to the PETM interval
have also been identified.
Across the PETM interval at Site U1557, sedimentation rates are extremely high (11.53 cm/kyr; normal pelagic
sedimentation rates are generally <1 cm/ky), and total organic carbon values are also unusually high, indicating highoverall surface water productivity at that time. Nannofossil analyses show a relatively well-preserved and diverse assemblage with the presence of the PETM-specific taxa Rhomboaster calcitrapa and Rhomboaster cuspis, although forms of
the Discoaster araneus group are noticeably absent. Instead, we record slightly deformed specimens of the Discoastermultiradiatus group across this interval. This new record from the western South Atlantic will be compared with other
South Atlantic records from Walvis Ridge, Maud Rise, and Agulhas Plateau to improve our understanding of surface
water conditions and the relationship between plankton and climate during a period of extreme environmental stresswhere few records exist.

INA19103

Evaluating Oligocene calcareous nannoplankton diversity
and community dynamics
Claire M. Routledge

Christian-Albrechts-University of Kiel, Institute of Geosciences, Kiel, Germany; claire.routledge@ifg.uni-kiel.dePaul Bown

Department of Earth Sciences, University College London, London, UK; p.bown@ucl.ac.uk

Jeremy Young

Department of Earth Sciences, University College London, London, UK; jeremy.young@ucl.ac.uk

https://doi.org/10.58998/jnr3275
The Oligocene (33.9–23.03 Ma) remains a relatively understudied interval, yet it is bookmarked by two large glaciations
signifying the development of a continental-sized ice sheet on Antarctica (Eocene/Oligocene boundary at 33.9 Ma) andthe expansion of the ice sheet (Oligocene/Miocene boundary at 23.03 Ma). The lack of high-resolution, long-term records has hampered efforts to document the structure of biotic change through the Oligocene, a time of significant oceanand climate reorganization as the Earth system switched from the warm climates of the Paleogene to the cooler world of
the Oligocene and initiation of glacial–interglacial cycles.
Here we present long-term, high-resolution community records of nannoplankton assemblages from the early Oligocene to Early Miocene (31.89–21.77 Ma) obtained from Integrated Ocean Drilling Program (IODP) Sites U1406 andU1411 in the northwest Atlantic Ocean. We document the evolutionary history and community dynamics of calcareous
nannoplankton throughout this time to investigate the drivers behind the decline in diversity following the Eocene peak
and to analyze population restructuring associated with the emergence of key extant coccolithophore groups that constitute the foundation of modern phytoplankton communities. Generating these long-term records is crucial for understanding the background-level dynamics, and they are essential for accurately gauging the scale and impact of transient
climatic events (i.e., Eocene/Oligocene and Oligocene/Miocene boundaries).

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Application of nannofossils (the missing piece of the
puzzle) from offshore Newfoundland: Upgrading theregional stratigraphy via an integrated multidisciplinary
approachDavid Rutledge

PetroStrat Ltd., Tan-y-Graig, Parc Caer Seion, Conwy, Wales, LL32 8FA, UK; david.rutledge@petrostrat.com

https://doi.org/10.58998/jnr3276
The Atlantic margin of Canada has a long, >50-year history of oil and gas exploration that is comparable with the North
Sea. The province of Newfoundland and Labrador, whose continental shelf covers more area than the North Sea, has
had 529 wells drilled, five that have produced oilfields in the offshore Jeanne d’Arc Basin (Hibernia, Terra Nova, White
Rose, North Amethyst, and Hebron). There also have been major discoveries further offshore in the deep-water Flemish Pass Basin that have not yet been developed (e.g., Bay du Nord). In Newfoundland, oil and gas production becamea mainstay economic activity during the 1980s, effectively replacing cod fishing after the collapse of the Grand Banks
fishery industry. This investment in drilling led to intensive biostratigraphic work, which focused on palynology andforaminifera. There was limited or no use of nannofossils, the study of which was in its relative infancy during the
1980s. In the prolific Jeanne d’Arc Basin, where attention was focused on strata dated to the Early Cretaceous and Late
Jurassic, local lithostratigraphic schemes were age calibrated using palynology, which remained the go-to discipline
until recently. Key wells were often reanalyzed several times for palynology and foraminifera to resolve anomalies,
sometimes by the same contractor. Unfortunately, this resulted in many contradictory interpretations and a large volume
of biostratigraphic “baggage” with some age interpretations possibly based on lithostratigraphy alone.
Around 2010, exploration extended into deeper waters, and there was increased emphasis on nannopaleontology.
Nannofossils were utilized successfully at wellsites for real-time monitoring of deep-water exploration wells in the Laurentian Basin (Middle Jurassic to Middle Miocene) and Orphan Basin (Late Jurassic to Oligocene). Comparison of these
new nannofossil data with historical biostratigraphic data (then publicly available) indicated that there was a substantial
need for improving resolution and certainty in wells where nannofossils either had not been used or only a handful ofsamples were analyzed for nannofossils. This realization spawned a series of non-exclusive studies focusing on the frontier exploration basins where there was a need to maximize information gleaned from limited well penetrations. Thesestudies covered the Orphan Basin (10 wells), Flemish Pass (16 wells), Carson Basin (9 wells), and Southern Flemish
Pass into Jeanne d’Arc Basin (16 wells). Other key wells to the south of Newfoundland were examined for research anddevelopment. The main goal of these studies was to integrate palynology, micropaleontology, and nannopaleontology
data to improve biostratigraphic resolution and its accuracy. New analyses were biased towards nannofossils, the missing piece of the puzzle. This integrated approach helped resolve many ambiguities and restore confidence in biostratigraphy, and it has been applied successfully during recent exploration campaigns.
Here I present a brief overview of available nannofossil data that show the variations in recovery/diversity throughtime and across the offshore basins, from the onset of normal marine conditions in the Early Jurassic (Pliensbachian) to
the Miocene. Historically, the main exploration prospects were Late Jurassic or Early Cretaceous in age, but economic
interest has widened to include the Paleogene. All presented information consists of non-proprietary data that were generated during PetroStrat’s non-exclusive studies or in-house research.

INA19105

Particulate inorganic carbon in the Pacific sector of
the Southern Ocean: Satellite measurements versus
coccolithophore estimates
Mariem Saavedra-Pellitero

University of Portsmouth, School of the Environment, Geography and Geosciences, Portsmouth, PO1 3QL, UK;mariem.saavedra-pellitero@port.ac.uk

Karl-Heinz Baumann

University of Bremen, Department of Geosciences, 28334, Bremen, Germany; baumann@uni-bremen.de

Nuria Bachiller-Jareno, Harold Lovell

University of Portsmouth, School of the Environment, Geography and Geosciences, Portsmouth, PO1 3QL, UK; nuria.bachiller-jareno@port.ac.uk;
harold.lovell@port.ac.uk

Nele Manon Vollmar

NORCE Norwegian Research Centre AS, NORCE Climate & Environment, 5007, Bergen, Norway; Bjerknes Centre for 9 Climate Research,
Bergen, Norway; nevo@norceresearch.no

Elisa Malinverno

Milano-Bicocca University, Department of Geological Sciences and Geotechnologies, 20126, Milan, Italy; elisa.malinverno@unimib.it

https://doi.org/10.58998/jnr3277
We have compared particulate inorganic carbon (PIC) derived from satellite data to in situ coccolithophore-based estimates in two latitudinal transects of the Pacific sector of the Southern Ocean (separated in time and space) in non-bloom
conditions. In situ and satellite-derived PIC show good agreement in the Subantarctic and Polar Front zones in bothtransects, but they differ to the south of the Polar Front. We attribute this mismatch to the high abundance of small opal
particles in the Antarctic zone. Gephyrocapsa huxleyi (also known as Emiliania huxleyi) is the dominant species in the
study area and almost the only species found in the southern part of both transects south of the Subantarctic Front. Using
morphometric analyses, we found that different morphotypes of this species, i.e., type A (morphogroup A) and types
B, B/C-C, and O (morphogroup B), show only minor latitudinal differences in size, mass, and degree of calcification. It
is mainly the dominant morphogroup B that contributes to the coccolithophore PIC content in surface waters. Satellite
products are an invaluable tool to estimate global PIC, but these should be combined with field samples whenever possible to validate remote sensing-derived PIC.

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Unusual calcareous nannofossil assemblages from the
Cenomanian–Turonian(93.9Ma)of
North
America:
Implications for nannofloral response to Oceanic Anoxic
Event 2
Jon Schueth

University of Nebraska Omaha, Department of Geography/Geology, Omaha, NE, 68182 USA; jschueth@unomaha.edu

Ursula Ziebolz

University of Nebraska Omaha, Department of Geography/Geology, Omaha, NE, 68182 USA; uziebolz@unomaha.edu

Bruce Hart

University of Western Ontario, Department of Earth Sciences, London, ON, Canada; bhart7@uwo.ca

https://doi.org/10.58998/jnr3278
Oceanic Anoxic Event 2 (OAE2), a period of global marine anoxia and black shale deposition, took place across the
Cenomanian/Turonian boundary (CTB; 93.9 Ma). Biomarkers, along with many microfossil groups, indicate that there
was elevated paleoproductivity during OAE2. However, previous studies of calcareous nannofossils show a shift tooligotrophic assemblages, especially in Europe and North America. It is important to understand this apparent disconnect between nannofossil and other productivity proxies as it may provide insights into how modern nannoplankton will
respond to anthropogenically induced oceanographic changes such as elevated nutrient levels and loss of oxygen.
Here we describe the results of recent investigations of calcareous nannofossils from the CTB across the USA and
Canada. We used novel integrated statistical techniques that combine geochemical proxies with nannofossil assemblages to reinterpret the paleoecology. We also observed several taxa that are generally rare in, or absent from, other Upper
Cretaceous sections. Overall, the assemblages have high species richness, sometimes exceeding 60 species in a sample,
which is likely due to enhanced preservation from a high clay content. The statistical analysis and subsequent revisionin paleoecologic interpretations indicate that primary productivity may have been elevated in nannoplankton across the
CTB, in contrast to other studies. However, there is a notable spatial heterogeneity in the nannofloral assemblages thatlikely is related to local paleoenvironmental factors. It is possible that previous interpretations of nannofloral oligotrophy may reflect these small-scale heterogeneities.
We also suggest that such shallow shelf settings were centers of evolutionary innovation in the Late Cretaceous andacted as refugia from harsh marine environments, as they did after the mass extinction at the end of the Cretaceous. We
describe some rare and newly discovered taxa that have higher occurrences in these shallow shelf environments. We
note a rapid expansion of the nannoliths in Canada in the earliest Turonian and comment on the possible evolution of
the widespread Turonian nannolith genus Marthasterites. Overall, our results show the importance of focused studies ofCretaceous marginal marine environments as a way to gain a better understanding of the evolutionary history of calcareous nannoplankton and their response to global climate change.

INA19107

Calcareous nannofossils, Oceanic Anoxic Event 2, and the
Cenomanian/Turonian boundary in cores from eastern Louisiana, USA
Jean M. Self-Trail

U.S. Geological Survey, Florence Bascom Geoscience Center, Reston, VA 20192, USA; jstrail@usgs.gov

Celeste D. Lohr, William H. Craddock, Matthew D. Merrill

U.S. Geological Survey, Geology, Energy & Minerals Science Center, Reston, VA 20192, USA; clohr@usgs.gov; wcraddock@usgs.gov;
mmerrill@usgs.gov

https://doi.org/10.58998/jnr3279
Sediments of the Tuscaloosa Formation extend across the northern Gulf of Mexico basin and east of the Sabine uplift in
Texas and Louisiana. The sediments consist of three informal units: the lower Tuscaloosa, the Tuscaloosa marine shale,
and the upper Tuscaloosa. They are equivalent in age to the Woodbine Sandstone and Eagle Ford Shale in west Texas.
Collectively, these sediments are associated with the onset of sea-level rise during the early to late Cenomanian, withmaximum transgression during the late Cenomanian and into the early Turonian, and with a regression in the middle
Turonian.
Although extensive biostratigraphic analyses have been published on west and east Texas Cenomanian–Turonian
sections, very few biostratigraphic data exist from similarly aged sediments from eastern Louisiana. Here we examine
the calcareous nannofossil assemblages from spot cores in the Biloxi Marshlands P-2 and O-1 wells and compare themto assemblages from the updip Eads Poitevent core. The oldest spot cores are from Biloxi Marshlands P-2 and are early
Cenomanian (Zones UC1 and UC2, lower Tuscaloosa) to late Cenomanian (Zone UC3, Tuscaloosa marine shale) inage. The presence of Eiffellithus turriseiffelii and Corollithion kennedyi in the basal sample places the bottom of thecore in Zone UC1. The first occurrence of Broinsonia gammation (Zone UC2) is at 21,263.2 ft (6481.0 m), and the firstoccurrence of Lithraphidites acutus (base of Zone UC3) is at 21,253.2 ft (6477.9 m). Corollithion kennedyi is present
through the highest cored sample (20,110.0 ft), suggesting an age no younger than late Cenomanian. The cored intervalin the Biloxi Marshlands O-1 well is from the upper Tuscaloosa, is late Cenomanian to early Turonian in age, and it isassigned to Zones UC4–UC7. The last occurrence of Helenia chiastia at 19,411.8 ft (5916.7 m) marks the Cenomanian/Turonian boundary.
Examination of total organic carbon (TOC) and carbon isotope ratios of bulk organic carbon (δ13Corg) from the Biloxi
Marshlands O-1 well suggests that Oceanic Anoxic Event 2 (OAE2) is present from 19,413–19,407 ft (5917.0–5915.2
m). The base of the event was not cored, as evidenced by the fact that carbon isotopes are at their heaviest in the base of
the core. The TOC is at 4–5% throughout the OAE2 interval. Carbon isotope ratios shift more negatively from -23‰ to-25‰ above the Cenomanian/Turonian boundary. However, an unconformity is identified using biostratigraphy at theUC6a/UC7 zonal boundary, which indicates that the top of OAE2 is truncated. Preliminary comparison with the updip
Eads Poitevent core suggests that in eastern Louisiana, the carbon isotope excursion for OAE2 may not be isochronous,
and further work is needed to confirm this finding.

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Preliminary biostratigraphy of the lower Cenomanian Buda
Limestone from the U.S. Geological Survey GC-3 and GC-5
cores, Texas, USA
Jean M. Self-Trail

U.S. Geological Survey, Florence Bascom Geoscience Center, Reston, VA 20192, USA; jstrail@usgs.gov

Celeste D. Lohr

U.S. Geological Survey, Geology, Energy & Minerals Science Center, Reston, VA 20192, USA; clohr@usgs.gov

Jason A. Flaum

U.S. Geological Survey, Central Energy Resources Science Center, Denver, CO 80023, USA; jflaum@usgs.gov

https://doi.org/10.58998/jnr3280
The lower Cenomanian Buda Limestone is a widely occurring formation found across the Texas Gulf Coast Basin andextending across the state and into southeastern New Mexico and northern Mexico. In central Texas, it overlies the Albian Del Rio Formation at its base and is unconformably overlain by the Eagle Ford Group at the top. Thickness of the
Buda Limestone in central Texas typically ranges from 32.8–82.0 ft (10–25 m), except where it is absent along the apexof the San Marcos Arch (SMA) in the Austin area. The Buda Limestone was deposited in a shelf setting in the northern
Gulf of Mexico during transgressive flooding of the platform in a period when the gulf’s connection with the WesternInterior Seaway was disrupted.
As part of ongoing research on Gulf Coast (GC) Basin Cenomanian–Turonian sections drilled by the U.S. Geological Survey, calcareous nannofossil biostratigraphic analysis of the resultant GC-3 and GC-5 cores, extending from the
SMA to the eastern flank of the Maverick Basin, was performed. Calcareous nannofossil abundances are highly variablethroughout the sections. Samples taken from white, chalky limestone typically had lower species abundance than thosetaken from the gray, silty stringers that are interspersed throughout the Buda Limestone. The base of the Buda Limestone
in the GC-3 core at 331.5 ft (101.0 m) is considered to be earliest Cenomanian (Zone UC0) in age, based on (1) the last
occurrence of Crucicribrum anglicum in the underlying Del Rio Formation, (2) the common occurrence of Eiffelithus
turriseiffelli, and (3) the absence of any younger marker species. The last occurrence of Gartnerago gammation, whichis commonly thought to occur in the early Cenomanian before the base of Gartnerago segmentatum, is at 321.3 ft (97.9m) in GC-3 and may mark the top of Zone UC1. Corollithion kennedyi is absent throughout the Buda Limestone andonly has its first appearance in the overlying Eagle Ford Group, suggesting that the depositional environment of the
Buda Formation was not favorable for this species and thus making biostratigraphic analysis challenging. Nannoconus
spp., a group thought to have preferred marginal to neritic carbonate platforms, and Lithraphidites alatus are frequent
to common throughout the lower part of the Buda Limestone. The first occurrence of Lithraphidites acutus at 127.0 ft(38.7 m) in GC-3 is in the lower Eagle Ford Group and marks the base of Zone UC3.
Minor amounts of glauconite and pyrite are present in the basal Buda Limestone, and calcitic ooids are common, allof which increase in abundance up-section. Exceptionally low total organic carbon (TOC) values (<1%) are recorded
throughout. The presence of ooids, extremely low TOC, and common nannoconids, along with the lack of marker
species often associated with organic-rich shales, all corroborate that Buda Limestone deposition occurred in the early
Cenomanian on a flooded carbonate platform with little sedimentary influence from the proximal shoreline.

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Early to Middle Miocene nannofossils from the Valhall–Hodarea, Norwegian North Sea
Emma Sheldon

Geological Survey of Denmark and Greenland, Department of Geo-energy and Storage, DK 1350, Copenhagen K, Denmark; es@geus.dk

Karen Dybkjær

Geological Survey of Denmark and Greenland, Department of Geo-energy and Storage, DK 1350, Copenhagen K, Denmark; kd@geus.dk

Erik Skovbjerg Rasmussen

Geological Survey of Denmark and Greenland, Department of Geophysics and Sedimentary Basins, DK 1350, Copenhagen K, Denmark; esr@geus.dk

https://doi.org/10.58998/jnr3281
The siliceous–diatomite succession of the lower to middle Miocene is currently a focus in the Norwegian sector of theNorth Sea in the Valhall–Hod area, owing to its potential as a hydrocarbon reservoir. Cored sections from the Valhalland Hod fields together provide a unique, continuous record of the Aquitanian to Langhian succession of the Lark Formation (upper part of the Hordaland Group). The succession is equivalent to the recently established Dany and Nora
Formations in the Danish sector of the North Sea, which comprise gray to brown muds with diatom-rich intervals. A
high-resolution, multidisciplinary biostratigraphic study, including foraminifera, dinoflagellate cysts, diatoms, silicoflagellates, and calcareous nannofossils, has recently been carried out on the lower to middle Miocene succession in six
wells from the Valhall and Hod fields. The biostratigraphic framework resulting from the study of the two new coredwells, 2/11-12S (Hod field) and 2/8-G10A (Valhall field), was tested successfully on ditch cuttings samples from fourneighboring, non-cored wells: 2/8-N4, 2/8-V6, 2/8-8, and 2/11-1.
Biostratigraphic subdivision of the North Sea Miocene succession, using dinoflagellate cysts and microfossils (foraminifera, Bolboforma, and pyritized diatoms), has proven to be reliable in clays and marls, and recently siliceous diatoms
have been successfully applied to the siliceous intervals for biostratigraphic breakdown. Nannofossil biostratigraphy is
not conventionally used in the Miocene of the North Sea due to the success and effectiveness of other fossil groups andcomparatively long nannofossil zone ranges. However, a limited number of nannofossil samples, which were collectedfrom calcareous intervals in the six wells, contained nannofossil assemblages with varying abundance, diversity, andpreservation. The Valhall and Hod fields lower to middle Miocene sections span nannofossil Zones NN3–6. The nannofossil biostratigraphy supports that of the other microfossil disciplines in this study, supplementing the refined androbust biostratigraphic framework.
Useful nannofossil events, in stratigraphic order, that correlate across the Valhall–Hod area include the first occurrences (FOs) of Cyclicargolithus floridanus, Helicosphaera carteri, Helicosphaera ampliaperta, and Discoaster emblematicus and the last occurrences (LOs) of Discoaster caulifloris, D. emblematicus, Discoaster exilis, Helicosphaera
bipuncta, and C. floridanus. Nannofossil assemblages also include Helicosphaera bipuncta, Helicosphaera waltrans,
Helicosphaera walbersdorfensis, Reticulofenestra pseudoumbilicus, Sphenolithus apoxis, and Sphenolithus puniceus.
Early to middle Miocene sea surface temperature fluctuations are indicted by variations in the relative abundance patterns of Discoaster spp. and Sphenolithus spp. (warm affinity) and Reticulofenestra spp. (cool affinity), complementing
the microfossil and dinoflagellate cyst data.

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Biostratigraphy and the energy transition
Mike Simmons

Halliburton, 97 Milton Park, Abingdon, OX12 8FL, UK; The Natural History Museum, London, SW7 5BD, UK; mike.simmons@halliburton.com

https://doi.org/10.58998/jnr3282
The ongoing energy transition means that the subsurface has never been more in demand than it is today. In addition
to selective exploration for and exploitation of traditional resources, subsurface understanding is required to store CO2
and hydrogen, to locate critical minerals, for geothermal energy, and for engineering projects including wind turbine
location. Geoscientists are therefore required to predict and characterize the subsurface. This in turn requires an ability
to correlate rock units and determine their depositional setting to build the most plausible subsurface models possible.
Chronostratigraphically significant correlation and paleoenvironmental interpretation are the long-established strengthsof biostratigraphy, especially when integrated with techniques such as sedimentology, sequence stratigraphy, isotope
stratigraphy, and geophysics. Such applied biostratigraphy may be carried out as part of desktop studies or during operations, such as the drilling of a well.
Successful applied biostratigraphy is rooted in the detailed understanding of the fossils involved, including the agreed
identity of taxa (through taxonomic studies) and an understanding of stratigraphic ranges that ideally are calibrated tothe standard chronostratigraphic scale. Bioevents (e.g., the inception and extinction of taxa) can be recognized, placed inorder, and biozonation schemes developed, defined by these events and characterized by assemblages of taxa. To some,
this may seem old-fashioned science, but it remains essential. Misuse of taxonomic names and poor age calibration canlead to uncertain stratigraphic or paleoenvironmental ranges, diluting the power of the fossils involved. Calibration ofTuronian nannofossil bioevents and biozonation schemes is a case in point, and despite decades of research, agreementon the identity of the fossils and their ranges remains to be achieved. It may be that digital techniques such as machinelearning will prove useful in the quest for improvement in biostratigraphic understanding by accelerating identificationand interpretation procedures, but their success depends on a major effort of standardization in understanding identity
and range. In short, the time of the “stratigraphic atlas” of a particular fossil group has not yet passed!
It is essential that the value of applied biostratigraphy in the energy transition is understood, and not just by biostratigraphers, but by the geoscience community in general. Successful case studies and best practices need to be shared.
Moreover, a new generation of applied biostratigraphers is required to answer the subsurface challenges of the energy
transition. Provision of energy with minimal environmental impact is the greatest challenge humanity faces in the 21st
century if health, prosperity, and societal stability are to be maintained. This requires a major upgrade in the understanding of the subsurface that is supported by all aspects of geoscience, not least of which is biostratigraphy.

INA19111

Early Pliocene calcareous nannofossils contribute to thepaleoceanographic reconstruction of the Cretan Basin (southern Aegean Sea, NE Mediterranean)
Elisavet Skampa

National and Kapodistrian University of Athens, Faculty of Geology and Geoenvironment, Panepistimioupolis, 15784, Athens, Greece;
elskampa@geol.uoa.gr

Margarita D. Dimiza

National and Kapodistrian University of Athens, Faculty of Geology and Geoenvironment, Panepistimioupolis, 15784, Athens, Greece;
mdimiza@geol.uoa.gr

Agnieszka Arabas

Polish Academy of Sciences, Institute of Geological Sciences, Research Centre in Krakόw, Krakόw, 31-002, Poland; agnieszka.arabas@gmail.com

Alexandra Gogou

Hellenic Centre for Marine Research, Institute of Oceanography, 19013 Anavyssos, Greece; agogou@hcmr.gr

Ioannis P. Panagiotopoulos, Theodora Tsourou

National and Kapodistrian University of Athens, Faculty of Geology and Geoenvironment, Panepistimioupolis, 15784, Athens, Greece;
ioapanag@geol.uoa.gr; ttsourou@geol.uoa.gr

Dimitrios Velaoras

Hellenic Centre for Marine Research, Institute of Oceanography, 19013 Anavyssos, Greece; dvelaoras@hcmr.gr

Marios Karagiorgas

National and Kapodistrian University of Athens, Faculty of Geology and Geoenvironment, Panepistimioupolis, 15784, Athens, Greece;
mariosk3gmail.com

Karl-Heinz Baumann

University of Bremen, Department of Geosciences, 28334 Bremen, Germany; baumann@uni-bremen.de

Maria V. Triantaphyllou

National and Kapodistrian University of Athens, Faculty of Geology and Geoenvironment, Panepistimioupolis, 15784, Athens, Greece;
mtriant@geol.uoa.gr

https://doi.org/10.58998/jnr3283
A detailed investigation of calcareous nannofossil accumulation rates and hydroclimatic proxies in the Deep Sea Drilling Project (DSDP) Site 378 sediment record located in the Cretan Basin aims to improve our knowledge of the responseof the NE Mediterranean during the warm Early Pliocene (Skampa et al., 2024). The studied sequence has been dated
between ~5.2 and 3.9 Ma (i-cycles 490–374). The age of the first Zanclean marine sediments that overlie the Messinian
deposits demonstrates that the Cretan Basin was partially desiccated for at least ~400 kyr, reflecting the fact that it wasa shallow epicontinental area in the Late Miocene. This multiproxy study, including elemental concentrations and stable
isotope measurements, revealed intervals of warm surface waters and low-oxygen conditions on the seafloor that wereassociated with the orbitally driven occurrence of rhythmic sapropelic layers in the Early Pliocene. Between ~5.2 and
4.6 Ma, the sapropelic layers were characterized by an elevated abundance of Reticulofenestra spp. and Florisphaera
profunda, indicating increased productivity throughout the photic zone. The dominance of the former in the accumulation rates reflects adequate nutrient availability in the surface layers, which is most likely associated with increased
riverine runoff into the eastern Mediterranean. In addition, the moderate abundances of F. profunda, compared to in theLevantine Basin (Athanasiou et al., 2017), may suggest that the formation of Levantine Intermediate Water (LIW) was
not strong enough to reach the Cretan Basin at the beginning of the Pliocene. In the subsequent time interval of ~4.6–3.9
Ma, the increase in the middle photic zone of the productivity index Helicosphaera spp. and the salinity thriving taxon
Umbilicosphaera jafari in the sapropelic and intercalated marly layers, respectively, imply freshening and enhanced
middle photic zone productivity that was associated with an intensification of the saline and nutrient enriched LIW

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presence at intermediate water depths. The increase in LIW intrusion, combined with the complete restoration of north–south Aegean marine gateways, led to the establishment of a hydrographic system similar to the modern Aegean Sea.
Acknowledgements:

This research is cofinanced by Greece and the European Union (European Social Fund [ESF]) through the Operational
Programme «Human Resources Development, Education and Lifelong Learning» in the context of the project “Strengthening Human Resources Research Potential via Doctorate Research – 2nd Cycle” (MIS-5000432), implemented by theState Scholarships Foundation (ІΚΥ) and by the Greek National Project CLIMPACT: Flagship Initiative for Climate
Change and its Impact by the Hellenic Network of Agencies for Climate Impact Mitigation and Adaptation.
References:
Athanasiou, M., Bouloubassi, I., Gogou, A., Klein, V., Dimiza, M.D., Parinos, C., Skampa, E. & Triantaphyllou, M.V. 2017. Sea surface temperaturesand environmental conditions during the “warm Pliocene” interval (~4.1–3.2 Ma) in the Eastern Mediterranean (Cyprus). Global and Planetary
Change, 150: 46–57. https://doi.org/10.1016/j.gloplacha.2017.01.008
Skampa, E., Dimiza, M.D., Arabas, A., Gogou, A., Panagiotopoulos, I.P., Tsourou, Th., Velaoras, D., Karagiorgas, M., Baumann, K.-H. & Triantaphyllou, M.V. 2024. The Cretan Basin (South Aegean Sea, NE Mediterranean) in the Early Pliocene: a paleoceanographic reconstruction.
Palaeogeography, Palaeoclimatology, Palaeoecology, 640: 112085. https://doi.org/10.1016/j.palaeo.2024.112085

INA19113

Responses of calcareous nannoplankton to mid-Pliocene
dynamics between climate and the carbon cycle in the North
Atlantic
Medhavi Srivastava

Charles University, Institute of Geology and Paleontology, Prague, Czech Republic; srivastme@natur.cuni.cz

Clara Bolton, Luc Beaufort, Thomas Chalk

Aix Marseille University, CNRS, IRD, INRAE, CEREGE, Aix en Provence, France; bolton@cerege.fr; beaufort@cerege.fr; chalk@cerege.fr

Paul Wilson

University of Southampton, Waterfront Campus, National Oceanography Centre, Southampton, UK.; paw2@soton.ac.uk

https://doi.org/10.58998/jnr3284
Calcareous nannoplankton, a vital component of marine ecosystems, serve as key players in the oceanic carbon cycle.
Thus, exploration of their population dynamics, biomass variations, and calcite content will provide insights into pastinteractions between climate and the carbon cycle. Using sediment samples from mid-latitude North Atlantic Integrated Ocean Drilling Program (IODP) Site U1313, we assess the calcareous nannofossil assemblage and calcification
response to major climate steps during a period of global warming under close-to-modern orbital and continental configurations (mid-Piacenzian Warm P eriod, ~3.3 to 2.9 Ma). Here, we present initial results from a total of 200 samples
spanning Marine Isotopic Stage (MIS) M2 to KM5c, a period encompassing an anomalously cold glacial stage within
the warm background climate of the Pliocene prior to the full-scale bipolar glaciation of the Pleistocene. This researchseeks to improve our understanding of how calcifying phytoplankton responded to mid-Pliocene “glacial–interglacial”
conditions and whether their productivity, calcite content, and/or morphology are linked to documented climate andpCO2 changes at or above modern values.
We used quantitative coccolith slide preparation techniques and AI microscopy (SYstème de Reconnaissance Automatique de COccolithes [SYRACO]) at CEREGE (Aix-en-Provence, France) to quantify changes in absolute andrelative abundances of nannofossil species, as well as coccolith morphology (size and mass). With these data, we calculated group-specific coccolith mass accumulation rates, as well as changes in morphological diversity index (MDI).
In combination with existing records spanning this interval, including many from Site U1313, this new calcareous nannofossil dataset will help us to understand coccolithophore productivity, calcification, and carbonate export responses
to climate and carbon cycle changes during the Pliocene, with implications for understanding the near future responses
of marine calcifiers.

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Nannofossil image searches using Scampi
Sissa Stefanowicz

Equinor ASA, Forusbeen 50, 4035 Stavanger, Norway; lsst@equinor.com

Roger Burgess

Equinor ASA, Sandsliveien 90, 5254 Sandsli, Norway; rdb@equinor.com

David Wade, Erik Anthonissen, Alex Cullum

Equinor ASA, Forusbeen 50, 4035 Stavanger, Norway; dawad@equinor.com; edant@equinor.com; cullum@equinor.com

https://doi.org/10.58998/jnr3285
It has been demonstrated that latent-space clustering of microfossil image embeddings can be leveraged to identify
meaningful groupings of microfossils (Martinsen et al., 2024). By extending this approach with a content-based image retrieval (CBIR) method, we have demonstrated a system called Scampi, which acts as a powerful search engine
tailored expressly for the needs of biostratigraphers (Wade et al., 2024). In our method, computer vision techniques can
automatically extract crops of all the individual microfossils from whole slide images on scanned slide preparations. An
arbitrary “query” image can then be compared to every single crop among the millions obtained from any given well,
promptly returning the most relevant matches for expert approval. This process may be repeated for multiple “queries”
of a known taxonomy, rapidly building up large numbers of expert-verified species identifications, significantly expediting the classification workflow. These observations can then be plotted by depth to produce the range charts familiar tobiostratigraphers. Additionally, our approach encourages uniform analyses across multiple wells, facilitating seamlesswell correlations that are integral for comprehensive geological assessments at field and regional scale. Crucially, efficiency does not come at the expense of reliability because the system is designed with a strong emphasis on auditability
and explainability, thereby maintaining high levels of confidence in species counts.
The analytical muscle of Scampi, powered by its sophisticated image processing algorithms, unlocks the potential
for innovative workflows that were formerly not feasible. Equinor has recognized the transformative capability of ourapproach and is integrating Scampi as a minimum viable product for palynology. We are now exploring the applicability
in the nannofossil domain with promising initial results (Figure 1). Scampi's heightened efficiency in analyses paves theway for a new era of speed and precision in microfossil identification and counting.
References:
Martinsen, I., Wade, D., Ricaud, B. & Godtliebsen, F. 2024. The 3-billion fossil question: How to automate classification of microfossils. Artificial
Intelligence in Geosciences, 5: 100080. https://doi.org/10.1016/j.aiig.2024.100080
Wade, D., Stefanowicz, S., Anthonissen, E. & Cullum, A. 2024. Species Classification Automation for Microfossil Photomicrograph Images (Scampi). 85th EAGE Annual Conference & Exhibition, volume 2024: 1–5. https://doi.org/10.3997/2214-4609.2024101100
Young, J.R., Bown, P.R. & Lees, J.A. 2024. Nannotax3 website. International Nannoplankton Association. Accessed 6 June 2024. URL: www.
mikrotax.org/Nannotax3

INA19Figure 1. t-SNE embedding of feature vectors generated from nannofossil images (Young et al., 2024), with illustrative examples displayed.

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Early
Eocenehyperthermals
innorthern
Bulgaria(SE Europe): New nannofossil and stable isotope data
Kristalina Stoykova

Bulgarian Academy of Sciences, Geological Institute, BG-1113 Sofia, Bulgaria; stoykova@geology.bas.bg

Marin Ivanov

Sofia University “St. Kl. Ohridski,” BG-1000 Sofia, Bulgaria; mivanov@gea.uni-sofia.bg

https://doi.org/10.58998/jnr3286
We present new calcareous nannofossil and benthic carbon and oxygen stable isotope records for a marl-rich, shallowwater succession of the Paleocene–Eocene transition that is exposed at three neighboring sections in central northern
Bulgaria (Pleven District). The presence of nannofossil Zones NP9, NP10, and NP11 is confirmed with high-resolution
nannofossil biostratigraphy. The carbon dissolution interval is marked by the abrupt drop of CaCO3 content and deposition of a clay interval at the onset of the Paleocene–Eocene Thermal Maximum (PETM). Stable isotope analysesof δ13C and δ18O were performed on benthic foraminiferal tests. The stepped carbon isotope excursion (CIE) profile
consists of three discrete intervals of decreasing carbon isotope values. An unusual two-fold CIE in the PETM interval
is documented with a total negative shift of 2.89‰. Moreover, three paired negative excursions are identified: two in
the uppermost Thanetian (upper Zone NP9 within the PETM interval) and one within the lower Eocene (Zone NP11).
The presence of a carbon dissolution interval in the uppermost part of the Paleocene is unequivocally supported by the
sedimentological study.
The most prominent negative carbon isotope excursion (4.90‰ negative shift) is observed within Zone NP11. It isrelated to the Eocene Thermal Maximum 3 (ETM 3) event (or “X” event), dated at 52.84 Ma ago. This hyperthermal
event preceded the Early Eocene Climatic Optimum (EECO), the interval with the hottest climate in Earth's Cenozoic
history. The paleotemperature data for the seawater, derived from δ18O values in benthic foraminiferal shells, ranged between 23.18°C and 35.73°C during the PETM and reached a maximum of 38.43°C during the ETM 3 event. In addition,
during the ETM 3 event the deposition of the mineral aragonite, characteristic of coastal settings with high evaporationand high seawater temperature, was recorded.
Acknowledgements:

This work has been carried out in the framework of the National Science Program "Environmental Protection andReduction of Risks of Adverse Events and Natural Disasters" and supported by the Ministry of Education and Science(MES) of Bulgaria (Agreement № Д01-27/06.02.2024).

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Calcareous nannofossil response to the early Oligocene
Rhodope volcanic eruptions in some central and eastern
Paratethyan basins: A comparison
Kristalina Stoykova

Bulgarian Academy of Sciences, Geological Institute, BG-1113 Sofia, Bulgaria; stoykova@geology.bas.bg

Peter Marchev, Raia Raicheva

Bulgarian Academy of Sciences, Geological Institute, BG-1113 Sofia, Bulgaria; pmarchev@geology.bas.bg; raya@geology.bas.bg

https://doi.org/10.58998/jnr3287
The aim of the present study is to evaluate the impact of two large early Oligocene Rhodope volcanic eruptions on themarine calcareous nannoflora across several central and eastern Paratethyan basins, including the Thrace Basin (Limnos
Island, Greece). The tuff layers from the Hungarian Paleogene Basin (Central Paratethys), Massignano, Umbria-Marche
Basin, Italy (western Mediterranean), eastern Carpathian Basin, Romania (Eastern Paratethys), western Black Sea Basin, Bulgaria (Eastern Paratethys), and Thrace Basin, Turkey and Limnos Island, Greece (Eastern Paratethys) have been
dated at 33.3 Ma ± 0.1 Myr and 32.7 Ma ± 0.1 Myr, perfectly matching the ages of two early Oligocene supereruptions
from the Borovitsa volcano in eastern Rhodope, Bulgaria. The calcareous nannoplankton response to the eruptions
was investigated using published data from these basins and our newly obtained quantitative data from Limnos Island(southernmost Thrace Basin). Our results from Limnos significantly differ from the published data from Central andEastern Paratethys localities, where volcanic eruptions and gradual cooling prompted a decline in species diversity andquantitative abundance and an increase in cold-water nannofossil taxa (e.g., in the Hungarian Paleogene Basin andthe pre-Carpathian Basin in Romania). In Limnos, nannofossil species diversity is high (64 taxa recorded), as well as
quantitative abundance in the assemblages. However, after each volcanic eruption, there was a resulting increase in thenumber of species considered eutrophic, such as Cyclicargolithus floridanus, Reticulofenestra bisecta, and Zygrhablithus bijugatus. This reflects an increase in primary productivity and reduced, but moderate, temperature of the seawater.
In conclusion, the documented response of the calcareous nannoplankton to early Oligocene Rhodope volcanic eruptions shows considerable differences across central and eastern Paratethys basins. In the small and more isolated basins(Hungarian, eastern Carpathian, and western Black Sea), the species diversity and quantitative abundance decrease,
whereas the number of cold-water taxa increases. In the deep-water environment of Limnos (Thrace Basin), nannofossil species diversity and quantitative abundance remain high, whereas assemblages are dominated by species preferringa temperate sea water temperature. We speculate that the connection between the Paratethyan isolated basins and theMediterranean Sea remained open during this time through the southernmost part of the Thrace Basin (Limnos Island).
Acknowledgements:

This work has been carried out in the framework of the National Science Program "Environmental Protection andReduction of Risks of Adverse Events and Natural Disasters" and supported by the Ministry of Education and Science(MES) of Bulgaria (Agreement № Д01-27/06.02.2024).

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Calcareous
nannofossilchangesinreddish-brown
sediments in the abyssal South China Sea during the
Oligocene–Miocene
Xiang SuSouth China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China; suxiang@scsio.ac.cn

Rong Xiang

South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China

Chuanlian Liu

Tongji University, State Key Laboratory of Marine Geology, Shanghai 200092, China

https://doi.org/10.58998/jnr3288
Oceanic red beds are unique pelagic sediments in the global ocean, providing excellent archives for understanding
chemical weathering and relevant climate change in their source areas. During International Ocean Discovery Program (IODP) Expedition 367/368/368X, a series of boreholes were drilled in the northern South China Sea (SCS). At
the abyssal Site U1499 (3758 m below sea level), successive core sections were recovered from 792 to 929 m below
seafloor. The most remarkable features in these cores are the consecutive occurrences of reddish-brown sediments.
Although calcareous microfossils were relatively sparse in some intervals due to poor preservation or low recovery,some key species, which were well preserved and present in most of the samples, were useful for age determinations.
Fifteen calcareous nannofossil datums were recognized through the studied interval, revealing a generally continuous
succession dated from the early Oligocene to the Late Miocene. By combining calcareous nannofossil and foraminiferal
biostratigraphic data, the development and evolution of the oceanic red beds in the northern SCS could be reconstructed.
The changes in nannofossil abundance and assemblage composition were mainly influenced by global sea level changes,
environmental factors, and regional tectonic events. These results imply that formation of the oceanic red beds probably
resulted from the extent of deepwater ventilation in the abyssal SCS. During the Middle Miocene, a short hiatus between
13.6 and 12.0 Ma correlated with an intensive sedimentation rate increase, which was the main reason that oceanic red
bed deposition ended.

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Multivariate evaluation rubric for assessing the reliabilityof Cretaceous nannofossil index taxa and bioevents
Deborah Tangunan

University College London, Department of Earth Sciences, London, UK; d.tangunan@ucl.ac.uk

Paul Bown

University College London, Department of Earth Sciences, London, UK; p.bown@ucl.ac.uk

Matt Hampton

Network Stratigraphic Consulting Limited, Potters Bar, Hertfordshire, UK; matt@network-stratigraphic.co.uk

Thomas Fogerty

The Natural History Museum, Cromwell Road, London, UK; thomas.fogerty@nhm.ac.uk

Andy Gale

University of Portsmouth, School of the Environment, Geography and Geological Sciences, Portsmouth, UK; andy.gale@port.ac.uk

Richard Twitchett

The Natural History Museum, Cromwell Road, London, UK; r.twitchett@nhm.ac.uk

Charles Underwood

University of London, Birkbeck, Bloomsbury, London, UK; ubfb050@mail.bbk.ac.uk

James Witts

The Natural History Museum, Cromwell Road, London, UK; james.witts1@nhm.ac.uk

Liam Gallagher

Network Stratigraphic Consulting Limited, Potters Bar, Hertfordshire, UK; liam@network-stratigraphic.co.uk

https://doi.org/10.58998/jnr3289
Calcareous nannofossils (nannoplankton) are essential in biostratigraphy because of their widespread distribution, dynamic evolution, distinct morphological characteristics, and sensitivity to environmental and climatic changes. As a key
tool in biostratigraphy, they offer crucial information about geologic strata by documenting the age of deposition andproviding insights on past environments and ecosystems. While the reliability of an index nannofossil taxon or bioevent
is a critical factor for accurate biostratigraphic interpretations, current approaches to assess reliability are primarily
qualitative, highlighting the need for a more standardized framework.
Here we discuss a multivariate quantitative evaluation rubric to address the complexities associated with assessing
the reliability of calcareous nannofossil bioevents. Using existing data and information sourced from published literatureand our own records from the Cretaceous chalk of southern England, this rubric combines a range of criteria including (1) taxonomic clarity and consistency, (2) morphological specificity and distinction, (3) geographical and temporal
distribution, (4) rarity and frequency, (5) preservation quality, (6) reliability and usefulness based on published literature, and (7) references and source validity. The development of these guidelines is based upon a thorough synthesisof biostratigraphic work done by the calcareous nannofossil community over the years, aiming to provide a standardized framework designed to strengthen consistency and accuracy in nannofossil-based biostratigraphic interpretations.
Furthermore, the use of this rubric extends beyond qualitative assessments by integrating multivariate analyses using
a quantitative ranking of various criteria that may be applicable to specific time scales or regions. These reliability test
guidelines thus allow for the determination of robust nannofossil index species and bioevents, mitigating potential interpretative ambiguities and discrepancies inherent within a stratigraphic record. This underscores its significance foradvancing biostratigraphic work within the calcareous nannofossil research community and beyond, ultimately benefiting both academic research and industrial applications.

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Investigating the size variability and coccolith mass of
Emiliania huxleyi in the Aegean Sea (NE Mediterranean):
20 years of evidence on modern assemblages compared to
the last two thousand years
Maria V. Triantaphyllou

National and Kapodistrian University of Athens, Faculty of Geology and Geoenvironment, Panepistimioupolis, 15784, Athens, Greece;
mtriant@geol.uoa.gr

Elisavet Skampa, Margarita D. Dimiza

National and Kapodistrian University of Athens, Faculty of Geology and Geoenvironment, Panepistimioupolis, 15784, Athens, Greece;
elskampa@geol.uoa.gr; mdimiza@geol.uoa.gr

Dimitrios Velaoras

Hellenic Centre for Marine Research, Institute of Oceanography, 19013 Anavyssos, Greece; dvelaoras@hcmr.gr

Patrick James Penales

National and Kapodistrian University of Athens, Faculty of Geology and Geoenvironment, Panepistimioupolis, 15784 Athens, Greece; Universityof Lille 1, Department of Earth Sciences, CitéScientifique, CEDEX, 59655 Villeneuve d’Ascq, France; pfpenales@up.edu.ph

Sofia Apsemidou, Rozanna-Tsantara Rossolatou

National and Kapodistrian University of Athens, Faculty of Geology and Geoenvironment, Panepistimioupolis, 15784, Athens, Greece;
apsemidou@geo.auth.gr; rozanna000@yahoo.com

Constantine Parinos, Alexandra Gogou

Hellenic Centre for Marine Research, Institute of Oceanography, 19013 Anavyssos, Greece; ksparinos@hcmr.gr; agogou@hcmr.gr

https://doi.org/10.58998/jnr3290
The Aegean Sea, particularly its northern sector, is a key area for understanding climate fluctuations due to its importance as a source of deep-water formation in and subsequent ventilation for the entire eastern Mediterranean. A high anthropogenic CO2 content, which can be detected at intermediate and deep layers of the North Aegean Sea, is considered
to reflect the effective transportation of the absorbed atmospheric CO2 from the surface to deeper waters due to densewater formation (Krassakopoulou et al., 2017).
Variability in the size and mass of Emiliania huxleyi from the Aegean Sea (measurements of ~5000 coccoliths)
has been studied in water and sediment trap samples collected during the last 20 years. Biometric analyses confirm aconsistent pattern of increase in size and calcification degree during winter/springtime with low sea surface temperatures (SST) and moderate productivity, as compared to summertime high temperatures and low productivity, which isconsistent with previous observations of Triantaphyllou et al. (2010). Interestingly, the interannual coccolith length(CL) estimate for the entire Aegean area, both on a seasonal and spatial basis, displays an overall decrease during the
20 years of the studied time interval, whereas relative tube width (RTW) values show a generally increasing tendency
that is directly associated with a similar pattern in the North Aegean. The estimated coccolith mass (Young et al., 2014)
has an overall constant pattern averaging 2.2 pg, although a difference between average values is observed between cold
(November–April: 3.2 pg) and warm (May–October: 2.1 pg) intervals. A decreasing tendency in the E. huxleyi coccolithmass (-0.6 pg), particularly during the cold season, is recorded in the North Aegean. During the warm months, only theNorth Aegean E. huxleyi coccoliths are featured by RTW and mass increases, although both parameters display consistently lower values with respect to the cold period (average mass: 3.5 pg in the cold vs. 1.5 pg in the warm months).

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Within a high resolution North Aegean Sea sediment record that spans the past 1500 years (Gogou et al., 2016), theE. huxleyi RTW indicates an overall increase since the beginning of the 19th century, which is similar to the modern biocalcification signal. Interestingly, the E. huxleyi coccolith mass in the Common Era is decreasing when compared to thecooler intervals of the Little Ice Age and the Late Antique Little Ice Age, which is in line with the expected acidification
impacts due to increase in SST and anthropogenic CO2 content in the Aegean water column.
Acknowledgements

We acknowledge support of this work by the Greek National Project CLIMPACT: Flagship Initiative for Climate
Change and its Impact by the Hellenic Network of Agencies for Climate Impact Mitigation and Adaptation.
References:
Gogou, A., Triantaphyllou, M., Xoplaki, E., Izdebski, A., Parinos, C., Dimiza, M., Bouloubassi, I., Luterbacher, J., Kouli, K., Martrat,
B., Toreti, A., Fleitmann, D., Rousakis, G., Kaberi, H., Athanasiou, M. & Lykousis, V. 2016. Climate variability and socio-environmental changes in the northern Aegean (NE Mediterranean) during the last 1500 years. Quaternary Science Reviews, 136: 209–228.
https://doi.org/10.1016/j.quascirev.2016.01.009
Krasakopoulou, E., Souvermezoglou, E. & Goyet, C. 2017. Carbonate system parameters and anthropogenic CO2 in the north Aegean Sea during
October 2013. Continental Shelf Research, 149: 69–81. https://doi.org/10.1016/j.csr.2017.04.002
Triantaphyllou, M., Dimiza, M., Krasakopoulou, E., Malinverno, E., Lianou, V. & Souvermezoglou, E. 2010. Seasonal variation in Emiliania huxleyi coccolith morphology and calcification in the Aegean Sea (Eastern Mediterranean). Geobios 43: 99–110.
https://doi.org/10.1016/j.geobios.2009.09.002
Young, J.R., Poulton, A.J. & Tyrrell, T. 2014. Morphology of Emiliania huxleyi coccoliths on the northwestern European shelf – is there an influenceof carbonate chemistry? Biogeosciences, 11: 4771–4782. https://doi.org/10.5194/bg-11-4771-2014

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Morphometric analyses of Eprolithus floralis from Oceanic
Anoxic Event 2 in the Eastbourne section
Edna Tungo

UNISINOS University, Instituto Tecnológico de Paleoceanografia e Mudanças Climáticas (itt Oceaneon), São Leopoldo, RS, 93022-000, Brazil;
ednatungo@gmail.com

Cinzia Bottini, Elisabetta Erba

Università degli Studi di Milano, Dipartimento di Scienze della Terra “Ardito Desio”, 20133 Milano, Italy; cinzia.bottini@unimi.it;
elisabetta.erba@unimi.it

Mauro Bruno, Gerson Fauth

UNISINOS University, Instituto Tecnológico de Paleoceanografia e Mudanças Climáticas (itt Oceaneon), São Leopoldo, RS, 93022-000, Brazil;
dbruno@unisinos.br; Gersonf@unisinos.br

https://doi.org/10.58998/jnr3291
Oceanic Anoxic Event 2 (OAE2) (Cenomanian/Turonian boundary interval, CTBI; ~94 Ma) is regarded as one of themost extreme paleoenvironmental stressors that is characterized by global warming, accelerated hydrological cycle,enhanced production and burial of organic matter, very high concentrations of volcanically produced CO2, and alteredchemistry and structure of the oceans. During OAE2, calcareous nannoplankton were forced to face anomalous oceanographic and climatic conditions that induced both extinctions and originations, as well as changes in abundance andcalcification patterns. Previous studies documented fluctuations in the size of a few taxa and specifically “dwarfism” of
Biscutum constans at the core of the OAE2 perturbation.
The Eastbourne section is one of the reference records of OAE2 because of its completeness and high-resolution
chronostratigraphic framework. This section has one of the thickest CTBI records in the Anglo-Paris Basin and consistsof epicontinental pelagic deposits of the English Chalk. A large, high-resolution, multiproxy dataset reveals an intervalof cooling, a phenomenon known as the Plenus Cold Event, during OAE2. We performed abundance and morphometricanalyses of Eprolithus floralis on 44 samples from the Eastbourne section to assess its adaptation to varying paleotemperatures and ocean chemistry, particularly at the onset of OAE2, across the Plenus Cold Event, and during the recovery
phase after OAE2.
The results show an increase in relative abundance of E. floralis from the base section, reaching highest values
within the OAE2 stratigraphic interval, and decreasing after it. Morphometric analyses revealed larger total diameterand dominance of specimens with rays with a spiky outline before and after OAE2, whereas within OAE2, specimens
with smaller total diameter and rays with a rounded outline are dominant (~70%). The diaphragm average diametershows relatively lower values before and after OAE2, whereas larger dimensions are registered during OAE2, except
for the chemostratigraphic peak B, which is characterized by E. floralis specimens with the smallest diaphragm diameterof the section. The total diameter displays an ~7% and 10% reduction within OAE2 relative to the intervals preceding
and following the perturbation, respectively. Conversely, the diaphragm increases by ~1.3% during OAE2, although aminimum occurs during the chemostratigraphic peak B coeval with the total diameter minimum.
Our findings indicate that although E. floralis is usually interpreted as a cold-water species, its abundance and morphometric fluctuations are unrelated to temperature fluctuations across OAE2. It is worth noting that the size fluctuations of E. floralis can be correlated with those documented for B. constans and, in particular, a synchronous minimum
size is detected for both taxa in correspondence to the chemostratigraphic peak B, which is considered the interval of
greatest environmental disturbance. This similarity suggests that the main environmental stressors affecting B. constanssize during the early phase of OAE2 also influenced E. floralis morphometry.

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Evolutionary change in crystallographic orientation andmorphology of Cenozoic coccoliths: Insights from Toweius,
Reticulofenestra, and Umbilicosphaera
Masayuki Utsunomiya

Geological Survey of Japan, AIST, Tsukuba 305-8567, Japan; m.utsunomiya@aist.go.jp

Toshihiro Kogure

The University of Tokyo, Department of Earth and Planetary Science, Bunkyo-ku, Tokyo 113-0033, Japan; kogure@eps.s.u-tokyo.ac.jp

Kyoko Hagino

Kochi University, Marine Core Research Institute, Nankoku, Kochi 783-8502, Japan; hagino@kochi-u.ac.jp

Jean M. Self-Trail

U.S. Geological Survey, Florence Bascom Geoscience Center, Reston, VA, 20192, USA; jstrail@usgs.gov

https://doi.org/10.58998/jnr3292
The interlocking crystal units that form heterococcoliths have two different crystal orientations: near-vertical c-axis(V-unit) and near-horizontal c-axis (R-unit) (Young et al., 1992). The taxonomy of coccolithophores and V/R composition is consistent, suggesting that the crystallographic orientation in coccoliths has a common phylogenetic origin.
Comparison of crystallographic orientation among closely related species and between families and genera should
show how crystallography contributed to differences in morphology during the evolutionary process. We measured
crystallographic orientations of the genera Umbilicosphaera (Miocene–Pleistocene), Reticulofenestra (Miocene), andToweius (Eocene). The top of the coccolith surface was analyzed using scanning electron microscopy (SEM) and electron back-scattered diffraction (EBSD). If the shield surface was too steep for the electron beam to hit it, as was the casefor Toweius spp., a cross section of the coccolith was prepared with focused ion beam (FIB) sectioning and analyzed
using transmission electron microscopy (TEM). The crystallographic orientation of the distal shield of Reticulofenestra
was not found to be significantly different from that of the closely related extant genera Emiliania and Gephyrocapsa,
with the c-axis inclined 20°–30° toward the central opening. Toweius has two distinct crystal units showing different
c-axis directions. The crystallographic orientation of the elements forming the proximal shield and inner cycle of the
distal shield was closer to the R-units of Reticulofenestra, whereas the c-axis of the outer cycle element of the distal
shield seems to be the V-unit. This suggests that evolution from Toweius to Reticulofenestra was accompanied by loss or
miniaturization of the V-unit. The Umbilicosphaera lineage shows species-specific differences (e.g., element morphology, presence of bridge, etc.) due to subtle changes in crystallographic orientation and element growth direction (~10°in c-axis) (Utsunomiya & Kogure, 2024), but crystallographic orientations of their V- and R-units are clearly different
from those of Toweius and Reticulofenestra. Therefore, crystallographic orientation is considered to have changed withthe evolution of the coccolithophores.
References:
Utsunomiya, M. & Kogure, T. 2024. Evolutionary change of crystallographic orientation and coccolith morphology: Neogene–Quaternary Umbilicosphaera (Prymnesiophyceae) lineage. Marine Micropaleontology, 190: 102370. https://doi.org/j.marmicro.2024.102370
Young, J.R., Didymus, J.M., Bown, P.R., Prins, B. & Mann, S. 1992. Crystal assembly and phylogenetic evolution in heterococcoliths. Nature, 356:
516–518. https://doi.org/10.1038/356516a0

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Paleocene–Eocene calcareous nannofossil biostratigraphyof the Surprise Hill core from Virginia, USA
Masayuki Utsunomiya

Geological Survey of Japan, AIST, Tsukuba 305-8567, Japan; m.utsunomiya@aist.go.jp

Jean M. Self-Trail

U.S. Geological Survey, Florence Bascom Geoscience Center, Reston, VA, 20192, USA; jstrail@usgs.gov

D. Clay Kelly

University of Wisconsin-Madison, Department of Geology and Geophysics, Madison, Wisconsin, USA; ckelly@geology.wisc.edu

Xiaodong Zhang

University of California Santa Cruz, Department of Earth and Planetary Sciences, Santa Cruz, CA, USA; xzhan335@ucsc.edu

https://doi.org/10.58998/jnr3293
We present the lithology and calcareous nannofossil biostratigraphy of the Surprise Hill core, which was drilled in the
Salisbury Embayment in Northumberland County, Virginia, USA. The sedimentary record begins in the early Danianand includes a robust Paleocene–Eocene Thermal Maximum (PETM) section up through the Early Eocene Climatic
Optimum (EECO). We identified calcareous nannofossil datums that include the first occurrence (FO) of Heliolithus
cantabriae (59.60 Ma) in the Brightseat Formation, the FO of Discoaster multiradiatus (56.01 Ma) in the upper Aquia
Formation, the FOs of Discoaster salisburgensis var. anartios and Rhomboaster spp. (54.99 Ma) in the lower Marlboro
Clay, and the FOs of Tribrachiatus orthostylus (53.67 Ma) and Discoaster lodoensis (52.64 Ma), the last occurrence(LO) of T. orthostylus (50.66 Ma), the FO of Discoaster sublodoensis with five rays (48.96 Ma), and the LO of D. lodoensis (48.37 Ma) in the Nanjemoy Formation. An unconformity is present at 208.8 m that marks the contact between
the Danian Brightseat Formation below and the Selandian through Thanetian Aquia Formation above.
The abundance of Chiasmolithus bidens decreased precipitously just before the PETM, and this was also documented in the South Dover Bridge (SDB) core in Maryland and in the tropical Atlantic from Ocean Drilling Program(ODP) Hole 1259B. Additionally, Hornibrookina arca, whose abundance is usually <5%, increased to ~40% in the
Aquia Formation just prior to the PETM. A similar increase was also documented in three other cores in Maryland. The
carbon isotope excursion (CIE) of the PETM was identified from analyses of benthic foraminifera and is accompanied
by a change in the nannofossil assemblage, with C. bidens and H. arca being almost absent. A dissolution zone (85 cm
thick) was recognized in the basal Marlboro Clay, which is consistent with global patterns of dissolution at the PETM
onset. During the PETM, the genus Toweius shows little change in relative abundance, but there is a clear change in
species composition within the genus, and Toweius serotinus replaces T. tovae and T. eminens as the dominant species. In
the recovery phase of the PETM, T. tovae and T. eminens are replaced by T. callosus and T. occultatus, which is similar
to what was found in the SDB core. The abundance of the genus Reticulofenestra increases gradually through the interval, and the Toweius–Reticulofenestra turnover occurs just after the FO of Discoaster lodoensis, which marks the baseof Zone NP12. The calcareous nannofossil assemblage data from the Surprise Hill core provide a better understandingof the biotic response to paleoenvironmental changes on the continental shelf from the late Paleocene to early Eocene.

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CretaceousandCenozoic
calcareous
nannofossil
biostratigraphy of the northwestern inland basins of Colombia
Felipe Vallejo-Hincapié

Instituto de Investigaciones en Estratigrafía (IIES), Grupo de Investigación en Estratigrafía y Vulcanología (GIEV-Cumanday); Universidad deCaldas, Departamento de Ciencias Geológicas, Manizales, 1700004, Colombia; diego.vallejo@ucaldas.edu.cohttps://doi.org/10.58998/jnr3294
Calcareous nannofossils, one of the most valuable micropaleontological groups for dating and correlating Mesozoic
and Cenozoic oceanic deposits, have been little documented in onshore deposits of South America. We present here asummary of ten years of micropaleontological research on calcareous nannofossils in the northwestern inland basinsof Colombia that establishes a biostratigraphic framework for Colombian onshore deposits. Our study is based on theanalysis of 2444 samples from 88 onshore deposits across the Caribbean, Pacific, and inter-Andean valley basins. The
analysis reveals that calcareous nannofossils were identified in 57% of the analyzed samples, exhibiting moderate topoor preservation and common to rare abundance. We identified fourteen micropaleontological assemblages, which
include nannofossil markers used in the standard biozonations for tropical and subtropical regions. This enables us toplace Colombian deposits within these well-dated biozonations, resulting in a chronostratigraphic framework spanningfrom the Aptian (Early Cretaceous) to the Calabrian–Chibanian (Pleistocene). These results are compared to previous
ages reported in the literature, demonstrating a good correspondence with foraminifera, palynomorphs, and ammonites.
This comparative analysis serves to corroborate the reliability of our independent framework for dating and correlating
Colombian deposits. Future work should focus on Pacific inland basins and Mesozoic onshore deposits to add additional
refinement to this chronostratigraphic framework, which is expected to contribute to the understanding of the geologic
evolution of oceanic seaways operating in the Mesozoic and Cenozoic between the eastern Pacific Ocean and the protoCaribbean Sea.

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Challenges of optical properties of calcareous nannofossils
Osman Varol

Varol, Research, Rhos-on-Sea, North Wales, LL28 4AE, UK; osman@varol.com

https://doi.org/10.58998/jnr3295
Morphological features refer to changes in the external appearance and structural units of calcareous nannofossils. Thesefeatures are evident in their optical properties, which are crucial for identifying and classifying calcareous nannofossils
using a petrographic microscope under cross-polarized illumination. This identification process primarily depends on
the interaction of light with the atomic structure of the calcareous nannofossils. Fundamental optical properties used in
the identification and differentiation process include interference colors, retardation colors, extinction types (Figure 1),
and elongation direction.
Examining the bending directions (e.g., laevogyre or dextrogyre) of extinction lines in cross-polarized light andinterference color distribution (with the use of a gypsum plate) in cross-polarized light can significantly help to differentiate distal and proximal profiles of calcareous nannofossils. Applying optical properties to identify and classify
calcareous nannofossils presents several challenges due to their complex morphology and anisotropic nature. Calcareous
nannofossils are composed of calcite, an anisotropic uniaxial (-) crystal. Optical properties depend on orientation, so it
must be specified which profile the optical properties belong to (i.e., plan, distal, proximal, or side view). This study uses
a mobile mounting technique to reveal the optical properties at different orientations that can be used to identify taxa.

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Triquetrorhabdulus carinatus
EA = 0°

nɛ
nɯ

A

B

C

Orthorhabdus serratus
EA = 20°

nɯ
nɛ

D

F

E

Sphenolithus? furcatolithoides
EA

G

=4

5°

H

I

Figure 1. Illustration of extinction angle (EA) types for calcareous nannofossils. A–C: Parallel or straight extinction (0°). D–F: Inclined or obliqueextinction (20°). G–I: Symmetrical extinction (45°).

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Mediterranean marine sediment core database: Unlocking
paleoclimate signals for the last 20,000 years
Allyson Viganò

Università di Padova, Dipartimento di Geoscienze, & Dipartimento di Ingegneria Civile, Edile e Ambientale – ICEA, Padova, Italy;
allyson.vigano@unipd.it

Claudia Agnini

Università di Padova, Dipartimento di Geoscienze, Padova, Italy; claudia.agnini@unipd.it

https://doi.org/10.58998/jnr3296
The Mediterranean Sea is a key area for the study of the dynamics of past climates thanks to its unique geography andhydrology. Its relatively small size and rapid response to climate change make it an ideal laboratory for deciphering theimpact of marginal basins on global climate (Chiggiato et al., 2023). Within this context, climatic indicators (proxies)
serve as indispensable tools for characterizing intervals for which instrument records are not available. Furthermore,they can be used to construct future scenarios.
Here, we present a comprehensive database derived from more than 1500 marine sediment cores collected in the
Mediterranean Sea that span the last 20,000 years, or from the Last Glacial Maximum (LGM) to the present day. This
database provides general information about oceanographic cruises and detailed descriptions of the recovered sedimentcores. For each core, proxies of the primary environmental variables are provided from the literature.
The main aim of this effort was to identify the most studied variables and proxies used for the reconstruction of past
climatic conditions over the last 20 kyr, as well as to identify any knowledge gaps in terms of proxies and space and timecoverage. We have compiled climatic data from over 400 scientific articles and selected 36 cores from the Mediterranean Sea, including both extensively studied cores and those with potential significance for future research efforts. One
notable aspect of this work is to offer a comprehensive graphic basin-scale synthesis of the main environmental variables
available in the Mediterranean Sea over the last 20 kyr and to categorize the available proxies into abiotic (76%) andbiotic (24%) proxies. Among the biotic proxies, foraminifera are the most studied, followed by calcareous nannofossils.
Available paleoclimatic data on calcareous nannofossils have a fairly even distribution across the Mediterranean Sea
and are primarily derived from quantitative assemblage studies, reworked coccoliths, and changes in the abundance ofspecific taxa (e.g., Emiliania huxleyi and Florisphaera profunda).
References:
Chiggiato, J., Schroeder, K., Mourre, B., Miramontes, E., Lionello, P., Marcos, M., Pinardi, N., Mason, E., Álvarez, M. & Trincardi, F. 2023. Introduction. Oceanography of the Mediterranean Sea: An Introductory Guide. Elsevier: 1–11.

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Unlocking the mystery of Clausicoccus subdistichus acrossthe Eocene–Oligocene transition
Allyson Viganò

Università di Padova, Dipartimento di Geoscienze, & Dipartimento di Ingegneria Civile, Edile e Ambientale – ICEA, Padova, Italy; allyson.
vigano@unipd.it

Claudia Agnini

Università di Padova, Dipartimento di Geoscienze, Padova, Italy; claudia.agnini@unipd.it

https://doi.org/10.58998/jnr3297
During the Eocene–Oligocene transition (EOT), Earth's climate shifted from a warm, unglaciated state to a cold, glaciated state as large ice sheets developed on Antarctica. At the same time, a sudden increase in the calcareous nannofossil
Clausicoccus subdistichus is documented in many land sections and deep-sea drilling sites. In addition to the demonstrated value of biostratigraphic events associated with this taxon, questions and uncertainties remain regarding thesensitivity and significance of this taxon in relation to Antarctic glaciation.
Here, we present morphometric and abundance data of the C. subdistichus group (i.e., C. subdistichus and C. fenestratus) from the Indian (Ocean Drilling Program [ODP] Site 756), Pacific (International Ocean Discovery Program[IODP] Site U1509; ODP Site 1209), and Atlantic (Integrated Ocean Drilling Program Site U1411) Oceans. Our data
reveal a synchronous increase in abundance (acme event) and size of the C. subdistichus group at these sites across theEOT. We interpret this increase as a response to enhanced productivity conditions that were the result of an increase in
the northward water transport of nutrients from the Southern Ocean to low and middle latitudes caused by the ice buildup
on Antarctica. This hypothesis is further supported by independent proxies, such as opal and benthic foraminiferal accumulation rates, reported from the Southern Ocean and low–middle latitudes, respectively (Diester-Haass & Zahn,
1996: Coxall & Wilson, 2011).
The increase in size of the C. subdistichus group is associated with a positive global δ13C anomaly, which correlates
2with an oversaturation of [CO3 ] in seawater that previously was attributed to global shifts in carbonate production andburial (Merico et al., 2008). A partial contradiction arises from the non-standard, high abundance and large cell size
observed for C. subdistichus across the EOT, which contradicts the typical behavior observed in other nannoplankton
taxa (e.g., Reticulofenestra) under conditions of high productivity (i.e., high abundance, small size). This discrepancy
may be related to the peculiar carbonate geochemistry of the ocean at the onset of Antarctic glaciation.

References:
Coxall, H.K. & Wilson, P.A. 2011. Early Oligocene glaciation and productivity in the eastern equatorial Pacific: Insights into global carbon cycling.
Paleoceanography, 26: 1–18. https://doi.org/10.1029/2010PA002021
Diester-Haass, L. & Zahn, R. 1996. Eocene–Oligocene transition in the Southern Ocean: History of water mass circulation and biological productivity.
Geology, 24: 163–166. https://doi.org/10.1130/0091-7613(1996)024%3C0163:EOTITS%3E2.3.CO;2Merico, A., Tyrrell, T. & Wilson, P.A. 2008. Eocene/Oligocene ocean de-acidification linked to Antarctic glaciation by sea-level fall. Nature, 452:
979–982. https://doi.org/10.1038/nature06853

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Early and Middle Jurassic Tethyan calcareous nannofossil
zonation: Taxonomic updates and biostratigraphic improvements
Stefano Visentin

Eni SpA – Department SPES, Sedimentology, Petrography & Stratigraphy, 20097 San Donato Milanese, Italy; stefano.visentin@eni.com

Giulia Faucher

GEOMAR Helmholtz Centre for Ocean Research Kiel, 24148 Kiel, Germany; gfaucher@geomar.de

Elisabetta Erba

Università degli Studi di Milano, Dipartimento di Scienze della Terra “Ardito Desio,” 20133 Milano, Italy; elisabetta.erba@unimi.it

https://doi.org/10.58998/jnr3298
Biostratigraphic investigations of Tethyan sections, which span the Toarcian–lower Bajocian interval and have been
published in the last two decades, were collected and compared with standard schemes. This assessment found that
there were some discrepancies in the succession of events based on biozonations, which has resulted in our revision of
the age of some biohorizons. Moreover, some new/additional nannofossil events are proposed as subzonal markers. A
morphometric analysis of the genus Watznaueria, whose specific distribution is crucial for Jurassic biostratigraphy, wasalso conducted to identify diagnostic features that make possible unambiguous identification of the marker species W.
colacicchii, W. contracta, and W. britannica. Moreover, a new species, W. gaetanii, was established based on a different
bridge ultrastructure.
This work attests to the utility of establishing new biohorizons for Tethyan stratigraphic successions because they
offer the ability for a more precise age dating of Lower to Middle Jurassic key sections. This more detailed chronostratigraphic framework is extremely useful, both for the oil and gas industry and for academic research. Moreover, this study
provides new evidence of a comprehensive intrageneric evolutionary lineage that started in the Toarcian and accelerated
during the Aalenian under stable paleoceanographic conditions in an oligotrophic regime.

INA19131

Confocal laser imaging of calcareous nannofossils
Nikoleta Vitsou

Christian-Albrechts-University of Kiel, Institute of Geosciences, Kiel, Germany; stu242488@mail.uni-kiel.de

Claire M. Routledge, Denise K. Kulhanek

Christian-Albrechts-University of Kiel, Institute of Geosciences, Kiel, Germany; claire.routledge@ifg.uni-kiel.de; denise.kulhanek@ifg.uni-kiel.de

https://doi.org/10.58998/jnr3299
Calcareous nannofossils are typically studied using various transmitted light microscope techniques, including crosspolarized light and phase contrast, as well as scanning electron microscopy (SEM). Light microscopy takes advantageof the anisotropy of calcite, which allows coccoliths to produce birefringence under cross-polarized light. Sample preparation for the light microscope is simple and quick. Scanning electron microscopes provide much higher resolution,
allowing imaging of the detailed structure of calcareous nannofossils, but this method requires coating the sample with
an ultrathin layer of a non-reactive metal (such as gold or gold-palladium) prior to analysis. Additionally, SEM analysis
is done under vacuum, which requires extra time during analysis. Here, we show results from a new imaging technique,confocal laser scanning, using a Keyence VK-X3000 digital microscope. Sample preparation for this method is similar
to that for the light microscope, with the exception that no coverslip is placed over the sample, allowing the laser directaccess to the material. The microscope is equipped with a 100× objective to allow high-resolution imaging of specimens.
The digital microscope software allows users to take multiple images through a specimen to create a 3D image, which
can then be analyzed using a variety of measurements. The laser scanning technique creates high-resolution images thatshow detailed coccolith structure, analogous to SEM images. We compare images taken with the confocal laser scanningtechnique with those using standard light microscopy and SEM. We conclude that the confocal laser scanning technique
is a fast and easy-to-use microscopy technique for examining coccolith structure.

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Calcification response of Emiliania huxleyi to temperatureand pH variations under calcitic and aragonitic sea conditions
Han Wang

Sorbonne University, Laboratoire d’océanograpghie et du climat (lOCEAN), 75005 Paris, France; han.wang@locean.ipsl.fr

Diana Ruiz-Pino

Sorbonne University, Laboratoire d’océanograpghie et du climat (lOCEAN), 75005 Paris, France; diana.ruiz-pino@locean.ipsl.fr

Silvia Gardin

Sorbonne University, CR2P, 75005 Paris, France; silvia.gardin@sorbonne-universite.fr

Ian Probert

Station Biologique de Roscoff, 29682 Roscoff, France; probert@sb-roscoff.fr

Gerald Langer

Autonomous University of Barcelona, ICTA, 08193 Bellaterra, Spain; gerald.langer@cantab.net

Luc Beaufort

CEREGE, 13090 Aix-en-provence, France; beaufort@cerege.fr

https://doi.org/10.58998/jnr3300
Climate change and ocean chemical composition variation have occurred over extended geological periods. During
these times, coccolithophores, a crucial group of pelagic calcifiers, have historically either adapted to these fluctuations
or suffered biocalcification crises. Notably, the seawater magnesium/calcium, oscillating between aragonitic seas (>2)
and calcitic seas (<2), significantly impacts coccolithophore biocalcification. Additionally, variations in ocean temperature and pH, as climate change stressors, are critical factors influencing this process. Although the combined impacts ofocean acidification and warming have been shown to have an interactive effect on coccolithophores, the response of theclimate change stressors under different seawater Mg/Ca remains understudied. Here we performed a comprehensive
analysis of the coeffects of temperature and pH under aragonitic/calcitic seas (defined by different Mg/Ca) on the biocalcification of coccolithophores, providing insights into their mechanisms of response to changing marine environments
in both past and present oceans.
We cultured Emiliania huxleyi (RCC963) with artificial seawater under a range of Mg/Ca (0.2, 1, 5), temperatures(15°C, 21.5°C, 28°C), and pH (7.4, 7.8, 8.2) to evaluate the physiological traits and calcification sensitivity by measuring
the growth rate (μ), calcification rate, and coccolith morphology. Our findings indicate that in a calcitic sea, E. huxleyi
is more vulnerable in its growth rate to changes of temperature and pH as compared to an aragonitic sea. Coccolithmorphology also supports different responses to the Mg/Ca variations, with more malformed and incomplete coccoliths
observed under decreasing temperature and pH in an aragonitic sea. Additionally, in an aragonitic sea, increased temperature negatively impacts the calcification rate under low pH conditions, whereas in a calcitic sea with higher Mg/
Ca analogous to the Cretaceous Period, coccolithophore calcification was less affected by climate change stressors.
These findings suggest that acidification and warming impacts vary with oceanic Mg and Ca levels. Replication of theseexperiments across a broader range of Mg/Ca and different species will provide valuable insights into the impacts ofhistorical climate changes on ocean biocalcification crises and enhance understanding of coccolithophore evolutionary
responses to shifts in ocean chemistry over geological timescales.

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Late Paleocene eastern Tethys paleoenvironmental
reconstruction using calcareous nannofossils in the Patala
Formation, Salt Range, Pakistan
Xuejiao Wang

Polar Research Institute of China, Shanghai, 201209, China; xuejiaowang410@hotmail.com

https://doi.org/10.58998/jnr3301
The Paleocene/Eocene (P/E) boundary, which correlates with the thermal maximum event, is one of the most importanttransitions in the Cenozoic. In some studies, the P/E boundary is marked by an unconformity in the Kohat-Potwar Basin,
whereas others put it within the Patala Formation. In this study, calcareous nannofossil assemblages from the Patala
Formation in the Trans-Indus Range allowed identification of the P/E boundary and reconstruction of the paleoenvironmental thermal conditions. The Patala Formation is placed in Zone NP9 based on the first occurrence of Discoastermultiradiatus and the consistent occurrence of Calciosolenia aperta and Fasciculithus richardii. The co-occurrence ofPaleocene, Eocene, and Cretaceous species in the Patala Formation is due to unconformities both at the formation’s
upper and lower boundaries in the Trans-Indus Range. The P/E boundary corresponds to the unconformity between the
Patala Formation and the overlying Nammal Formation, which is likely the result of the India–Asia collision at 56–55
Ma. Malformed assemblages of the Discoaster araneus group and Rhomboaster spp., which characterize the Paleocene–
Eocene Thermal Maximum (PETM) event, were identified in the Patala Formation, whereas the pre-PETM phase could
be identified by decreasing diversity and abundance of the genus Fasciculithus. The neritic PETM event found in the
Tethys Sea is characterized by low salinity and increasing productivity due to terrestrial input. The Patala Formation also
contains an increase in low-salinity species and higher productivity. Moreover, the synchronous increased productivity
could be the result of higher temperatures due to the onset of the thermal maximum event. Abundant calcareous nannofossils indicate a stable sea level in the Trans-Indus Range, which might be deeper than inner neritic environments.

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Cretaceous–Paleogene calcareous nannofossils and theirbiostratigraphic and paleoceanographic implications insouthern Tibet
Yasu Wang

Hohai University, College of Oceanography, Nanjing 245700, China; wangyasu@hhu.edu.cn

Shijun Jiang

Hohai University, College of Oceanography, Nanjing 245700, China; ssj0047@my.fsu.edu

Hong Su

Jinan University, College of Life Science and Technology, Guangzhou 510632, China; suhong301@jnu.edu.cn

Denise Kulhanek

Christian-Albrechts-University of Kiel, Institute of Geosciences, 24118 Kiel, Germany; denise.kulhanek@ifg.uni-kiel.deDavide Persico

University of Parma, Department of Chemistry, Life Sciences and Environmental Sustainability, Parma, 43124, Italy; davide.persico@unipr.it

https://doi.org/10.58998/jnr3302
Tibet, known as the Earth's third pole, was once part of the eastern Tethys Ocean and now serves as a key region for paleoceanographic and paleoclimate research due to its arguably most complete, continuous Cretaceous through Paleogene
marine strata in China. Previous studies have shown that this region contains reasonably well-preserved and diverse
calcareous nannofossil assemblages, with over 100 nannofossil species identified from the Upper Cretaceous, morethan 60 from the Lower Cretaceous, and over 60 from the Paleogene. These findings not only demonstrate the diversity
and preservation of Tibetan nannofossils but also form the foundation for Cretaceous–Paleogene paleoceanographic
research. However, there are significant challenges, such as harsh geography, intense tectonic activity, diagenesis, andterrestrial dilution, which collectively hinder nannofossil studies. Consequently, there have been few calcareous nannofossil biostratigraphic studies in Tibet, highlighting the need for innovative approaches, international collaborations,and unwavering perseverance in research.
Recent studies in Tibet over the past decade have advanced the application of calcareous nannofossils in identifying
significant geological events and paleoceanographic changes. These studies were conducted primarily in southern Tibet,
which was formerly part of the India Plate, and they emphasize the importance of accurate biostratigraphic frameworks
for understanding the paleoceanographic evolution of the region. To date, nannofossils have been instrumental in dating
the Oceanic Anoxic Event (OAE) 1b, OAE 1d, and OAE2, the Cretaceous/Paleogene (K/Pg) boundary, and the India–
Eurasia plate collision. They also indicate that the final closure of the eastern Tethys Ocean in the early Eocene was due
to tectonic uplift, which may have caused Cretaceous fossils to be extensively redeposited into Paleogene sediments.
Paleoceanographic conditions can be inferred from nannofossil assemblages using species with specific ecological preferences to indicate variations in ocean surface temperature and nutrient conditions, which can be formulated as temperature and nutrient indices, respectively. These indices provide valuable insights into past oceanographic conditions andcontribute to our understanding of climate change over geologic timescales.
Acknowledgements:

This work was jointly funded by the National Key R&D Program of China (2022YFF0800800) and the National Natural
Science Foundation of China (No. 42372004, 42206047).

INA19135

Impact of the biological carbon pump on atmospheric pCO2
over the past 800,000 years
Yu Wang

Universities of Paris Sud and Paris-Saclay, GEOPS, CNRS, 91405 Orsay, France; yu.wang@universite-paris-saclay.fr

Stéphanie Duchamp-Alphonse, Sophie Sepulcre, Julius Nouet

Universities of Paris Sud and Paris-Saclay, GEOPS, CNRS, 91405 Orsay, France; stephanie.duchamp@universite-paris-saclay.fr;
sophie.sepulcre@universite-paris-saclay.fr; julius.nouet@universite-paris-saclay.fr

Margaux Brandon

NIOZ Royal Netherlands Institute for Sea Research, Landsdiep 4, Texel, The Netherlands; margaux.brandon@nioz.nl

Elisabeth Michel, Amaëlle Landais

LSCE/IPSL Laboratoire des Sciences du Climat et de l’Environnement, CEACNRS-UVSQ, 91198 Gif-sur-Yvette, France;
Elisabeth.Michel@lsce.ipsl.fr; amaelle.landais@lsce.ipsl.fr

Vikki Lowe, Johan Etourneau, Xavier Crosta

Université Bordeaux, CNRS, Bordeaux INP, EPOC, UMR 5805, F-33600 Pessac, France; EPHE/PSL Research University, Paris, France;
info@vikkilowe.com; johan.etourneau@u-bordeaux.fr; xavier.quidelleur@universite-paris-saclay.fr

Anna-Chiara Bartolini

Sorbonne Université, Muséum National d’Histoire Naturelle, Département Origines & Évolution, CR2P MNHN, CNRS, 75005, Paris, France;
annachiara.bartolini@mnhn.fr

https://doi.org/10.58998/jnr3303
Atmospheric CO2 concentration (pCO2) varied in a cyclic pattern over recent glacial–interglacial cycles, a phenomenon
that is mainly related to carbon uptake and release in the ocean. One important hypothesis invokes the role of marine
productivity, namely the biological carbon pump (BCP), where the production and downward export of phytoplanktonic
and planktonic organic and inorganic carbon act as a sink and a source of CO2 for the atmosphere, respectively. Evidence
points toward the BCP having an important role in modulating pCO2 over the last glacial cycle, but its evolution andimpacts on the climate system beyond that period remain elusive.
For this study, micropaleontological, geochemical, and scanning electron microscope analyses of sediment core
MD04-2718 (48°53.31'S, 65°57.42'E), which was retrieved in the Indian sector of the Subantarctic zone (SAZ), werecombined with data from published papers. With this information, we were able to reconstruct millennial changes in the
BCP strength over the last 800 kyr and integrate these changes within a coherent glacial–interglacial climate scenariothat includes variations in pCO2. In detail, we show that the carbonate (CaCO3%) and organic (TOC%, δ13Corg, C/N) fractions of the studied core reflect coccolith, planktonic foraminifera, and organic matter export productivity, respectively,
and that the TOC/CaCO3 may be used as a powerful tool to reflect changes in the BCP. An increased BCP during glacial
periods is related to increased phytoplanktonic organic carbon export production and is probably due to the fertilization
effect of enhanced iron-rich dust supply. A decreased BCP during interglacial periods reflects enhanced coccolith andplanktonic foraminifera export production, probably due to increased sea surface temperatures and the reinvigoration ofSouthern Ocean upwelling that brought nutrient-rich water to surface waters. Overall, our results show that a strengthened BCP during glacials might help sequester CO2 into the deep ocean at the expense of the atmosphere, whereas aweakened BCP during interglacials might enhance ocean CO2 leakage.

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Understanding the specialized cellular mechanisms that
support calcification in coccolithophores
Glen Wheeler

Marine Biological Association, Plymouth, UK; glw@mba.ac.uk

https://doi.org/10.58998/jnr3304
Coccolithophores are a group of calcifying phytoplankton that play a major role in the global carbon cycle by producing most of the biogenic calcification that occurs in modern oceans. Extant coccolithophores calcify to very different
degrees, and heavily calcified species contribute to most of the carbonate flux to the deep ocean. The degree of calcification also has an important impact on coccolithophore physiology. In lightly calcified species, calcification represents
only a minor fraction of total cellular carbon fluxes, whereas in heavily calcified species, calcification can occur at up to
twice the rate of photosynthesis. We have been investigating the physiological processes that enable coccolithophores toperform intracellular calcification at such remarkable rates by focusing on the mechanisms of calcium and carbon uptake
and subsequent regulation of intracellular pH. Direct measurements of the cellular microenvironment around coccolithophore cells have allowed us to determine how carbonate chemistry changes around the cell during calcification andhave provided insight into the interactions between photosynthesis and calcification. Furthermore, we have identified anovel family of calcium channels that are likely to play an important role in supporting the high rates of calcium uptake
required by coccolithophores. These calcium channels are found in all haptophytes, but have become greatly expandedin the calcifying lineages, which supports their potential role in coccolith formation. In combination, our results demonstrate major physiological differences between lightly calcified and heavily calcified coccolithophore species that likely
contribute to their distinct biogeographical distributions. Understanding how coccolithophore physiology is constrainedby these specialized mechanisms is important if we are to have a better understanding of their response to future environmental changes.

INA19137

A high-resolution depth profile of coccolithophores fromoligotrophic waters in the North Atlantic Gyre (part 2)
Amos WinterIndiana State University, Earth and Environmental Systems, Terre Haute IN, 47809, USA; Amos.Winter@indstate.edu

Josué G. Millán

Indiana State University, Earth and Environmental Systems, Terre Haute IN, 47809, USA; JMIllan1@sycamores.indstate.edu

Jeremy Young

University College London, Department of Earth Sciences, London, UK; jeremy.young@ucl.ac.uk

Hartmut Schulz

Tübingen University, Faculty of Sciences and Mathematics, Tubingen, Germany; hartmut.schulz@uni-tuebingen.deRichard Lotspeich

Indiana State University, Department of Economics, Terre Haute IN, 47809, USA; Richard.Lotspeich@indstate.edu

https://doi.org/10.58998/jnr3305
We report abundances and vertical distribution of coccolithophore species from samples retrieved on 28 January 2015
by the RV Meteor during cruise M113/2 at station #39 located at 31.46˚N, 44.44˚W in the North Atlantic Gyre. Thislocation is representative of oligotrophic regions of oceans with a deep chlorophyll a maximum at 120 m. Oligotrophic
regions account for 70% of the photosynthetic volume of the oceans. We seek to understand not only the biogeographic
distribution of coccolithophores but also their contribution in this region to the biogeochemical cycling of carbon. Our
results so far include:
1. Whenever possible, at least 300 specimens at 24 depths, from 5 m to 400 m, were evaluated with a scanningelectron microscope (SEM) to determine community composition. We counted and digitally imaged over 5000
coccolithophore specimens. Each was placed and catalogued in the interactive database Nannotax.
2. Living coccolithophores were detected in the water column down to 250 m and possibly to 300 m, as determinedby abundance patterns.
3. We estimate that >4.5 × 107 living coccolithophores were in the samples retrieved from the water column that westudied. The highest abundances, >4.2 × 104, occurred at 50 m during the winter/spring mixing season.
4. We identified 158 species from mostly phytoplankton groups but also some zooplankton. Of these species, 123
were identified as coccolithophores, including possibly a few undescribed species. Total species diversity isvery high compared to about 280 known oceanic coccolithophore species. About 30 species are represented by asingle sample, suggesting we might find more species by searching the filters further.
5. The assemblage is typical of the North Atlantic Gyre (excluding the Sargasso Sea community), which can becharacterized by depth zones (surface layer, mixed/deep chlorophyll maximum, and shadow community). Having clearly characterized assemblages allows comparison with other vertical transects.
6. The mixed layer is remarkably homogeneous during the winter/spring season, both in terms of composition andcoccolithophore morphology. There is no obvious change in morphology with depth, even for Emiliania huxleyi
or Umbellosphaera spp., contrary to findings in the western Sargasso Sea.
7. Low numbers of holococcolithophores and high levels of E. huxleyi possibly reflect a mildly oligotrophic environment due to mixing that occurred during sampling.
8. The Syracosphaeraceae are especially well represented, whereas the Papposphaeraceae are the major missing
group.
9. Despite making >5000 coccosphere images, we found no combination coccospheres.
10. Only about 10 specimens are assigned to undescribed taxa, thus >99.5% can be reliably identified.
11. This large set of images was collected without any selection, which means they could be used to acquire goodquality data on variations in coccolith size, coccosphere size, and liths per sphere.

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Paleocene to Eocene calcareous nannofossil zonation in thewestern Tarim Basin, Central Asia
Dangpeng Xi

China University of Geosciences, State Key Laboratory of Biogeology and Environmental Geology, Beijing, 100083, China; xdp1121@163.com

Xuejiao Wang, Dan Liu, Xiaoqiao Wan

China University of Geosciences, State Key Laboratory of Biogeology and Environmental Geology, Beijing, 100083, China;
xuejiaowang410@hotmail.com, ld2276088@163.com, wanxq@cugb.edu.cn

https://doi.org/10.58998/jnr3306
The western Tarim Basin, which is located between the Tianshan Mountains and the Kunlun Mountains of Central Asia,
was covered by the shallow, epicontinental, northeastern part of the Tethys Sea from the Late Cretaceous to Eocene. According to previous studies, marine sediments containing calcareous nannofossils are found in the Paleogene Qimugen,
Kalataer, Wulagen, and Bashibulake Formations. In this study, calcareous nannofossil assemblages from four sections(Bashibulake, Kuzigongsu, Simuhana, and Aertashi) were correlated to discuss the biostratigraphy in the western Tarim
Basin. The Qimugen Formation is placed in nannofossil Zones NP7–10 (Thanetian to Ypresian) in the Tianshan Mountain area, in which the first occurrences of Heliolithus riedelii, Discoaster multiradiatus, and Rhomboaster/Discoaster(RD) assemblages (namely, Discoaster araneus group and Rhomboaster spp.) have been recorded. The Paleocene–Eocene Thermal Maximum (PETM) is well defined by the RD assemblages in the western Tarim Basin. The top of the
Qimugen Formation is placed in Zones NP10–11 (Ypresian) as identified by the last common occurrence of Discoastermultiradiatus in the Tianshan Mountains region. In the Kunlun Mountains area, the Qimugen Formation is placed in
Subzones NP9a and NP9b based on the first occurrence of D. multiradiatus and the D. araneus group in the Aretashi
section. The Kalataer and Wulagen Formations are placed in Zones CNE12–13 (Lutetian) based on the occurrences of
Nannotetrina spp., Discoaster bifax, Reticulofenestra umbilicus, Cribrocentrum reticulatum, and Chiasmolithus solitus
in the Tianshan Mountains area. In the Kunlun Mountains area, by analyzing the extension of the co-occurrence ofR. umbilicus and C. solitus in the Aertashi section, the calcareous nannofossil layer in the Wulagen Formation is placedin Zone NP16 (late Lutetian to Bartonian). The middle part of the Bashibulake Formation is placed in Zone CNE17(Bartonian/Priabonian) based on the common occurrence of Cribrocentrum erbae.

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Developing tools to compile and visualize nannofossil occurrence data
Jeremy R. Young

University College London, Department of Earth Sciences, London, WC1E 6BT, UK; jeremy.young@ucl.ac.uk

Yi Zhang

Chine University of Geoesciences, Beijing, China; zhangyizy0532@163.com

Paul R. Bown

University College London, Department of Earth Sciences, London WC1E 6BT, UK; p.bown@ucl.ac.uk

https://doi.org/10.58998/jnr3307
The Neptune database is an invaluable compilation of planktonic microfossil occurrence data. Adding data from Neptune into Nannotax has provided effective visual summaries of the abundance and stratigraphic distribution of taxa.
However, the data in Neptune are mostly >20 years old, are exclusively from ocean drilling cores, and coverage of the
Mesozoic is rather sparse. Recently, we have been working on an extended Cretaceous nannofossil occurrence database.
This is intended both for research, to allow investigation of the autecology of nannofossils and their response to environmental change, and for documentation of their stratigraphic occurrence on Nannotax.
We have developed the database so that all data uploading, editing, and displaying are done via webpages as part of
the Nannotax system. The workflow is based on the upload of distribution tables (samples versus species) from a single
drill site or outcrop. First, metadata (location, analyst, source publication, etc.) for the table are entered via a form, andthen the table of data is uploaded as a tab-delimited file or spreadsheet. Next, a data-cleansing step ensures sample data
are consistently labeled and that the recorded taxa are correctly linked to entries in Nannotax. The data upload scriptthen populates the sample and occurrence tables. An optional step allows calculation of sample depths and entry of zonal
assignments. The uploaded data are then displayed, and age-diagnostic data are summarized in an age-depth plot thatallows a line of correlation to be drawn and ages assigned to the samples. Finally, paleolatitudes and paleolongitudes areadded using g-plates (this step requires use of an external script but can be done in large batches).
Data visualization primarily uses systems previously developed for use with the Neptune database, and this allows
plotting of range charts, distribution maps, and plots of occurrence frequency against time and paleolatitude. An extra
system has been developed to allow examination of all occurrence data from a single time-latitude defined interval.
Access to this database is currently restricted prior to publication, but it should be available by the end of 2024. An agedepth plotting tool is already directly accessible from Nannotax (tools menu), and the database development tools will
be available for future projects.

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Reconstructing Cretaceous climate: Insights from a new
calcareous nannofossil occurrence database
Yi Zhang

China University of Geosciences, Institute of Earth Sciences, Beijing 100083, China; zhangyizy0532@163.com

Jeremy R. Young, Paul R. Bown

University College London, Department of Earth Sciences, WC1E 6BT, London, UK; jeremy.young@ucl.ac.uk; p.bown@ucl.ac.uk

Xi Chen, Chengshan Wang

China University of Geosciences, Institute of Earth Sciences, Beijing 100083, China; xichen@cugb.edu.cn; wang.chengshan@ddeworld.org

https://doi.org/10.58998/jnr3308
The Cretaceous Period is recognized as a prototypical greenhouse climate interval, which is regarded as a potential
analog for predictions of future climate change. Historically, geochemical and paleontological proxies, such as δ18Oof carbonates, TEX86 paleothermometry, fossil assemblage abundances, and biogeography were used to reconstructpaleotemperature evolution during the Cretaceous. However, a comprehensive and integrated database of microfossil
occurrences, which is essential for thorough Cretaceous paleoclimate reconstructions, remains elusive.
Calcareous nannofossils were the dominant group of phytoplankton living in the photic zone of the Cretaceous
oceans, and their sensitivity to environmental factors makes them robust biotic proxies for sea surface temperaturereconstructions. While the Neptune database has provided substantial insights into the occurrence and distribution of
calcareous nannofossils, it predominantly features data that are over two decades old, with sparse coverage of the Cretaceous (~2600 samples) and a massive bias toward the Recent. To address these limitations and enhance the reliabilityof scientific research, we have compiled Cretaceous occurrence data from 111 sections that include onshore outcrops
and deep-sea drilling sites, which have new age-depth models with revised and robust age information. Around 8000
samples and 200,000 nannofossil occurrences from the Berriasian to Maastrichtian were added to the existing Neptune
database, tripling the data available. This initiative aims not only to investigate the paleoecological dynamics and environmental responses of nannofossils but also to ensure meticulous documentation of their stratigraphic occurrences,which will be detailed in a forthcoming version of Nannotax. Although access to this enriched dataset is currently restricted pending publication, it is anticipated it will be made publicly available by the end of 2024.
Utilizing this novel database, our research quantitatively evaluates the latitudinal distribution of common and paleoenvironmentally diagnostic nannofossil taxa at a high resolution through the Cretaceous. Our objectives include (1)assessing the paleotemperature preferences of Cretaceous calcareous nannoplankton to establish refined temperature
indices and (2) constructing a detailed evolutionary trajectory of Cretaceous sea surface temperatures, thereby contributing a novel perspective to the discussion of Cretaceous paleoclimate evolution.

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Journal of
Nannoplankton Research
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contents

1 Preface
6 Programme
11 Poster titles
14 Abstracts