IODP Proposal Cover Sheet

937 - Full

Deepening Hole U1309D

Received for: 2019-10-01

Title

2

Accessing the Building Blocks of Life: Deepening Hole U1309D, Atlantis Massif, Mid-Atlantic Ridge

Proponents

Andrew McCaig, Donna Blackman, Beth Orcutt, Benedicte Menez, Marvin Lilley, Geoffery Wheat, Johan
Lissenberg, Benoit Ildefonse, Frieder Klein, Susan Lang, William Seyfried, Muriel Andreani, Barbara John,
Marguerite Godard, Antony Morris, Esther Schwarzenbach, Christopher MacLeod, Ivan Savov, Natsue Abe,
Yasukiko Ohara

Keywords

serpentinization, hydrogen, methane, gabbro, fluid

Proponent
Affiliation
Country

Area

Mid-Atlantic Ridge

Proponent Information
Andrew McCaig
University of Leeds
United Kingdom✓⃞ Permission is granted to post the coversheet/site table on www.iodp.org

Abstract
The Atlantis Massif Oceanic Core Complex (OCC) is one of the best studied locations in the ocean crust, the site of four
IODP expeditions so far (304, 305, 340T and 357). It is the site of the Lost City Hydrothermal Field (LCHF), venting alkaline
fluids rich in hydrogen and methane at 40-90 centigrade. IODP Hole U1309D, located 5km north of the LCHF, is the deepest(1415m) hole so far drilled in young (<2 Ma) ocean crust, sampling a primitive series of gabbroic rocks interpreted in part tobe metasomatised peridotite. Gabbroic lithologies in Hole U1309D contrast with serpentinized peridotites sampled near the
LCHF by seafloor coring in Exp. 357 and sampling on the south wall of the Massif. The hydrologic regime is also very
different at the two locations, with deep permeability required beneath the LCHF, and a low permeability conductive regime
evidenced by a linear thermal gradient deeper than 750 mbsf in Hole U1309D.
The principle aim of this proposal is to sample fluids and rocks in a stable regime with temperatures higher than eversampled before by IODP. We hope to access temperatures above 200 centigrade, where active serpentinization is occurringin olivine-rich rocks, and where the building blocks for life (H2, CH4, and more complex organic compounds) may becreated abiotically.
In addition we will drill a short Hole close to the Lost City Hydrothermal Field in order to gain a complete section through a
detachment fault zone and address biosphere, structural and alteration objectives not completed in IODP Expedition 357
due to failure to penetrate to depths envisaged.
We will sample fluids in the existing Hole 1309D using newly developed temperature-sensitive sampling tools and leave aclean legacy hole reaching 2100 mbsf and temperatures of 220 C for future logging and fluid sampling once thermal
equilibrium has returned. H2, CH4, other organic molecules and cations will be sampled in fluid inclusions to compare with
ambient fluids. We hypothesise that concentration gradients in volatile species may exist in the Massif.
We will also study the magmatic evolution of oceanic core complexes including melt-rock reaction processes critical to theassembly and geochemistry of oceanic gabbro bodies and the relationship between plutonic rocks and MORB
Drilling to temperature regimes not previously accessed by IODP will allow the limitations of current technology to beevaluated in preparation for future deep drilling

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937 - Full

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Scientific Objectives
Our proposed drilling strategy will address a number of objectives in the Earth in Motion, Earth Connection and Biosphere Frontiers themesof the IODP Science Plan.
Objective 1: The life cycle of an oceanic core complex: Links between igneous, metamorphic, structural and fluid flow processes, andtesting of geophysical and hydrothermal models. This objective addresses Science Plan Challenge 9: "How are seafloor spreading andmantle melting linked to ocean crustal architecture?" Challenge 10: What are the mechanisms, magnitude and history of chemical
exchanges between the ocean crust and seawater" and Challenge 14: How do fluids link subseafloor tectonic, thermal, and biogeochemical
processes?
Objective 2: Accessing the chemical kitchen preceding the appearance of life on Earth: formation of organic molecules of prebiotic interest
at high and low temperatures in the Atlantis Massif. This objective addresses Science Plan challenge 10 "What are the mechanisms,
magnitude, and history of chemical exchanges between
the oceanic crust and seawater?", Challenge 13 “What properties and processes govern the flow and storage of carbon in the subseafloor”;
and Challenge 14 “How do fluids link subseafloor tectonic, thermal, and biogeochemical processes?” It will also be of great interest to the
Astrobiology Community studying hydrothermal processes on Icy Worlds and Mars
Objective 3: Deep biosphere and limits for life in the Atlantis Massif: controls of lithological substrate, porosity and permeability,
temperature, fluid chemistry and reactive gradients on microbiology. This objective concerns Science Plan Challenge 5 "What are the origin,composition, and global significance of deep
subseafloor communities?" and Challenge 6 "What are the limits of life in the subseafloor realm?"

Non-standard measurements technology needed to achieve the proposed scientific objectives
Sampling of fluids using downhole logging tools at selected intervals, in particular using shape metal alloy sampling systems currently underdevelopment
Preserving selected samples away from atmospheric alteration and potentially at near-ambient temperature above the temperature limits oflife

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937 - Full2

Proposed Sites (Total proposed sites: 3; pri: 2; alt: 1; N/S: 0)

Site Name

Position(Lat, Lon)

Water
Depth
(m)

Penetration (m)Brief Site-specific Objectives
Sed

AMDH-01A(Primary)

30.1687-42.1186

AMDH-02A(Primary)

30.1317-42.1202825

3

AMDH-03A(Alternate)30.1389-42.1455

1275

5

1656

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0

Bsm

Total

660

(i) Sample fluids and measure temperature in existing Hole 1309D down
to 1414 mbsf (expected temperature 225 centigrade). (ii) Deepen
existing Hole U1309D by ~650 m and collect samples for petrology andgeochemistry of abiotic organic compounds and H2; (iii) log Hole withflasked tools. (iv) Drill new 80m Hole 20-30 m north of Hole U1309D, formicrobiology sampling of porous rocks, fault zones, and correlation with
Holes U1309B and D. This Hole is designated "U1309-J" in the text andsite form. Note that Hole 1309C with protruding casing needs to be
avoided.

200

203200mHole with re-entry. Complete section through detachment fault zone
in serpentinized peridotite. Sample for deformation, alteration, igneous
petrology, microbiology and organic/inorganic geochemistry. Log fortemperature and other properties. Legacy Hole for sampling fluids andgases, establishing temperature profile, potential instrumentation

200

205

Drill through detachment fault shear zone; igneous petrology, alteration,
deformation fabrics, microbiology, organic geochemistry. potential for
post-detachment volcanic rocks. Temperature profile, fluid sampling,
potential to provide re-entry system for legacy

660

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Contact Information
Contact Person: Andrew McCaig
Department: School of Earth and Environment
Organization: University of Leeds
Address: Woodhouse Lane
Leeds West Yorkshire LS2 9JT United Kingdom
E-mail/Phone: a.m.mccaig@leeds.ac.uk;

Phone: +44 113 3435219

Proponent List
First Name

Last Name

Affiliation

Country

Role

Expertise

Andrew

McCaigUniversity of Leeds

United Kingdom

Principal
Lead

Donna

Blackman

UC Santa Cruz

United States

Data Leadgeophysics, heatflow

BethOrcuttBigelow Laboratory for Ocean Sciences

United States

Other Lead

Microbiology;
biogeochemistry;

Benedicte

Menez

IPGP Paris

FranceOther Leadgeomicrobiology;
geochemistry

MarvinLilleyUniversity of Washington

United States

Other Leadfluid geochemistry;hydrocarbons

Geoffery

Wheat

University of Alaska, Fairbanks

United States

Other Leadgeochemistry;
downhole sampling;hydrogeology

Johan

Lissenberg

Cardiff University

United Kingdom

Other Lead

igneous petrology

BenoitIldefonse

University of Montpellier

FranceOther Lead

igneous petrology;
tectonics; physicalproperties

Frieder

Klein

Woods Hole Oceanographic Institute

United States

Other Leadfluid geochemistry;
fluid-rock interaction

Susan

Lang

University of South Carolina

United States

Other Leadbiogeochemistry;geochemistry

WilliamSeyfried

University of Minnesota

United States

Other
Proponent

fluid geochemistry;
fluid-rock interaction

MurielAndreani

University of Lyon

FranceOther
Proponent

metamorphic petrology;
geochemistry

BarbaraJohn

University of Wyoming

United States

Other
Proponent

tectonics; petrology;
geochronology

Marguerite

GodardUniversity of Montpellier

FranceOther
Proponent

petrology;
geochemistry

AntonyMorris

University of Plymouth

United Kingdom

Other
Proponent

Palaeomagnetism; rockmagnetism; tectonics

Esther

Schwarzenbach

Free University Berlin

Germany

Other
Proponent

metamorphic petrology;
geochemistry

Christopher

MacLeod

Cardiff University

United Kingdom

Other
Proponent

tectonics, petrology

Ivan

Savov

University of Leeds

United Kingdom

Other
Proponent

geochemistry,
volcanology, petrology

NatsueAbe

Jamstec

Japan

Other
Proponent

Igneous petrology

Yasukiko

Ohara

Hydrographic and Oceanographic
Department of Japan

Japan

Other
Proponent

Marine geology andtectonics

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Alteration, tectonics,
structural geology

1. Introduction
1.1: Setting of Proposal
Atlantis Massif (30 °N, Mid-Atlantic Ridge) has been investigated by four IODP expeditions(304, 305, 340T and 357) and numerous other cruises (Blackman et al., 1998; Blackman and
Collins, 2010; Blackman et al., 2011; Blackman et al., 2013; Canales et al., 2004; Canales etal., 2008; Cann et al., 1997; Karson et al., 2006; Kelley et al., 2001; Kelley et al., 2005). It was
the first corrugated massif identified as an oceanic core complex (OCC), and hosts the Lost
City Hydrothermal Field (LCHF), which has vented alkaline fluids rich in H2 and CH4 attemperatures of 40-90°C for >100,000 years (Kelley et al., 2005; Ludwig et al., 2011;
Proskurowski et al., 2008). IODP Hole U1309D penetrated largely gabbroic rocks to 1415 mbsf
(Figs. 1-4) and contrasts with the southern wall of the Massif near LCHF, which consists
dominantly of serpentinized peridotite with ~20% gabbroic rocks (Fig. 2). A detachment fault
zone ~100 m thick forms the surface of the Massif (Karson et al., 2006; Schroeder and John,
2004) and the uppermost few meters of this was extensively sampled in IODP Expedition 357(Fig. 1, 4, 5) (Früh-Green et al., 2018). The fault zone comprises talc-tremolite-chlorite schists
overprinting serpentinite, with fault breccias and cataclasites locally overprinting higher
temperature fault rocks including amphibolites, gabbros, and syntectonic diabase dykes
intruded in the fault zone (Blackman et al., 2011; McCaig et al., 2010; McCaig and Harris,2012). The Massif was exhumed on this convex-up detachment fault bringing gabbro andperidotite onto the seafloor, with 45° rotation around a subhorizontal ridge-parallel axis below
the Curie temperature (Morris et al., 2009). U1309D core can be interpreted as an inclined
section plunging ≤ 45° through a previously active, moderate to steeply dipping detachment
fault zone and its footwall (Fig. 2, 6). One aim of Expedition 357 was to collect 80 m longnear-complete sections through the detachment fault zone close to the south wall, but the
maximum penetration of 16.4 m meant that only the uppermost part was sampled.
This proposal aims to:1.

Deepen Hole U1309D into the depth/temperature range where active serpentinization
reactions in olivine-bearing rocks likely to be occurring (Allen and Seyfried, 2004;
Seyfried and Dibble, 1980), together with abiotic synthesis of CH4, and other organic
compounds at temperatures where microbial synthesis is not possible. Fluid sampling will
be undertaken in the existing 1415 m deep Hole. If the target of 2060m is reached, Hole
U1309D will be the deepest Hole in young (<1.5 Ma) lithosphere with bottom
temperatures estimated at 220 °C.

2. Drill a new 200m deep Hole (AMDH-2A) within the footprint of Expedition 357, with added
focus on collecting microbiology samples in porous, permeable horizons. In conjunction
with Exp. 357 cores, this Hole will complete a section through the 100 m thick fault zone,
and amplify studies of microbiology, geobiology, organic and inorganic geochemistry ofpore fluids and cored rocks, petrology and structural geology.
3. Drill a new 80 m Hole at Site U1309 (“U1309-J”) to collect microbiology samples in fault
breccias and rocks containing reaction porosity to enable direct comparison of results fromthis mafic site with those obtained at ultramafic AMDH-2A.
To allow future deeper drilling, logging, fluid sampling and potentially borehole observatories,
we plan to install a re-entry system in Hole AMDH-2A and leave Hole U1309D open. Legacy
is a very important aspect of this proposal since some objectives require fluid sampling andtemperature measurements that are only viable several years after drilling.
This proposal addresses multiple challenges within the IODP Science Plan themes
Biosphere Frontiers, Earth Connections and Earth in Motion:
 Challenge 5: What are the origin, composition and global significance of deep subseafloor
communities?
 Challenge 6: What are the limits of life in the subseafloor realm?
 Challenge 9: How are seafloor spreading and mantle melting linked to ocean crustal
architecture?
 Challenge 10: What are the mechanisms, magnitude and history of chemical exchanges
between the ocean crust and seawater?
 Challenge 13: What properties and processes govern the flow and storage of carbon in theseafloor?
 Challenge 14: How do fluids link subseafloor tectonic, thermal, and biogeochemical
processes?

1.2: Response to SEP
SEP reviewed 937-Full in January 2019, supporting the scientific objectives of the proposal
while making a number of valuable comments and suggestions. Below we address theircomments:

1. Fluid sampling: SEP strongly recommended delaying resubmission until the new MultiTemperature Fluid Sampler (MTFS) tool had been tested on Exp. 385T. Although the
MTFS tool was fully ready for deployment, operational problems prevented testing.Our
revised plan uses both the proven Kuster tool and the MTFS. Fluid sampling is a key partof our U1309D legacy strategy, and therefore success of samplers on this expedition,
while desirable, is not essential to meet our long-term objectives.
2. Clarifying objectives and hypotheses: We have restructured the text to make objectives,deliverables and hypotheses clear throughout. Microbiology objectives show the resultsthat can be obtained by new deeper sampling compared to Expedition 357. We emphasize
a strategy to collect higher porosity intervals which are likely to yield higher cell counts.
3. Distinguishing formation water from intruded seawater: We will disturb Hole
U1309D fluid as little as possible during sampling prior to drilling. However the fluid willin any case be seawater partially reacted with rock and/or with some admixture offormation water. Deviations from seawater will be modelled using geochemical software
to predict endmember fluid compositions in equilibrium with rocks.
4. Effects of cooling on proposed geochemical targets: Cooling effects are well known inexperiments (for example significant pH changes) and can be corrected for to reconstructin situ composition in borehole fluids.
5. Operations plan: This has been expanded and modified to show which objectives can be
met in various circumstances.
6. Site survey: Site 4A has been removed: we accept it was an inadequate alternate for our
primary objectives. Zoomed-in velocity images were added on site forms.

2. Objectives
2.1: Objective 1: Life cycle of an oceanic core complex - Links between igneous,
metamorphic, structural and fluid flow processes
2.1.1: Scientific justification
2.1.1.1: Internal structure, cooling history and hydrogeology of the Massif
Hole U1309D revealed that the Atlantis Massif (AM) central dome is cored by gabbroic
rocks to a minimum depth of 1415 mbsf (Fig. 1). Recent Full Waveform Inversion (FWI) of
previous geophysical data (Harding et al., 2016) reveals (Fig. 3) much more detail thanprevious tomography (Canales et al., 2008) and suggests that the gabbro body with P-wave
velocities of 6-7 km/s extends southwards towards the LCHF with an irregular contact
against lower velocity rocks interpreted as serpentinized peridotites. However since velocitiesof 4-5 km/s characterise the altered gabbros in the upper part of Hole U1309D, and partiallyaltered peridotite could have velocities of 6-7 km/s, interpretations still need groundtruthing.
The heterogeneous structure beneath the LCHF may be the best indication of variably
serpentinised peridotites containing sill-like altered gabbro bodies.
The FWI velocity model only extends to the current base of Hole U1309D, but OBS
refraction tomography (Fig. 3D) suggests that the high velocities will continue to the 2060
mbsf depth of our proposed extension in AMDH-1A. However this velocity could include
significant intervals of partially altered ultramafic rocks similar to olivine-rich troctolites
between 1100 and 1200 mbsf in U1309D (Fig. 1). At some point the gabbroic body must
transition into mantle rocks, as discussed below.
Expedition 340T (Blackman et al., 2014) found that the temperature profile in U1309D was
conductive below 750 mbsf, with a gentle curvature suggesting slow downflow of fluid abovethat depth (Fig. 1). Minor excursions in downhole temperature at 750 and 1100 mbsf suggests
fluid influx into permeable fault zones. To vent at up to 90°C the LCHF must mine fluid toseveral km depth, based on inferences of circulation temperatures from fluid chemistry (Allenand Seyfried, 2004, 2005; Foustoukos et al., 2008a), and hydrothermal modelling (Lowell,2017; Titarenko and McCaig, 2015). At high levels the LCHF is localized by faulting (Dennyet al., 2016); whether more diffuse or multichannel flow occurs at depth, or if there isshallow recharge and mixing, is very important for the chemical and hence microbiologicalevolution of the system and therefore underpins all of our main objectives. A lateralpermeability change could stabilise and sustain the LCHF over long periods of time(Titarenko and McCaig, 2015). New measurements of the thermal structure and fluid flow at
depth close to Lost City will provide important constraints on the hydrogeology of AM.
Initial cooling of the Massif was rapid, based on palaeomagnetic (Morris et al., 2009) andgeochronological (Grimes et al., 2008; Schoolmeesters et al., 2012) data. This may have been
linked to circulation of black smoker fluids within the detachment fault zone (McCaig et al.,2010; McCaig and Harris, 2012), in an early phase of circulation compared to the current
Lost City phase.

2.1.1.2: Igneous processes. Rocks recovered in Hole U1309D include a sequence of primitive
gabbro and olivine gabbro (Fig.s 1, 4), with intervals of troctolite and olivine-rich troctolite.
Back-correcting for rotation, the diabase intrusions within the detachment zone could represent
a lateral dyke-gabbro transition (McCaig and Harris, 2012). Olivine-rich troctolites areinterpreted as mantle rocks modified by melt-rock reaction (Drouin et al., 2009; Ferrando etal., 2018; Lissenberg and MacLeod, 2016); less modified mantle rocks are confined to very
short intervals (< 1 m) at shallow depths. The gabbro contains many internal contacts (Suhr etal., 2008) and local igneous layering. Plutonic rocks recovered from U1309D are amongst themost primitive ever recovered (Fig. 4). Unlike other plutonic sections drilled (Pacific Ocean:
ODP Holes 147 and 1256D; Indian Ocean: ODP Holes 735B and 1105A, IODP Hole U1473A),
many of the AM plutonic rocks are in equilibrium with mid-ocean ridge basalt (MORB), withsome primitive enough to have formed directly from primary mantle melts. Hence, AM offersa unique opportunity to study the compositions of melts delivered to the crust from their mantle
source, and how they evolve to MORB. This is paramount; crustal evolution of melt is now
recognised to be significantly more complicated than previously realised, involving not only
fractional crystallisation, but in-situ crystallisation and reactive porous flow (Lissenberg and
MacLeod, 2016). Hence, interpreting MORB compositions, and implications for the upper
mantle, is highly non-unique, unless melt evolution processes in the lower crust are quantified.
Intervals of gabbro within south wall serpentinites (Fig. 5) have an uncertain relationship to
the main gabbro further north. They may be intrusions of different age or level of exhumation,or may be satellites of the larger body. Establishing the genetic relationship between thesebodies is important.

2.1.1.3 Integrated studies of deformation, fluid-rock interaction, magmatism anddeformation in a detachment fault zone.
The U1309D core was remarkable for the paucity of high temperature crystal-plastic fabrics,
compared to the only other deep OCC holes at Atlantis Bank (Ildefonse et al., 2007).
However, significant breccia intervals intruded by syntectonic diabase (Fig. 6) formed over arange of temperatures up to near magmatic in the top 100m of Site U1309 (Blackman et al.,2011; McCaig and Harris, 2012). Alteration is pervasive in the upper part of Hole U1309D,
and isotopic data shows the detachment fault zone to be highly altered by seawater-derived
fluids at temperatures similar to black smoker fluids (McCaig et al., 2010). Greater intensities
of crystal-plastic deformation were found in gabbroic lenses in peridotite on the south wallof the Massif (Schroeder and John, 2004), and in the shallow cores of Exp. 357 (Früh-Greenet al., 2018).
Intense alteration in the shallow Expedition 357 cores (Früh-Green et al., 2018; Rouméjon etal., 2018) is generally consistent with previous work on the south wall (Boschi et al., 2006).
Early serpentine replacing olivine is locally overprinted by talc-tremolite-chlorite assemblages,
often associated with mafic intrusions and/or shearing. Carbonate veining is surprisingly rareconsidering the proximity of several holes to Lost City (Fig. 1). Extensive water-rockinteraction at variable temperatures is further reflected in heterogeneous sulphur isotope
compositions. These document a complex evolution of the hydrothermal system with episodesof low temperature serpentinization and incorporation of seawater sulphate facilitating
microbial activity and episodes of high temperature water-rock interaction controlled by the
intrusion of microgabbroic veins, which is accompanied by considerable mass transfer(Liebmann et al., 2018).
Reaction permeability is common in the upper part of Holes U1309B and D, and has beenfound in chloritized gabbros in core from Exp. 357 (Fig. 7). Rapid dissolution of primaryminerals can occur if far-from-equilibrium hot fluid is in excess, as is likely in the upflow zoneof a black-smoker system (Cann et al., 2015). We will target sampling of reaction permeability
and other permeable zones for geochemical and microbiology investigations (see also
objectives 2 and 3), and seek to quantify the extent of reaction permeability in both the gabbroic
and serpentinite fault zones.

2.1.1.4: Alteration, fluid-rock geochemistry and cooling history of AM
Alteration in U1309D records progressive fluid influx during cooling from magmatic toambient temperatures. It is pervasive above 350 m, with olivine-plagioclase corona reactions
reflecting temperatures above 500°C (Nozaka and Fryer, 2011). Deeper, the corona reaction
is restricted to the vicinity of fault zones and lithologic contacts, but partial serpentinizationof olivine is common in many intervals, often accompanied by prehnite and hydrogarnet
replacing plagioclase (Frost et al., 2008). Serpentinization reactions are complex, including
early brucite-antigorite veins followed by lizardite-magnetite (Beard et al., 2009). Lower
temperature serpentinite is often accompanied by saponite (Nozaka et al., 2008), and this has
recently been shown to contain (Fig. 8; see also objective 2) abiogenic amino acids (Ménez
et al., 2018). Sr and O isotope alteration by seawater-derived fluids is common in the upper
part of the hole, but decreases below 350 mbsf, and is mainly present in serpentine-richintervals where the primary Sr content is low, and the seawater signal may be carried bycarbonates (McCaig et al., 2010).
Field and experimental studies demonstrate that dissolved silica, boron, lithium, oxygen andstrontium isotopes, together with redox constraints imposed by dissolved H2 and coexisting
sulfur species, provide important clues to the role of heat and mass transfer reactions on thechemical evolution of hydrothermal fluids (Allen and Seyfried, 2003; Foustoukos et al., 2008b).
These data help constrain temperature, fluid/rock mass ratio, and potential sources of silica that
may involve alteration of gabbro and/or peridotite (Bach et al., 2004; Bach and Humphris, 1999;
Seyfried et al., 2015; Tutolo et al., 2018). Borehole fluid observations over a range oftemperatures, will permit assessment of cooling-induced pH changes and B isotope
fractionation processes, with insight on the effect of temperature on stable and metastable fluidmineral equilibria. Modeling the effect of temperature and cooling on mineral solubility data
and redox processes will be part of our study. Measurement of dissolved Ca, Mg and silica inborehole fluids will constrain phase equilibria and reaction kinetics involving serpentine
minerals, possibly coexisting with tremolite and talc (Seyfried et al., 2004). Olivine
metastability will be assessed from constraints imposed by dissolved silica and cation budget,
together with mineral based observations. Our deepened Hole will be the first in ocean drillingto access temperatures above 200°C in a stable environment.

Serpentinization reactions take up boron and lithium from seawater, with many samples
from the Atlantic enriched in boron with high values of δ11B (Boschi et al., 2008; Harvey et al.,2014; Vils et al., 2009). These data have led to an assumption that all serpentine in subducting
slabs will be enriched in boron, and can contribute to high [B] and δ11B, and systematic crossarc changes in subduction zone volcanics (Konrad-Schmolke and Halama, 2014). However,data from Hess Deep suggest boron is easily removed from percolating seawater in crustal
sections (McCaig et al., 2018), never reaching the underlying mantle. We will test the
hypothesis that the boron and lithium seawater signatures die out with depth in the Hole byboth whole rock and in situ analysis.

2.1.2: Expected outcomes:
We will study the evolution of the Atlantis Massif by deepening Hole U1309D to ~2060 mbsf,
accessing ambient temperatures from 147 to ~220 °C, and by drilling a new 200m hole inserpentinite containing gabbro and mafic dykes close to the LCHF.
Objective 1 deliverables:
1A: Borehole fluids collected at temperatures up to 145 °C, particularly above and below
zones of suspected fluid ingress into Hole U1309D, with aim for future sampling up to220 °C.
1B: Rock samples, forming part of the longest continuous section through young gabbroic
crust to date, allowing study of igneous processes, and also alteration processes in rocks
that have never been below 150°C (other than briefly during drilling).
1C: A complete section from 15-200 mbsf through an oceanic detachment fault zone inserpentinised ultramafic rocks, and into less deformed rocks below, complemented bylogging and palaeomagnetic data for full structural re-orientation. Temperature
measurements will allow improved modelling of LCHF circulation.
1D: A new 80m Hole (U1309-J) at site AMDH-01 allowing calculation of the average strikeand dip of diabase intrusions already correlated between Hole U1309B and D (Fig. 6A)

Objective 1 hypotheses:
1E:

The proportion of ultramafic rock will increase as Hole U1309D is deepened reflecting
a gradual transition into mantle rocks; much of both the main gabbro and smaller bodies
to the south will show evidence of assembly by melt-rock reaction rather than discrete
intrusion.

1F:

Reaction porosity will be found on the margins of gabbroic intervals in contact withultramafics (blackwall zones) within the detachment fault zone, and will yieldformation waters distinct from Lost City vent fluids due to isolation from the main flow
system.

1G:

Deformation within the south wall fault zone will be multistrand, and strain will not be
focussed into shearing of serpentine but rather into tremolite-rich assemblages as seenin the cores from Exp. 357.

1H:

Isotopically heavy seawater-derived boron will not be present in the deep section ofHole U1309D, and may die out with depth in Hole AMDH-2A. Boron profiles willallow a better estimate of the boron content of slow-spread crust to be made than those
based on near-surface collected samples.

This objective will address IODP Science Plan Challenges 9, 10 and 14 (see also section 1)

2.2 Objective 2: Accessing the chemical kitchen preceding the appearance of life on
Earth: formation of organic molecules of prebiotic interest at high and low
temperatures
2.2.1 Scientific justification
It is axiomatic that before life could begin on Earth or other worlds in the solar system,
precursors of DNA, RNA, proteins and other biologically-relevant macromolecules must havebeen synthesised without biological intervention (Stüeken et al., 2013). One site where such
synthesis has been proposed are deep-sea vents such as the LCHF (Kelley et al., 2002; Martin
et al., 2008). Moreover, life relies on the use of chemical disequilibria that are widespread at
all scales in hydrothermal environments. LCHF is characterised by highly alkaline fluids
venting at 40-90°C, rich in H2 and CH4, and is hosted in serpentinite. Serpentinization andabiotic related organic synthesis reactions play a major role in generating H2 and organic C-species including methane, ethane, propane, small carboxylic acids such as formate, and aminoacids (Kelley and Fruh-Green, 1999; Kelley et al., 2002; Klein et al., 2013; Lang et al., 2010;
Lang et al., 2018; McCollom and Bach, 2009; McCollom and Seewald, 2013; Ménez et al.,2018; Proskurowski et al., 2008). Additionally, new paradigms are emerging for abiotic organic
synthesis in hydrothermal settings (Andreani and Menez, 2019). These are not CH4 centred,
but rather include the formation of compounds such as polycyclic aromatic hydrocarbons(PAHs) or carbonaceous matter, possibly mediated by minerals. Some reduced compounds,
such as methane and short-chain alkanes, are believed to form through Fischer-Tropsch-type
reactions at temperatures well above the known limit to life (Klein et al., 2019; Wang et al.,2018), perhaps catalyzed by Fe-, Ni-, and Cr-bearing minerals (Foustoukos and Seyfried, 2004).
The abiotic production of carboxylic acids, amino acids, PAHs, and carbonaceous compounds
likely proceeds at lower temperatures (< 400°C), including within thermal regimes conducive
to life (McDermott et al., 2015; Klein et al., 2019). For example, the abiotic synthesis of aminoacids and other organic heterocycles, presumably via a Friedel-Crafts-type reaction, hasrecently been documented (Fig. 8) in iron-rich saponitic clay from Hole U1309D samples(Ménez et al., 2018; Pisapia et al., 2018). The thermal limits of organic synthesis and diversityof products are uncertain, and the new continuous section in Hole U1309D from low
temperatures to 220°C will allow systematic investigation.
Recent work on Lost City fluids suggests that CH4 was generated at temperatures of around
300 °C, far above the current vent temperature (Wang et al., 2018). Fluid inclusions in gabbro
have been suggested as a significant source for abiogenic CH4 (Kelley and Fruh-Green, 1999,
2001). Secondary fluid inclusions in olivine have been shown to contain H2, CH4 and C2H6,
including in IODP Hole U1309B (Klein et al., 2019). H2 and hydrocarbons are suggested toform within fluid inclusions by reaction between fluid and olivine, or be inherited from earlier
reactions and trapped (Andreani and Menez, 2019). Carbon isotope ratios in the inclusions are
consistent with those in vent fluids (McDermott et al., 2015). New data from AM (Lilley, inprep) suggests that gabbros and troctolites contain higher concentrations of CH4 and heavier
δ13C than serpentinized peridotites, suggesting that gabbros, and not peridotites, are the likely
source of methane at LCHF. However, the pathways for methane formation and movement,
and the quantities involved, remain a pending question as is the diversity of abiotic organic
compounds that are formed in serpentinizing environments at both high and low temperatures.

While fluid inclusions could be an important source of H2 and CH4, it is unlikely they are theonly source. H2 is likely to be generated from reduction of H2O in any circumstance where theaverage Fe3+/Fe2+ of secondary minerals is higher than that of primary minerals (Andreani etal., 2013; McCollom and Bach, 2009), although experiments suggest generation rates arehighest around 300°C (McCollom et al., 2016). We hypothesise that gradients in H2 and CH4
may exist in the Massif due to diffusion of volatiles from depth.
2.2.2 Expected outcomesWe will sample H2 and organic molecules in fluid inclusions, in borehole fluids, and information waters in both the deepened Hole U1309D and at the new site AMDH 2A, using afull range of imaging and analysis methods (see Sampling Plan).
Objective 2 deliverables:
2A: Rocks of variable lithology sampled over the temperature range 147-220°C from1414mbsf to ~ 2060mbsf in Hole U1309D. Any organic compounds in these samples
will be of abiogenic origin since they have been above the limit for life throughout theirgeological history. Whole rock measurements will be complemented by formation fluid
sampling if sufficient porosity exists, and organic carbon imaging and in situ analysis inporosity and fluid inclusions. We will ensure sampling of any potential zones of fluid
flow, including fault zones and zones of more intense alteration, reaction porosity andveining.
2B: Systematic measurement of the Fe3+/Fe2+ ratio of secondary and primary assemblages
formed at all metamorphic temperatures and depths in the Hole, in order to assess sitesof H2 generation in the past and present, for which a single deep borehole is ideal.
2C: Samples at lower ambient temperatures (Holes AMDH-02A and U1309-J), thought to besuitable for the abiotic formation of organic compounds more diverse than hydrocarbons,
including formate and acetate and amino acids. We will seek these compounds information waters contained in reaction porosity and other permeable zones such as dyke
margins and fault rocks (Fig. 7). Together with U1309D core, we aim to establish a depth
limit for phyllosilicate-hosted amino acids and other types of organic compound.

2D: Place additional constraints on the carbon budget of AM via more systematic samplingthrough the detachment zone. Hole AMDH-2A will complement the sparse carbonate
vein findings of Expedition 357, targeting zones that might represent recharge zones for
LCHF fluids.
Objective 2 hypotheses:
2E: That gradients in H2 and CH4 will exist in vent fluids and fluid inclusions in plagioclase
and quartz (where these gases are unlikely to be generated in situ), indicating flux ofgases from depth. This hypothesis will also be tested by fluid sampling in the existing
Hole U1309D (this Expedition, and later in the entire Hole).
2F:

That if H2 and CH4 are in part generated in olivine-hosted fluid inclusions, different ratiosof gases (including mantle Helium) will be found in the fluid inclusions from the LCHF
vent fluids, reflecting mixing of different sources.

2G: That saponite and other iron-bearing minerals whose formation is accompanied by H2
production (e.g., hydrogarnets), will provide rich microsites for abiotic organic synthesis,
and that lithogical contacts and alteration zones may generate higher concentrations ofmore complex compounds due to enhanced chemical disequilibria.
Objective 2 will contribute to IODP Science Plan Challenges 10, 13 and 14. In addition, thiswork will be of great interest to astrobiologists investigating the likelihood of Life evolving on
Mars or icy worlds thought to host serpentinizing hydrothermal systems.

2.3: Objective 3: Deep biosphere and limits for life: controls of lithological substrate,

porosity and permeability, temperature, fluid chemistry and reactive gradients on
microbiology.
2.3.1 Scientific Justification

To date, there is very little information about the existence of a deep biosphere in subseafloor
serpentinizing systems. The warmest, highest pH domains of carbonate chimneys are
dominated by a single clade of Lost City Methanosarcinales (Schrenk et al., 2004). However
other microbial species reliant on possibly abiotic organic matter, have been found in the Lost
City vent fluids by DNA sequencing and lipid biomarker analyses (Bradley et al., 2009;
Brazelton and Baross, 2010; Brazelton et al., 2010; Brazelton et al., 2006; Méhay et al., 2013).

Prior to Expedition 357 it was hypothesised that mixing of diffuse hydrothermal fluids andseawater, together with organic rich zones related to serpentinization, would lead to a morediverse ecosystem (Frueh-Green et al., 2015), including both chemolithoautotrophs andheterotrophs. It was also hypothesised that serpentinizing environments would sustain higher
biomass than gabbro-dominated domains such as that sampled in Hole U1309D, where cellcounts were below detection limit, but gene sequencing revealed evidence for bacteria largely
related to hydrocarbon degraders (Mason et al., 2010).
Results from shallow (<16.4 mbsf) coring on the southern wall during Expedition 357
indicate a very low biomass ecosystem (Fig. 10) compared to other crustal subsurface systems(Früh-Green et al., 2018). However this coring did not reach target depths of 50-80m, and it isdoubtful that any part of the active Lost City flow system was accessed. Sampling probably
did not sufficiently target porous and permeable zones likely to contain more abundant biomass.
For example the highest cell count of 4.1 x 103 cells cm-3 was found in metagabbro (M0071A
2R1 66-86). This sample was taken adjacent to highly chloritized gabbro with relict reaction
porosity (Fig. 7), which was filled with chlorite down to conditions of <100°C, potentiallysuitable for microbe growth. There are a number of reasons why reaction porosity in mafic
lithologies may increase microbial activity, including lower local pH, nutrient access throughpermeability, and chemical gradients related to lithological boundaries and ongoing mineral
precipitation (Andreani and Menez, 2019; Lang and Brazelton, 2019). Operational restrictions
during Expedition 357 inhibited the ability to properly characterise the microbiology ofserpentinizing seafloor; deeper and more targeted samples are necessary to determine if there
are robust depth-, temperature- or lithology-driven patterns in the abundance or diversity of
microbial life, and if there are connectivities between this deeper ecosystem and that observed
at LCHF. Similarly, sample collection in Expeditions 304/305 was not targeted on porous,
permeable and reactive zones, (Mason et al., 2010) and may not be representative. We will
therefore drill a new single bit hole in the gabbroic domain (U1309-J) with the primary aim ofsampling known porous zones such as amphibole-filled vugs, the interior and margins of
diabase intrusions (Fig. 7), leucocratic veins, and fault breccias.
The thermal structure of AM also allows study of the temperature limits of deep biospherein a crustal system, as fluid temperatures in the existing Hole U1309D (Fig. 1) are expected tocross both the known upper thermal limit for life in laboratory cultures (122ºC) and the lowersuspected temperature limit (~80-90ºC) for life in energy-limited subsurface crustal systems(Heuer et al., 2016).

2.3.2 Expected outcomes:
Objective 3 deliverables:
3A: Fluid sampling for microbiology in Hole U1309D down to 1400mbsf. If the MTFS tool
is successful (see operations), we will collect up to nine samples at temperatures ranging
from 78 to 148°C (Fig. 10). Otherwise we will collect samples at 75-80°C with the Kuster
tool and additional samples at depths corresponding to 100, 120, and 130°C.
3B: We will leave Hole U1309D and AMDH-2A open as legacy holes for future fluid
sampling, temperature measurements, and potentially installation of equipment. The
thermal regime at AMDH-2A will yield vital information about shallow fluid flow
directions and permeability structure close to the LCHF, and the interaction betweenhydrogeology, the sources of components such as H2 and CH4, and microbiology, thus
linking to objectives 1 and 2.
3C: A microbiology sampling strategy focussed on porous and permeable zones in both
gabbroic rocks cut by diabase in Hole U1309-J, and in serpentinite containing gabbroand diabase intrusions close to the LCHF in Hole AMDH-2A.
Objective 3 Hypotheses:
3D: That a more diverse microbial biosphere will be found than in the LCHF chimneys.
3E: That higher cell counts (> 4 x 103 cellscm-1) will be found in porous and permeable zones
such as reaction porosity in the edges of gabbroic intrusions, fault rocks and fracturespotentially channelling Lost City fluids.
3F:

That higher cell counts and specific types of microbial life will be associated with local
fluid chemistry (including H2, CH4, organic acids, other organic compounds, cation andanion ratios and if possible pH, see Obj. 2C).

Objective 3 will address IODP Science Plan Challenges 5 and 6.

2.4: Drilling technology, new instrumentation and legacy
Achieving these scientific objectives will also have two important value-added benefits. First,
we will test the technological capabilities of the JOIDES Resolution’s coring, logging, andsampling program in ways that are highly complementary to the community aims of future“MoHole” drilling (M2M proposal 805-MDP and SloMo proposal 800-Full). There is great
current interest in deep drilling technology (Deep Crustal Engineering Working Group Rpt,2017) and it is important to determine coring rates in hot gabbros. Second, we will leave Holes
U1309D and AMDH-2A open for legacy operations, including fluid sampling and temperature
measurements, and potentially future installation of a CORK-Lite borehole observatory (Wheatand others, 2012) for continued sampling and monitoring.

3. Operational plan, challenges, opportunities and contingencies
3.1: Primary operational plan (Table 1, Fig. 11):
1. A new 200 m hole with ~15 m of casing and a re-entry funnel drilled-in using a mud
motor and under-reamer at site AHMD-02A. A camera survey and pilot hole arescheduled to assess conditions for casing. We intend to run plastic core liners andsynthetic tracers (perfluoromethyl decaline, PFMD) during drilling and coring to assess
sample contamination. This gently sloping location is ~100 m from Expedition 357 Site
M0069 (Fig. 3 and site form), which gave good recovery of diabase intrusives cutting
talc-amphibole-chlorite schist, a brittle fault zone at ~13 mbsf, and undeformed
serpentinites to 16.5 mbsf (Fig. 5). Proximity to the LCHF is necessary to address
Objective 1C. The target penetration is at least 200 mbsf to recover the entire
detachment fault zone (Objective 1).
2. Re-entering Hole U1309D (site AMDH-01A) for tool runs on the coring line to 1415
mbsf to collect fluid samples and temperature data. We target variations in fluid
chemistry related to lithology (olivine-rich vs olivine-poor), temperature, and potential
inflow of formation water along fault zones. A priority interval for sampling is theolivine-rich troctolites at 1100-1200 mbsf (Fig.1B), which are at roughly 100-125 ºC,
to assess differences in water-rock reactions (objectives 1, 2) and the thermal limits ofthe biosphere (objective 3). Tool runs will include:a. Several runs of the Kuster Flow Through Sampler (de Ronde et al., 2019) tocollect pristine borehole fluid samples 50 m above, at, and 50 m below theinferred fluid flow zone at 746 mbsf (~80ºC) for microbiological andgeochemical analyses (objectives 2 and 3).
b. One run of the new Multi-Temperature Fluid Sampler (MTFS; described in
more detail below) and the Elevated Temperature Borehole Sensor (ETBS;
maximum operating temperature of 232ºC de Ronde et al., 2019) to collect ~12
pristine borehole fluid samples at different temperatures and to determine thethermal profile of the borehole before drilling disturbance. The ETBS record
will confirm depth intervals where the MTFS collected samples, based on thetemperature ranges of the tool triggers.
c. If the new MTFS tool fails, the Kuster tools can again be run into the hole tocollect samples from deeper intervals prior to drilling. The tool is mechanicallytriggered with a clock and performs across the expected temperature range inthe hole.
d. If obstructions prevent the lowering of these tools, these sampling operations
would be canceled, to clean out the hole before the next operation. We do not
anticipate this issue, however, as Expedition 340T experienced good hole reentry conditions.
3. Re-entering the hole with a reverse circulating junk basket to retrieve small pieces of alogging tool lost during Expedition 340T (Expedition-340T-Scientists, 2012).
4. RCB coring in Hole 1309D for 9-10 bit runs to approximately 2060 mbsf (150-220ºCbased on the linear temperature gradient in the bottom 750 m of the existing Hole(Blackman et al., 2014)). Only gradual changes in lithology are expected fromgeophysics (Fig. 3). During Expedition 305, the Hole was deepened by 1014 m in 40
days on site. We have assumed slower drilling rates in hotter conditions, down to 1m/hr
below 2000 mbsf, and half-length RCB cores to account for challenging penetration
conditions (Table 1). Core barrels will run without core liners (plastic liners begin tomelt at 80ºC and aluminium split cores are only marginally useful), with the contents
shaken out into split core liners upon recovery, as done on the Brothers Arc Expedition
376 (de Ronde et al., 2019).
5. Logging (with flasked tools to protect electronics from high temperatures) from 1300
mbsf to as deep as temperatures allow. Depression of borehole temperatures during
drilling and hole conditioning should allow a high proportion of the deepened hole tobe logged. A first standard Triple Combo logging tool string run would chart holeconditions (caliper) while logs of density (HLDS tool) and resistivity (HRLA tool) will
be most valuable for wall rock characterization. The Formation MicroScanner (FMS)Sonic tool string would be run next to image structural features, document fractureorientations, and measure wallrock seismic velocity. If time and circumstances allow(i.e., no marine mammals in the area), we would also run the Vertical Seismic Imager(VSI). This will generate extended crustal architecture logs for synching with new
lithological analysis of deep, hot gabbros (objective 1).
6. A new 80m RCB Hole (“U1309-J”) at Site AMDH-1A aimed primarily at samplingporous zones in gabbro and diabase for microbiology and porewater chemistry.
7. Returning to Site AMDH-02A to assess if fluid flow is occurring, measure temperatureand log the Hole with the same tools as (5) above.
Based on communication with the JOIDES Resolution Science Operator (JRSO, Table1), conservative estimates for this expedition are 61 days including transit. We have notincluded a general contingency allowance. Operational delays could be absorbed by leaving
logging at Site AMDH-02A as a legacy operation, and by cutting the last two bit runs (6days) from IODP Hole 1309D (table1), losing only 80 m of penetration, such that objectives
would not be seriously compromised.
3.2: Contingency plans (Fig. 11):
Contingency 1: The most extreme contingency is required if the re-entry cone for Hole
U1309D is dislodged so that the Hole cannot be deepened or sampled for fluid. In this case,our backup plan would be drill Hole U1309-J, and then to resume operations at Site AMDH02A but extend the total penetration depth as far as possible. Assuming 35 days (Table 1) anda relatively slow average penetration rate of 2m/hr, this would allow deepening to ~ 1000m.
Based on the FWI image on site Figure AMDH-02A, the Hole would pass through an inversion
in the P-wave velocity which dips north and leads towards the LCHF. We speculate that thismay be a fault-controlled hydrothermal feeder zone, perhaps controlled by a larger gabbroic
intrusion above. This contingency plan would:Allow deliverables and hypothesis tests 1D, 1F, 1G and 1H (in part) still to be achieved,and enhance objective 1CAllow deliverables and hypothesis tests 2B, 2C, 2D, 2E (part) 2F and 2G to be achievedor expandedAllow all the microbiology deliverables and hypothesis tests except 3A and part of 3B
to be enhanced by additional sampling in the zone of potential subsurface biosphere.

A new objective to significantly enhance groundtruthing of the Full Waveform inversion (Fig.
3B, C) would be achieved. This area is characteristic of the 'Intermediate Velocity' material
identified by Canales et al. (2008) and Henig et al. (2012). Ground-truthing this interpretation
is useful as current models of OCC structure and evolution depend on itContingency 2: If neither Hole U1309D deepening or AMDH-2A coring are possible, wewould establish a new re-entry hole at alternate site AMDH-03A, 2 km west of and ~400 m
downslope of AMDH-02A (Figure 3) This site is between Exp. 357 sites M0070 (carbonate
rich breccias) and M0071 (serpentinite with chloritized metagabbro containing reaction
porosity). It shows similar velocity variations in the FWI image to site AMDH-2A (Harding etal., 2016) (site Form AMDH-3A and Fig. 3). At this site we can achieve all the objectives listed
in contingency 1 except that temperature measurements (Obj. 1C) would not constrain thethermal structure around the LCHF as well.
Contingency 3: If we are unable to place casing and a re-entry cone at either site AMDH-2A
or AMDH-3A, we propose to drill single bit Holes close to as many of the Exp. 357 shallow
holes as time allows. We consider the geophysics to be sufficiently indicative of the generalconditions in this area that for a single bit Hole the bathymetry available from the 50 m
multibeam bathymetry collected on Exp. 357 (Früh-Green et al., 2018), together with seabed
conditions via a camera survey will be sufficient to site Holes. We would avoid drilling closer
than 100m to sites with unsampled borehole plugs (M0068 and 75), and also sites with somedrilling hardware left in them (M0069A, 71C and 76B). This would allow most of theobjectives of the expedition to be achieved with the probable exception of a full section throughthe detachment fault zone, temperature measurements and fluid sampling. Only modest
surficial groundtruthing of geophysics would be possible.
3.3: Other considerations:
Achieving objective 1 requires collection of deep gabbros, which we anticipate to vary in insitu temperature from 150ºC to 220ºC . During IODP Expedition 376 at Brothers Arc, drillingand coring operations were possible up to 260ºC (de Ronde et al., 2019) thus, operationally,
achieving this objective is feasible.
Collection of hot, pristine fluids (up to 150ºC) of ~600 mL volume with the Kuster tool was
proven on Expedition 376 (de Ronde et al., 2019).
Improved fluid sampling is reliant on the use of the new Multi-Temperature Fluid Sampler(MTFS, Fig. 10), designed and built by proponent Geoff Wheat and colleagues (NSF award
OCE-1830087). The MTFS uses a trigger mechanism based on change of a shape-memory
alloy that is activated at a specific temperature range (details not provided as the method isunder review for a provisional patent). Twelve ~ 1L units were built for IODP Expedition 385T,
but a stuck packer could not be removed from Hole 504B, preventing deployment and trial of
the MTFS. However, laboratory tests have confirmed the temperature ranges of the available
triggers up to 183ºC, and shipboard operations during 385T allowed detailed planning with the
rig floor on how to deploy the tool in combination with the ETBS. Figure 10B presents an
overview of the depth ranges for fluid samples that could be captured by the existing MTFS
samplers, as well as the target depths for preliminary Kuster tool runs.

4. Sampling and analysis plan
4.1: To achieve objective 1, rock samples will be studied by the full range of hard rockmethods; optical and SEM observation, EMPA, XRD, major and trace whole rock analysis(including in situ methods), palaeomagnetic analysis, radiometric dating of zircons and fluidinclusion analysis, and analysis of radiogenic and stable isotopes (see also objective 2).
Petrophysical properties of the deep section will be documented.
We will ensure that unwanted pieces (e.g. the outside) of whole round cores removed for
microbiology and other analyses are returned as soon as possible to be available for description,
analysis and archiving. If samples are broken up on board ship we will involve members of therock description teams in assisting in this process in order to preserve way up and other data.
If they are broken up at a later date we will take steps to archive them properly in the core
repository.
4.2: High temperature core samples: To achieve objectives 1 and 2, we will core hot (>150ºC)
rocks at Hole U1309D that have never been cold (other than briefly during drilling), but whichhave been affected by gradual geological cooling with limited fluid access. We are keen to
avoid any contamination, degradation or changes in the mineralogy of selected samples prior
to analysis. Serpentinites can oxidise rapidly in a moist, ambient atmosphere at room
temperature, with likely effects on organic molecules and the oxidation state of the sample. It
will be impossible to limit sample contamination during coring above 147ºC using normal
microbiology protocols (i.e., core barrels are run without plastic core liners that begin to melt
at 80ºC, synthetic tracers commonly used for contamination tracing volatilize at thosetemperatures). We have not yet finalised protocols in this area. Options include:
1. Cleaning whole round samples and storing under inert, dry conditions:
Immediately after shaking out the contents of the core barrel into fresh split core liners,
photographing and measuring the core pieces, we will remove a small fraction (<5%core section) of the whole round core (WRC) and immediately transfer it to theChemistry/Microbiology lab for storage preparation. This will involve rinsing thesample with nitrogen-sparged filtered seawater (to remove potential microbial
contamination) and gently drying under a stream of filtered nitrogen, transferring it togas-tight plastic-lined aluminium bag (as commonly used with anoxic sediment coreWRC), flushing the bag and sample with nitrogen headspace before impulse sealing.
Samples may be broken up using a titanium chisel for shipboard work.
2. Cleaning samples as above and then storing in ovens at a temperature close to thesample depth in Hole: This may prevent low temperature reactions and samples may
be useful for further work such as fluid-rock interaction or microbial culturing.
Container materials such as aluminium and Teflon may catalyse reactions or themselvesdegrade, particularly at high temperature (Andreani and Menez, 2019).
3. Critical point drying to preserve organic compounds. This would need to beestablished in the Microbiology Laboratory
Further tests are needed to establish what measures will best protect the samples. If the
Expedition is scheduled we will develop detailed protocols in collaboration with JRSO.
Different subsamples may be treated in different ways to allow comparison.
To characterise organic compounds in rock core, a subset of samples will be analysed using
Synchrotron Fourier Transform Infrared (FTIR) imaging to characterize organic molecules in
microscale porosity (Ménez et al., 2018; Pisapia et al., 2018). This will be complemented with
Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) and Time of

Flight secondary ion mass spectrometry (TOF-SIMS) imaging and SEM analysis. In situ
observations in core will give control information on what compounds, both organic andinorganic, are actually produced at temperatures >140°C in young (<1.2 Ma) gabbroic rocks
which have never been at lower temperature. If sufficient hot material is available, some of thesamples could be used for incubation experiments to examine microbial colonization of crustal
material that has never been exposed to life, following approaches used with sterilized rocksubstrates in other warm deep biosphere environments (Ramírez et al., 2019).
4.3 Low temperature rock sampling: Achieving objectives 2 and 3 requires removing WRCfrom the southern wall hole (AMDH-02A) core sections immediately after collecting and initialcataloguing to prevent organic geochemical and microbiological contamination, as has been
done on recent expeditions (de Ronde et al., 2019; Hickok et al., 2018; MacLeod et al., 2017).
We will process the samples either within HEPA-filtered “KOACH” workstations (to minimize
particle/cell contamination) and/or inside anaerobic chambers (to minimize oxygen exposureof anoxic samples) in the Chemistry/Microbiology laboratory after initial removal of WRC
from the core splitting room. We will use similar types of contamination control, geochemical,
and microbiological samples as was done on previous expeditions (de Ronde et al., 2019; FruhGreen et al., 2017), with an emphasis on high resolution sampling for rock crushingexperiments to examine fluid inclusion gas contents. We will also recover fluids and microbial
samples from larger scale reaction porosity and fault zones, using modified methods for fluidinclusion crush-leach analysis to analyse cations (Banks and Yardley, 1992), halogens andisotopes (McCaig et al., 2000), together with organic acids and other organic compounds(Albert and Martens, 1997).
We will sample for the full range of microbiological techniques as conducted on recent hardrock expeditions (de Ronde et al., 2019; MacLeod et al., 2017), including ATP analysis, cellcounts, viral analysis, cultivation experiments and molecular biology.
4.4: Borehole fluids: Experience gained from recent expeditions (i.e., 360, 376, 385T) will
guide protocols for processing of borehole fluid samples for microbiological and geochemical
characterization (objectives 1, 2 and 3). Prior to deployment, fluid tool sampling surfaces will
be cleaned with detergents (to remove grease), dilute bleach (to kill any surface-attachedmicrobes), dilute acid (to remove any leachable metals), distilled water (to remove all of theabove), and alcohol solutions (to remove remaining organics and for final sterilization before
deployment). Upon recovery, fluid samples will be split for standard ship-based dissolvedsolute measurements and a variety of shore-based analyses including cell density
measurements, flow cytometric-based cell sorting and subsequent DNA sequencing, possible
culturing experiments, dissolved inorganic and organic carbon concentration and isotopic
composition measurements, and isotopic analysis of dissolved solutes (Li, B, Ca, Mg, Sr).
These analyses will be conducted to better understand phase equilibria and rock-fluid
interaction processes as well as deep biosphere microbial activity and structure. Fluid
composition data and fluid-rock interaction will be modelled as described in section 2.1.1.4.

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Table 1.
Atlantis Massif (P937)
Operations Plan Summary Slimmed
m idgley, 27 Septem ber 2019

Site No.

Location(Latitude
Longitude)

Seafloor Depth(mbrf)

Barbados
AMDH-02A

U1309D

AMDH-02A

30.131700° N
42.1202° W

30.168658° N
42.1186° W

30.131700° N
42.1202° W

Transit(days)

Operations Description

Begin Expedition
836

1656

836

5.0

Transit 1409 nm i to Site AMDH-02A @ 10.5 knots
Hole A: Seafloor Survey for Hole A and pilot hole
Hole B: Reentry system for Hole B
Hole B: Coring Bit Run #1 - to 100 m bsf
Hole B: Coring Bit Run #2 - to 200 m bsf
Sub-Total Days On-Site:

5.6
1.5
1.6
2.1
2.1
7.3
0.0

Transit 2 nm i from Site U1309D to Site AMDH-02A @ 8.9 knots
Hole B: Logging and sam pling at AMDH-02A

0.0

End Expedition
Port Call:
Sub-Total On-Site:

5.0
46.6

1.0
0.8
3.3
3.3
3.4
3.4
3.3
3.2
3.3
3.3
3.0
3.4
1.8

1.5

0.5

0.8

43.3

3.3

1.2

Transit 936 nm i from Site AMDH-02A @ 10.5 knots

Ponta Delgada

LWD/M
WD Log(days)

Port Call Days

Transit 2 nm i from Site AMDH-02A to Site U1309D @ 8.9 knots
Hole D: Fluid Sam pling and tem perature logging
Hole D: Fish Caliper w ith RCJB at U1309D to 1415.5 m bsf
Hole D: Bit Run #1 - to 1495.5 m bsf - 2 m /h penetration rate
Hole D: Bit Run #2 - to 1575.5 m bsf - 2 m /h penetration rate
Hole D: Bit Run #3 - to 1655.5 m bsf - 2 m /h penetration rate
Hole D: Bit Run #4 - to 1735.5 m bsf - 2 m /h penetration rate
Hole D: Bit Run #5 - to 1800.0 m bsf - 1.5 m /h penetration rate
Hole D: Bit Run #6 - to 1860.0 m bsf - 1.5 m /h penetration rate
Hole D: Bit Run #7 - to 1920.0 m bsf - 1.5 m /h penetration rate
Hole D: Bit Run #8 - to 1980.0 m bsf - 1.5 m /h penetration rate
Hole D: Bit Run #9 - to 2020.0 m bsf - 1.0 m /h penetration rate
Hole D: Bit Run #10 - to 2060.0 m bsf, log w ith triple com bo, FMS sonic and VSI
Hole U1`309-J: RCB coring to 80 m bsf
Sub-Total Days On-Site:
38.1

Sub-Total Days On-Site:

Drilling
Coring(days)

3.7

9.3
Total Operating Days:
Total Expedition:

56.0
61.0

A

B

Figure 1. A: 3-D perspective view of the Atlantis Massif showing the main structuralfeatures, the location of the Lost City Hydrothermal Field (LC), and the main sites drilled in
Expedition 357. The main two drilling locations proposed here are shown by white dots.
From Früh-Green et al. (2018). B: Lithology, temperature and resistivity logging resultsfrom Expeditions 304/305 and 340T (from Blackman et al., 2012). ΔT is the difference
between the observed temperature and an extrapolation of the conductive gradient at depth
to the surface. Minor excursions in temperature are interpreted as zones of fluid flow at 746
mbsf, where the temperature gradient changes from convective to conductive, and at 1107
mbsf, near the zone of olivine-rich troctolite.

Figure 2. Conceptual sketches of the tectono-magmatic evolution of a heterogeneous
lithosphere and denudation of mantle rocks as detachment faulting progresses. A: Generic“detachment mode” seafloor (Escartin and Canales, 2011). B: The southern wall isdominated by variably altered peridotites with gabbroic lenses (Boschi et al., 2006) At thesummit is a 100m thick detachment fault zone containing talc-tremolite-chlorite metasomatic
schists (Karson et al., 2006) C: in contrast, major gabbroic intrusions dominate the central
dome (Grimes et al., 2008)

Figure 3: Seismic crossing lines and seismic velocities across the Atlantis Massif. A:
orientation of crossing lines in relation to previously drilled locations and primary andalternate sites of this proposal. (inset map shows relative locations of existing Holes at Site
U1309, and proposed Hole U1309-J) B: full waveform inversion (FWI) of multichannel
seismic (MCS) P-wave velocities along seismic line Meg4 (from Harding et al., 2016), withthe two primary sites indicated. C: FWI of MCS line Meg9 showing alternate site AMDH-3A
D: Tomographic inversion of Ocean Bottom Seismometer (OBS) velocities along refraction
line 8 that crosses near Hole U1309D, showing expected continuation of P wave velocities
between 6 and 7 km/s in the deepened Hole.

Figure 4. Summary of igneous compositions in Hole U1309D (Godard et al., 2009) and in IODP
Expedition 357 core samples (from Früh-Green et al., 2018). Note the very primitive compositions ofmany of the gabbroic rocks compared to the diabase dykes, which are similar to MORB at 30° N in
the AtlanticFigure 5. Lithological summaries from IODP Expedition 357 Holes along the southern wallof AM, focusing on the central and eastern sites (from Früh-Green et al., 2018). Our
proposed primary southern wall site AMDH-02A is close to Hole M0069A, where
metadolerite intrudes into talc-tremolite-chlorite schists, which are brecciated and underlain
by a sub-horizontal brittle fault zone at ~13 mbsf. Below this fault are little-deformed
serpentinized harzburgite and dunite. Beneath the soft sediment layer, recovery in the Holewas excellent.

A

B

Figure 6. A: Interpretation of the geology at Site U1309 after 1 bit run in Hole U1309D(drawn by Michael Abratis). Diabase intrusions interpreted as sills within a heterogeneous
fault zone cutting multiple gabbroic intrusions. Arrows indicate fluid pathways B: Proposed
structure of the detachment zone at Site U1309 before rotation of the fault into the current
sub-horizontal orientation(McCaig and Harris (2012). The fault zone is interpreted as athermal boundary layer between gabbroic melt and hydrothermal circulation in the fault zone
and hangingwall. Similar diabases occur in some of the Exp 357 cores chilling against
serpentinites, talc-tremolite-chlorite schist and fault breccia, and occurring as clasts in
breccia (Fig. 5). In our new Hole AMDH-02A we expect to sample a similar sequence of fault
rocks and syntectonic intrusives, but in predominantly serpentinised peridotite, not gabbro.

Fig. 7: Reaction porosity in the Atlantis Massif. A: amphibole filled vug in gabbro with bleachedreaction rim of sodic feldspar and minor amphibole, 72mbsf in IODP Hole 1309B. Relict porosity iscommon both in the vug and the reaction rim. The vug is interpreted as a section through astockwork pipe for black smoker fluid flowing up the detachment fault. B: Fibrous amphibole filling
porosity formed by dissolution of clinopyroxene in diabase, IODP Hole 1309B. C: chloritized gabbrowith plagioclase completely dissolved and the space filled by chlorite, Exp. 357, Hole M0071A. D:
chlorite geothermometry (Bourdelle and Cathelineau, 2015) showing that the vugs filled over atemperature range from 400 to <100 °C

Lost city

rotronUVscenceto thence ofcyclesng
phan…

Figure 8. Endogenous UV-autofluorescence locally revealed by synchrotron deep ultraviolet (S-DUV)
imaging of a highly altered mantle-rock recovered at 173.15 m below sea floor from IODP Expedition
304 Hole U1309D (Ménez et al., 2018). UV-fluorescence emerged from heteroatomic aromaticcompounds shown to be spatially restricted to an Fe-rich clay in which they are heterogeneously
distributed. From top to bottom: Optical image showing yellow to brownish phases identified as Ferich serpentine (Fe-Srp) and Fe-rich saponite (Sap), hosted in a serpentinized harzburgite witholivine being replaced by magnetite (Mag) and serpentine exhibiting a characteristic mesh texture(mesh Srp); the green arrow indicates sample orientation. Below is full field S-DUV image of the area
depicted above by the light-green rectangle, collected between 400 and 440 nm using excitation(λexc) at 275 nm. AU, arbitrary units. At the bottom is the fluorescence emission spectra collectedwith excitation wavelengths of 250, 275 and 310 nm at the location shown by an asterisk in the DSUV fluorescence map. The spectra collected at 250 and 310 nm do not show a notable UVautofluorescence signal, whereas the spectrum at 275 nm displays fluorescence characteristic ofindole at 340 ± 6 nm, tryptophan at 358 ± 3 nm, skatole at 380 ± 3 nm, and hydroxyanthranilic acid at
403 ± 3 nm18 (mean ± s.d. of three independent fits performed on three areas). Also shown are afluorescence emission spectrum collected at 275 nm in the Fe-rich serpentine and the typical emission
spectrum of a biological cell showing maximum fluorescence emission, mainly arising from proteinforming tryptophan, shifted to 335 nm21. The orange area represents the fluorescence detection
range.

Figure 9. Cell densities in samples collected from the southern wall of AM during Expedition
357 show the very low biomass levels in shallow, highly altered serpentinites (from FrühGreen et al., 2018). The shaded region shows the range of counts below the minimum
quantification limit (MQL) of 9.8 cells cm-3. Two deeper sediment samples (Sed) from Hole
M0069A had higher cell densities than most of the rock core samples. The highest bedrock
cell density of 4.1 x 103 cells cm-3 was found in metagabbro from M0071A 2R1 66-86. This sample
was taken adjacent to highly chloritized gabbro with relict reaction porosity (Fig. 7)

Fig.10 A: The Multi-Temperature Fluid Sampler (MTFS) assembled and ready for
deployment on the catwalk during IODP Exp. 385T. Photo by Geoff Wheat. B: Estimatedtemperature and depth ranges for fluid sample collection in Hole U1309D with the newMulti-Temperature Fluid Sampler (MTFS; Geoff Wheat, unpublished data), as well as
estimated locations of Kuster Tool fluid sample collections, in comparison to lithology
and temperature logs from Hole U1309D from Expeditions 304/305/340T (Blackman etal., 2011, 2012). Small temperature excursions occurred at ~100, ~ 750 and ~ 1100 mbsf
suggesting fluid influx (see Fig. 1B).Temperature ranges of the MTFS triggers are basedon several (n=3+) laboratory tests of each trigger (Geoff Wheat, unpublished data). Notethat in Exp. 340T, the maximum temperature was 146.2 C at 1405 mbsf. We will leave thefinal SMA sampler on the string in case the temperature is higher after another 9-10
years of equilibration since Exp. 340T.

Figure 11: Decision tree for drilling operations. Primary plan (Table1) is in black. Various
alternate plans at different stages in the proposal are shown. Only failure to re-enter Hole
U1309D would necessitate a major change in plan. On JRSO advice we have not included a
specific contingency, but some loss in penetration in Hole U1309D at Site AMDH-01 could
be accommodated without major harm to the objectives.
Note that in our final contingency we request permission to drill single bit Holes anywhere
within the Exp.357 footprint. The main criteria for siting would be closeness to Exp.357
Holes, and seabed conditions from camera survey including low slope angle. Geophysicalconditions in the top 100m are similar everywhere, and there is no probability of hazards
such as clathrate

IODP Site Forms

937 - Full

Form 1 – General Site Information

2

Section A: Proposal Information

Proposal Title

Date Form Submitted

Accessing the Building Blocks of Life: Deepening Hole U1309D, Atlantis Massif, Mid-Atlantic Ridge

2019-10-10 17:10:16

Site-Specific (i) Sample fluids and measure temperature in existing Hole 1309D down to 1414 mbsf (expected temperature
Objectives with 225 centigrade). (ii) Deepen existing Hole U1309D by ~650 m and collect samples for petrology andgeochemistry of abiotic organic compounds and H2; (iii) log Hole with flasked tools. (iv) Drill new 80m HolePriority

20-30 m north of Hole U1309D, for microbiology sampling of porous rocks, fault zones, and correlation with(Must include general
Holes U1309B and D. This Hole is designated "U1309-J" in the text and site form. Note that Hole 1309C
objectives in proposal)
with protruding casing needs to be avoided.

List Previous
Drilling in Area

Expeditions IODP 304, 305 and 357

Section B: General Site Information

Site Name:
If site is a reoccupation of an
old DSDP/ODP Site, Please
include former Site#

U1309D

Latitude:Deg:

Longitude:

Deg:

Jurisdiction: none

30.1687

Distance to Land:(km)-42.1186

Coordinate System:
Priority of Site:

Area or Location: Atlantis Massif, Mid-Atlantic Ridge

AMDH-01A

WGS 84
Primary:

Generated: 2019-10-11T00:26:09+00:00✓⃞

Alternate:⃞

Water Depth (m): 1656

Section C: Operational Information
Sediments

Basement

0660

Proposed
Penetration (m):Total Sediment Thickness (m)2

Total Penetration (m):General Lithologies:
Coring Plan:(Specify or check)gabbro, serpentinite

unconsolidated
Continuation of Expedition 305 coring. Multiple re-entry
Additional single bit Hole West of U1309D, termed "U1309-J"
APC

Wireline Logging
Plan:

660

XCB

RCB

Standard Measurements

Special Tools

✓
✓
✓
✓
✓
✓
✓

Magnetic Susceptibility

WL
Porosity
DensityGamma Ray
Resistivity
Sonic (∆t)
Formation Image (Res)

Borehole Temperature✓✓

Re-entry✓

Other
tools:

Fluid sampling hopefully using new
MTFS tool. Also the 3rd party Kuster
tool. For temperature the ETBS tool isrequested.

Formation Image(Acoustic)PCS

VSP (walkaway)
LWD

VSP (zero offset)
Formation Temperature& Pressure
Other Measurements:

Estimated Days:

Drilling/Coring:

Fluid sampling

Logging:38

2

Total On-site:

40

Observatory Plan:

Longterm Borehole Observation Plan/Re-entry Plan

Potential Hazards/
Weather:

Shallow Gas

Complicated Seabed
Condition

Hydrothermal Activity

Preferred weather window

Hydrocarbon

Soft SeabedLandslide and Turbidity
Current

December to May,
avoiding Atlantic
hurricane season

Shallow Water Flow

Currents

Gas Hydrate

Abnormal Pressure

Fracture Zone

Diapir and Mud Volcano

Man-made Objects

Fault

High Temperature

H2S

High Dip Angle

Ice Conditions

Casing with re-entry cone already in place.Hole has been re-entered many times. Hole should be left
clear for future logging and fluid sampling.

(e.g., sea-floor cables,
dump sites)✓

CO2
Sensitive marine
habitat (e.g., reefs,

none

vents)

Other:

Generated: 2019-10-11T00:26:09+00:00

maximum predicted temperature is 225 C at 2100 mbsf, based on gradient in the lower 750 m ofHole U1309DIODP Site Forms

Proposal #:937 - Full 2

Form 2 - Site Survey Detail

Site #:

AMDH-01A

Date Form Submitted: 2019-10-10 17:10:16

Data TypeIn SSDB

1a High resolution seismic reflection (primary)no1b High resolution seismic seismic reflection (crossing)no2a Deep penetration seismic reflection (primary)yes

Line: Meg4
Position: Meg4 , CMP 4145 closest, ~400 m to east; RP#3378 closest in
meg4_stack_2400_5280.segy

2b Deep penetration seismic reflection (crossing)yes

Line: Meg10
Position: Meg10, ~1.8 km north, CMP 2405 close perpendicular projection

3 Seismic Velocity

yesHarding et al. 2016- Meg4 waveform inversion & updated checkshot datafrom borehole; Blackman et al. 2014- complete sonic log to ~1400 mbsf.
(older versions Canales et al. (2008) and Henig et al. (2012) Meg4
downward continued streamer tomography, former to datum above
seafloor and latter to seafloor)

4 Seismic Gridyes

Meg4, Meg5, Meg6, Meg9, Meg10- Canales et al., 2004 (Meg8 outside
corner)5a Refraction (surface)yes

OBS refraction- Blackman and Collins 2010; Line 9a crosses Site; Line 8
is 1.8 km to N

5b Refraction (bottom)

yes

NOBEL- Harding et al. 2016 waveform inversion for Line 10, just north ofhole
Collins et al. 2009 shows older tomography for Lines 9 & 10.

6 3.5 kHzno

7 Swath bathymetryyes

8a Side looking sonar (surface)no8b Side looking sonar (bottom)

yes

CD100 Tobi MARVEL2000 DSL120

9 Photography or video

yes

MARVEL 2000 Alvin and Argo images

10 Heat Flowyes

Temperature throughout borehole; from deep section heat flow prediction
is 257 mW/m2, Blackman et al., 2014

11a Magnetics

yes

11b Gravity

yes

12 Sediment cores

yes

Holes U1309A, U1309E, U1309F, U1309G

13 Rock samplingyes

CD100 Dredge, MARVEL2000 Alvin; Hole U1309D core to 1415mbsf

14a Water current datano14b Ice Conditions

no15 OBS microseismicity

no16 Navigationyes

17 Otherno

Generated: 2019-10-11T00:26:09+00:00

Details of available data and data that are still to be collected

CD100 EM12, MARVEL2000 SeaBeam2000, 100-m regional gridBlackman et al., 2008. EM120 20-50m grid Früh-Green et al., 2017.

Pariso et al., 1996; MARVEL2000 deep-tow

Blackman et al . 2008

1 yr study, Collins et al. 2012

MCS, OBS & NOBEL refraction, DSL120, Alvin rock sample & dredge
locationsIODP Site Forms

Proposal #:937 - Full 2

Form 4 - Environmental Protection

Site #:

AMDH-01A

Date Form Submitted: 2019-10-10 17:10:16

Pollution & Safety Hazard

Comment

1. Summary of operations at sitevisual check for flow; re-enter; slow down-run for minimally-perturbed T measure; up run for caliper& (initial) borehole fluid sampling; additional fluid sampling to cover desired intervals (if dont havemulti-sample capability); RCB coring; logging of at least newly-penetrated section, full section iftime.

2. All hydrocarbon occurrences based on
previous DSDP/ODP/IODP drillingnone

3. All commercial drilling in this area that
produced or yielded significant
hydrocarbon showsnone

4. Indications of gas hydrates at thislocationnone

5. Are there reasons to expecthydrocarbon accumulations at this site?

none

6. What "special" precautions will betaken during drilling?

minimal disturbance in hole until initial T measurement & fluid sampling are complete. During final
logging temperature needs to be monitored to avoid damge to temperature-limited logging tools

7. What abandonment procedures need
to be followed?

standard for tool stuck in hole, if that were to occur

8. Natural or manmade hazards which
may affect ship's operations~20m casing was left protruding from seafloor at Hole U1309C in 2004

9. Summary: What do you consider the
major risks in drilling at this site?

moderately high temperature as hole deepens (~150-250 °C expected)

Generated: 2019-10-11T00:26:09+00:00

IODP Site Forms

Proposal #:Form 5 - Lithologies

937 - Full 2

Site #:

AMDH-01A

reflectors,
Subbottom Key
depth (m) unconformities,
faults, etc

Age (My)

Assumedvelocity(km/s)

Lithology

0 - 150~1.2 Marocks

3.5

few m of fault
zone,
metadiabase,metagabbro

detachment zone

350 - 380

highly altered rock,likley reflector
source5.3

olivine-rich
troctolite, trotolite,
gabbro750 - 750

(paleo) fault

5

fault gouge,
diabase1080 1200

portions highlyaltered, possible
reflectors

5.8

oliveine-rich
troctolite(serpentinized)
interfingered
gabbro4000 4000

green reflector
Meg4

6.9

base gabbro?

Generated: 2019-10-11T00:26:09+00:00

Date Form Submitted: 2019-10-10 17:10:16

Paleo-environment

Avg. accum.
rate (m/My)

Comments

n/a

upper 20 m cased.
Age from Grimes et al(2008) applies towhole section
reflectivity modelingby Collins et al., 2009velocity control by
waveform inversion,
304/305/340T
checkshots, sonic log(Harding et al. 2016)

Harding et al 2016

M eg 4

97
22
05

01

97

30

31

05

01

97

05

01
25

25

27

28

28

MCS
Meg10

U1311A,B

4097

4001
3905

01
19

05

97
19

M0068

21

01

97

3401
M0076

22

05
24

97

AMDH−02AM0072

22

M0071

01

3497
M0069

M0073

25

05

3605

25

05

97

01
28

27

30.1333˚

30

AMDH−03A

3701

M0070
28

01
31

05

331209
97

33

97

01
34

36

05

3797

34

97

01
37

37

05

4301 U1309G,H
ORB2
4205

M0074

C protuding casing
A/B
39

U1309FU1309A−E

AMDH−01A

N

30.15˚

M0073

Exp 304
Lost City
MCS Line
w/CMP#

4505

24

22

0

U1309FExp 357

4601

Meg5

E

AMDH-1A
D

4697

4397

NOBEL
1

-J
30.1667˚

97

M eg 6

OBH25

10 m

Line Meg 4 Stack

NOBEL
9

OBH16

Site 1309, Hole U1309_

01
22

97

05

30.1833˚

21

4

19

OBS
Line 8

05

3

19

30.2˚

18

(Harding et al. 2016)

2

01

IODP 937 Full-2, Site Figure AMDH-01A
1601

N km/s16
97

MCS Line Meg 4
Waveform Inversion

H MD
A

13
97

9D
30 A
U1 -01
H

15
05

1

ole

12

D
AM

13
0

Depth (km)

2A

H-0

S

Meg9

3305

30.1167˚Interpreted Reverse Time Migration(Harding et al. 2016)−42.2˚−42.1833˚

5.25 km/s
contourbase
gabbroic
body?

1

OBH16

OBH25

ORB2

OBH22

ORB1 OBS50

OBH26

central dome

outsidecorner

AMDH-01A projection

depth (km)Depth (km)crustmantletransition
zone?

OBS64

rift
axis

7
6
5

5

4
3
2

Blackman & Collins, GRL 2010

10
-20

-10

0

10

distance (km)20−42.15˚−42.1333˚
meters−5000

0 Line8b−42.1667˚velocity(km/s)

−4000

−3000

−2000

−42.1167˚−42.1˚

−42.0833˚−42.0667˚

25-m contour interval, 100-m heavy−1000

Uninterpreted, zoomed , Reverse Time Migration
Hole U1309D (solid), AMDH-01A (dash)

2
3
4

5
Refl.
Pt # 3000

3500

4000

MCS: meg4_stack_2400_5280.segy (correct nav), meg4migrated.segy (needs nav),meg4.cdp_nav_bt_twtt
Refraction: obs64ch*n08.segy, obh16n8r.segy, obh25n8r.segy, orb2n08.segy,
obh22n8r.segy, orb1n08.segy, obs50ch*n08cor.segy, obh26n8r.segy

IODP Site Forms

937 - Full

Form 1 – General Site Information

2

Section A: Proposal Information

Proposal Title

Date Form Submitted

Accessing the Building Blocks of Life: Deepening Hole U1309D, Atlantis Massif, Mid-Atlantic Ridge

2019-10-10 17:10:16

Site-Specific 200mHole with re-entry. Complete section through detachment fault zone in serpentinized peridotite. Sample
Objectives with for deformation, alteration, igneous petrology, microbiology and organic/inorganic geochemistry. Log fortemperature and other properties. Legacy Hole for sampling fluids and gases, establishing temperature
Priority(Must include generalobjectives in proposal)

List Previous
Drilling in Area

profile, potential instrumentation

IODP Expedition 357, IODP Expedition 304/305

Section B: General Site Information

Site Name:
If site is a reoccupation of an
old DSDP/ODP Site, Please
include former Site#

50m from MOO69A

Latitude:Deg:

Longitude:

Deg:

Jurisdiction: common

30.1317

Distance to Land:(km)-42.1202

Coordinate System:
Priority of Site:

Area or Location: Mid Atlantic Ridge, Atlantis Massif

AMDH-02A

WGS 84
Primary:

Generated: 2019-10-11T00:26:09+00:00✓⃞

Alternate:⃞

Water Depth (m): 825

Section C: Operational Information
Sediments

Basement

3200

Proposed
Penetration (m):Total Sediment Thickness (m)3Total Penetration (m):General Lithologies:
Coring Plan:(Specify or check)serpentite, talc-tremolite chlorite schist,
metadiabase, metagabbro, breccia, fault rockloose foram sandPilot Hole 50m; hard rock re-entry system with ~15m casing; 2-bit Hole to 200m
APC

Wireline Logging
Plan:

203

XCB

RCB

Standard Measurements

Special Tools

✓
✓
✓
✓
✓
✓
✓

Magnetic Susceptibility

WL
Porosity
DensityGamma Ray
Resistivity
Sonic (∆t)
Formation Image (Res)

Borehole Temperature✓✓

Re-entry✓

Other
tools:

MTT tool, ETBS tool, WSTP tool,
potentially Kuster tool (exact choice oftools may be an operational choice)Formation Image(Acoustic)PCS

VSP (walkaway)
LWD

VSP (zero offset)
Formation Temperature& Pressure
Other Measurements:

Estimated Days:

Drilling/Coring:

5.1

Logging:

Observatory Plan:

Longterm Borehole Observation Plan/Re-entry Plan

Potential Hazards/
Weather:

Shallow Gas

Complicated Seabed
Condition

Hydrocarbon

0.5

Total On-site:

5.6

Hard rock re-entry system. Potential for observatory✓ Hydrothermal Activity

Preferred weather window

Soft SeabedLandslide and Turbidity
Current

December to May(avoiding Atlantic
hurricane season)

Shallow Water Flow

Currents

Gas Hydrate

Abnormal Pressure

Fracture Zone

Man-made Objects(e.g., sea-floor cables,
dump sites)

H2S✓ Fault
High Dip Angle✓ Diapir and Mud Volcano✓ High Temperature
Ice Conditions

CO2
Sensitive marine
habitat (e.g., reefs,

Lost City Hydrothermal Field is ~0.5 km away

vents)

Other:

Generated: 2019-10-11T00:26:09+00:00

Pieces of RD2 drill string left in MOO69A may not be visible. Hardrock seabed with rubble andsmall sediment ponds

IODP Site Forms

Proposal #:937 - Full 2

Form 2 - Site Survey Detail

Site #:

AMDH-02A

Date Form Submitted: 2019-10-10 17:10:16

Data TypeIn SSDB

1a High resolution seismic reflection (primary)no1b High resolution seismic seismic reflection (crossing)no2a Deep penetration seismic reflection (primary)yes

Line: Meg4 ,Position: CMP# 3480 closest, 190 m to east; ~RP# 2726 in
meg4_stack_2400_5280.segy

2b Deep penetration seismic reflection (crossing)yes

Line: Meg9
Position: CMP 2750, 375 m north

3 Seismic Velocity

yesHarding et al. 2016 & in prep- Meg4 & Meg9 waveform inversion (older
version Henig et al. 2012 Meg4 & 9 downward continued to seafloor
streamer tomography)

4 Seismic Gridyes

Meg4, Meg5, Meg6, Meg9, Meg10- Canales et al., 2004 (Meg8 outside
corner)5a Refraction (surface)yes

OBS refraction- Blackman and Collins 2010; Line 9a near site

5b Refraction (bottom)

no6 3.5 kHzno

7 Swath bathymetryyes

8a Side looking sonar (surface)no8b Side looking sonar (bottom)

yes

CD100 Tobi MARVEL2000 DSL120

9 Photography or video

yes

MARVEL 2000 Alvin and Argo images

10 Heat Flowno11a Magnetics

yes

Pariso et al., 1996; MARVEL2000 deep-tow

11b Gravity

yesBlackman et al., 2008

12 Sediment coresno13 Rock samplingyes

14a Water current datano14b Ice Conditions

no15 OBS microseismicity

no1 yr study, Collins et al. 201216 Navigation

yes

MCS, OBS refraction, DSL120, Alvin rock sample & dredge locations

17 Otherno

Generated: 2019-10-11T00:26:09+00:00

Details of available data and data that are still to be collected

CD100 EM12, MARVEL2000 SeaBeam2000, 100-m regional gridBlackman et al., 2008. EM120 20-50m grid Früh-Green et al., 2017.

CD100 Dredge, MARVEL2000 Alvin; Exp357 Holes M0069A; M0072A,B;
M0076A,BIODP Site Forms

Proposal #:937 - Full 2

Form 4 - Environmental Protection

Site #:

AMDH-02A

Date Form Submitted: 2019-10-10 17:10:16

Pollution & Safety Hazard

Comment

1. Summary of operations at site

RCB pilot Hole 50m; Hard rock re-entry system with ~17 m casing; RCB to 100mbsf; temperaturelog at end of drilling and logging, temperature, and fluid sampling at end of expedition

2. All hydrocarbon occurrences based on
previous DSDP/ODP/IODP drillingnone

3. All commercial drilling in this area that
produced or yielded significant
hydrocarbon showsnone

4. Indications of gas hydrates at thislocationnone

5. Are there reasons to expecthydrocarbon accumulations at this site?

none

6. What "special" precautions will betaken during drilling?

none

7. What abandonment procedures need
to be followed?

standard

8. Natural or manmade hazards which
may affect ship's operations

junk in Hole M0069A

9. Summary: What do you consider the
major risks in drilling at this site?

serpentinite fault zone so drilling conditions may be difficult

Generated: 2019-10-11T00:26:09+00:00

IODP Site Forms

Proposal #:Form 5 - Lithologies

937 - Full 2

reflectors,
Subbottom Key
depth (m) unconformities,
faults, etc

Age (My)

0 - 6.50Site #:

AMDH-02A

Assumedvelocity(km/s)

Lithology

Date Form Submitted: 2019-10-10 17:10:16

Paleo-environment

Avg. accum.
rate (m/My)

Comments

loose carbonate
sand in pockets.
rubble possible

Based on M0069A,
50 m away, but
sediment pockets
very variable

6.5 - 121

metadiabase

based on M0069A.
Good recovery in thissection, but may notoccur based onmoderately dipping
contact

12.5 13.2

1

sub-horizontal fault
zone and breccia

based on M0069A.
Similar fault zones
likely throughout
sectionheterogeneous
fault/shear zone
dominated byserpentinite

13-16.5 mbsf sectionin M0069A was
massive serpentinite
with good recovery

13.2 - 100

Generated: 2019-10-11T00:26:09+00:00

20m_march2018.grd
05

km/s

3000

2000

1000

ORB2

OBH16

depth (0-5 km)a-02 ed)DH
AM roject
(p

e9b

1

Depth (km)

Lin

orb

30.2333˚

−3000

966

986 961U1309D

ob
0

2

−2

30.1667˚

b3

1011

1016

2.0
3150

3320

CMP#

3490

3660

30.100˚

931−1000
00
0

or

936

−1

30.1333˚

1.5

941

1006

a

(mod. Canales
et al. 2004)

951 26h996
ob
AMDH-02A
946
6
1001
h1
ob

Line9

A

02

H-

D
AM

500 m

00

3000 RP#

2500

956

991

h2

0

Two-way Travel Time (sec)05

distance( -8 to 9 km)

D
AM

00

Meg4, uninterpreted
Reverse Time Migration

9D

30

U1

−2

MCS: meg9migrated.segy, meg9stack.segy,
meg9.cdp_nav_bat_twtt,meg4_stack_2400_5280.segy (correctnav), meg4migrated.segy (needs nav), meg4.cdp_nav_bt_twtt
Refraction: orb1n09.segy, obh16n9.segy, obh26n9.segy,
orb2n09.segy

le

Ho

ORB1

A

02
H-

Meg4 Stack, zoom

distance along MCS Line Meg4 (km)OBH26

30.2000˚

1.0

21

25-m contour interval, 100-m heavy

Blackman & Collins, GRL 2010

(mod.Harding et al., 2016)base
gabbroic
body?

Meg9

−42.0833˚−42.1˚−42.1167˚

Line9a5.25
km/s
contour

01
22

22

97

24

M0068

atlantis.grd

metersMeg4 Waveform Inversion
zoom section

1500
1000 m
20m contours

3305

Meg10

U1309D

01

3401M0076−42.1333˚−42.15˚

distance along Meg4 (km)Depth (km)-42.1167°

1505−42.1667˚

depth
(km)

97
25

AMDH−02A
M0072

1697

N

02A

AMDH-2A

05
27

01

30

28

3497
M0069

1601

HAMD

Meg9

3605

28

05

01

M0071

Depth (km)

1901

1805

30.1333˚Interpreted Reverse Time Migration

3701

25

22
97

31

33

km/s

S

1997

M0070

AMDH−03A

Meg4 Waveform Inversion(mod. Harding et al. 2016)

200 m

30.1333°

3797

97

05

01

Lost City
MCS Line
w/CMP#

34

Meg6

M0073

Exp 357

30.15˚

Meg4

IODP 937 Full-2, Site Figure AMDH-02A

09

E

32

W

2

orb

926
921

−42.1667˚ −42.1333˚ −42.1000˚

IODP Site Forms

937 - Full

Form 1 – General Site Information

2

Section A: Proposal Information

Proposal Title

Date Form Submitted

Accessing the Building Blocks of Life: Deepening Hole U1309D, Atlantis Massif, Mid-Atlantic Ridge

2019-10-10 17:10:16

Site-Specific Drill through detachment fault shear zone; igneous petrology, alteration, deformation fabrics, microbiology,
Objectives with organic geochemistry. potential for post-detachment volcanic rocks. Temperature profile, fluid sampling,
potential to provide re-entry system for legacy
Priority(Must include generalobjectives in proposal)

List Previous
Drilling in Area

IODP Exp 357; IODP Exp 304/305

Section B: General Site Information

Site Name:

Area or Location: Mid Atlantic Ridge, Atlantis Massif

AMDH-03A

If site is a reoccupation of an
old DSDP/ODP Site, Please
include former Site#

Latitude:Deg:

Longitude:

Deg:

Distance to Land:(km)-42.1455

Coordinate System:
Priority of Site:

Jurisdiction: common

30.1389

WGS 84
Primary:

Generated: 2019-10-11T00:26:09+00:00⃞

Alternate:✓⃞

Water Depth (m): 1275

Section C: Operational Information
Sediments

Basement

5200

Proposed
Penetration (m):Total Sediment Thickness (m)5Total Penetration (m):General Lithologies:
Coring Plan:(Specify or check)serpentite, talc-tremolite chlorite schist,
metadiabase, metagabbro, breccia, fault rockloose foram sand; carbonate cemented breccia

single bit to destruction, but if AMDH-01A fails completely, deeper Hole with re-entry. Sediment thickness is likely
maximum based on previous Holes (M0070; M0071, Site U1309)
APC

Wireline Logging
Plan:

205

XCB

RCB

Standard Measurements

Special Tools

✓
✓
✓
✓
✓
✓
✓

Magnetic Susceptibility

WL
Porosity
DensityGamma Ray
Resistivity
Sonic (∆t)
Formation Image (Res)

Borehole Temperature✓✓

Re-entry

Other
tools:

Formation Image(Acoustic)

PCS

MTT, ETBS for temperature. Kuster
and/or WSTP tool for fluid sampling(temperature probably too low to use
new SMA tool)

VSP (walkaway)
LWD

VSP (zero offset)
Formation Temperature& Pressure
Other Measurements:

Estimated Days:

Drilling/Coring:

Logging:4

1

Total On-site:

5

Observatory Plan:

Longterm Borehole Observation Plan/Re-entry Plan

Potential Hazards/
Weather:

Shallow Gas

Complicated Seabed
Condition

Hydrothermal Activity

Preferred weather window

Hydrocarbon

Soft SeabedLandslide and Turbidity
Current

December to May(avoiding Atlantic
hurricane season)

Shallow Water Flow

Currents

Gas Hydrate

Abnormal Pressure

Fracture Zone

Man-made Objects

Fault

H2S

High Dip Angle

depending on time, a re-entry system may be installed with potential for future instrumentation(e.g., sea-floor cables,
dump sites)

CO2
Sensitive marine
habitat (e.g., reefs,

vents)

Other:

Generated: 2019-10-11T00:26:09+00:00✓ Diapir and Mud Volcano✓ High Temperature
Ice Conditions

IODP Site Forms

Proposal #:937 - Full 2

Form 2 - Site Survey Detail

Site #:

AMDH-03A

Date Form Submitted: 2019-10-10 17:10:16

Data TypeIn SSDB

1a High resolution seismic reflection (primary)no1b High resolution seismic seismic reflection (crossing)no2a Deep penetration seismic reflection (primary)yes

Line: Meg9
Position: ~CMP 3125

2b Deep penetration seismic reflection (crossing)yes

Line: Meg6
Position: ~600m to east

3 Seismic Velocity

yesHarding et al. 2016 & in prep- Meg9 waveform inversion (older version
Henig et al. 2012 Meg9 downward continued to seafloor streamer
tomography)

4 Seismic Gridyes

Meg4, Meg5, Meg6, Meg9, Meg10- Canales et al., 2004 (Meg8 outside
corner)5a Refraction (surface)yes

OBS refraction- Blackman and Collins 2010; Line 9b closest to site

5b Refraction (bottom)

no6 3.5 kHzno

7 Swath bathymetryyes

8a Side looking sonar (surface)no8b Side looking sonar (bottom)

yes

CD100 Tobi MARVEL2000 DSL120

9 Photography or video

yes

MARVEL 2000 Alvin and Argo images

10 Heat Flowno11a Magnetics

yes

Pariso et al., 1996; MARVEL2000 deep-tow

11b Gravity

yesBlackman et al 2008

12 Sediment coresno13 Rock samplingyes

14a Water current datano14b Ice Conditions

no15 OBS microseismicity

no1 yr study, Collins et al. 201216 Navigation

yes

MCS, OBS refraction, DSL120, Alvin rock sample & dredge locations

17 Otherno

Generated: 2019-10-11T00:26:09+00:00

Details of available data and data that are still to be collected

CD100 EM12, MARVEL2000 SeaBeam2000, 100-m regional gridBlackman et al., 2008. EM120 20-50m grid Früh-Green et al., 2017.

CD100 Dredge, MARVEL2000 Alvin; Exp 357 cores, M0070A-c andM0071A to C most relevant

IODP Site Forms

Proposal #:937 - Full 2

Pollution & Safety Hazard
1. Summary of operations at site
2. All hydrocarbon occurrences based on
previous DSDP/ODP/IODP drilling
3. All commercial drilling in this area that
produced or yielded significant
hydrocarbon shows
4. Indications of gas hydrates at thislocation
5. Are there reasons to expecthydrocarbon accumulations at this site?
6. What "special" precautions will betaken during drilling?
7. What abandonment procedures need
to be followed?
8. Natural or manmade hazards which
may affect ship's operations
9. Summary: What do you consider the
major risks in drilling at this site?

Generated: 2019-10-11T00:26:09+00:00

Form 4 - Environmental Protection

Site #:

Comment

AMDH-03A

Date Form Submitted: 2019-10-10 17:10:16

IODP Site Forms

Proposal #:Form 5 - Lithologies

937 - Full 2

reflectors,
Subbottom Key
depth (m) unconformities,
faults, etc

Age (My)N/A

Generated: 2019-10-11T00:26:09+00:00

Site #:

AMDH-03A

Assumedvelocity(km/s)

Lithology

Date Form Submitted: 2019-10-10 17:10:16

Paleo-environment

Avg. accum.
rate (m/My)

Comments

distance (km)

S

TWTT

km/s

-8

5
4
3
2

22
97

05

05

01

21

22

22

97

25

24

01

97

27

28

05

01

97

25

e9b

1

Line 9b
central(solidarrow)(dashedarrow,
profileat left)

−3000

2

4

5

7

ORB1

2

N
or

4

6

8

6

h2

ob

946

6

h1

ob

U1309D
941
936

1011

b3 AMDH-03A

1016

4
2
0
distance (km)

951

996

1006

Refraction Line 9b

oj)
A (pr

3

-2

956

991

h2

1001

30.1˚

-4

ob

8

velocity (km/s)

3

H-0
AMD

6

1

orb

966

986 961

30.2˚

2

5

meters−1000

Line 9acentral

9b
south

OBH22

ORB3

1

depth (km)6

MCS: meg9migrated.segy, meg9stack.segy,
meg9.cdp_nav_bat_twtt
Refraction: orb3n09.segy, obh22n9.segy, orb1n09.segy
Velocity models (waveform inversion): Meg9velModel.txt

9a
south

0

7

CMP #

0

same color and VE scale as Meg 9 zoom but
slightly different than both in Meg 4 velocity
zoom on AMDH-02A Site Figure

AMDH-03A

−2000

0

-10

−3000

E

Meg9

2.0

−4000

Lin

AMDH-02A

1.0

2.0

200 m

W

−5000

00
0

2

Meg 4 FWI near
Meg9 crossing,velocity zoom

00

A

3
-0

DH
AM

3

Depth (km)(data Canales et al., 2004)−42.0833˚−42.1˚−42.1167˚

000−2

Two-Way Travel Time (sec)

1.0

Meg 9 Stack−42.1333˚−42.15˚

25-m contour interval, 100-m heavy

-4

A
02
H- j)
D
o
AM (pr

Meg9

M0068

3305

subseafloor depth (km)

Meg4

Meg6
-6

-8

3401M0076−1

Depth (km)

2

1697

1505

−42.1667˚

2.0

3497
M0069

AMDH−02A
M0072

1601

5
4

3

3605

a

A

-03

DH
AM

1901

Line9

Meg 9 FWI
velocity zoom

3701

−2

1.0

1997

28

33
05

M0071

Distance along Meg9 (km)AMDH-02A
km/s(proj)Exp 357
Lost City
MCS Line
w/CMP#

1805

30.1333˚

M0073

3797

M0070

AMDH−03A

Meg4

2.0

Meg4

Meg6

30.15˚
34
01

D
AM

30
05

1.0

km/s

31
01

AMDH-02A(proj)

A

03
H-

Meg6

Depth (km)(Harding, in prep)

IODP 937 Full-2, Site Figure AMDH-03A

E

32
09

Meg 9 Full Waveform Inversion Velocity

W931−1000

2

orb

926

921

−42.1667˚ −42.1333˚ −42.1000˚