M. Triantaphyllou.: Short note on small Gephyrocapsa species ... , p. 37 - 40.

Journal of Nannoplankton Research, 22, I, 2000.

SHORT NOTE ON THE OCCURRENCE OF SMALLGEPHYROCAPSA SPECIES AND BIREFRINGENT CERATOLITHSIN MESSINIAN DIATOMITES (GAVDOS ISLAND,SOUTHERN GREECE)Maria Triantaphyllou
Dept. of Geology, Section of Historical Geology & Palaeontology, University of Athens,
Panepistimiopolis 15784, Athens, Greece
Abstract: The occurrence of small Gephyrocapsa species, along with sporadic birefringent ceratoliths andAmaurolithus tricorniculatus, has been documented from Gavdos Messinian diatomites. This is the firsttime this assemblage has been observed in the Greek region.

futroduction
Gavdos Island forms the southemmost extension of the S
Aegean arc, and is located approximately 23 miles S of
Crete (Figure 1). The Neogene sediments covering most of
the surface area of the island are subdivided into two
lithostratigraphic formations, the Potamos and the Metochia(Anastasakisetal., 1995).

present study is an attempt to understand the biostratigraphic significance of the nannoflora.
Material and methods
Fifteen samples from the upper 12m of the diatomite
sequence of the Metochia C section were analysed (Figure2). The distribution of calcareous nannofossil taxa wasdetermined by LM, and additional detailed SEM analysis
was applied to several samples. Both observational
techniques were used in order to get the maximum amountof information from the studied material. Preparation ofsmear-slides for light microscopy, and of the samples for
the SEM analysis followed standard procedures (Bown &Young, 1998). Semiquantitative analysis (presence of thespecies in 40 fields of view under 1250x magnification) wasused to estimate the abundances of the discoasterid andrare ceratolithid forms.

0

N

t

Small Gephyrocapsa spp.
The genus Gephyrocapsa was once considered to be
restricted to the Quaternary. In the Mediterranean region,
Dermitzakis & Theodoridis (1978) and Muller (1978)
reported small Gephyrocapsa from the Lower Pliocene(NN13), whilst Pirini Radrizzani & Valleri (1977) andLohmann & Ellis (1981) described new species from theLower Pliocene, observing an increase in size towards
higher stratigraphic levels. Raffi & Rio (1979) observed
these below the last occurrence (LO) of Amaurolithus
delicatus, and Driever (1988) also reported several forms
from the Lower Pliocene.
Rio ( 1982) pointed out that small Gephyrocapsa in the
Mediterranean appear near the LO of Globorotalia
margaritae or the first occurrence (FO) of Pseudoemiliania
lacunosa, reaching a maximum size of 3.51JII1. The FO of
Gephyrocapsa has been established near the Lower/Upper
Pliocene boundary, whereas small Gephyrocapsa
specimens are usually common in the lower part ofNN16(Young, 1998), i.e. the Lower Pliocene. However, the precise
stratigraphic distribution of the genus still remains
uncertain, since Gephyrocapsa representatives have beenreported in Miocene sedirnents from the Pacific and Atlantic
Oceans (Pujos, 1987; Jiang & Gartner, 1984). In the
Mediterranean, Bonci & Pirini Radrizzani (1992) have noted
the presence of small Gephyrocapsa in the Upper Miocene

0

Figure 1: Location of the Metochia C section , Gavdos Island.

Thinly-bedded diatomites are located at the top of the
Metochia C section (Metochia Formation). Hilgen et a((1995) correlated these with the lithostratigraphic unit of
the Tripoli diatomites and have astronomically-dated thebase of the pre--evaporitic sequence at 6. 70Ma. Additionally,
Triantaphyllou et al. ( 1999) correlated the upper part of the
diatomite sequence, through nannofossil biostratigraphy,
with CN9b (of Okada & Bukry, 1980), with the upper part of
NN11 (ofMartini, 1971), and with the Calcidiscus leptoporus
Zone (of Theodoridis, 1984), giving it a Late Messinianage.
The present study records the occurrence of small
Gephyrocapsa spp., along with sporadic birefringent
ceratoliths and Amaurolithus tricorniculatus, from the
Gavdos Messinian diatomites. This assemblage is reported
for the first time from the Greek region, and the aim of the37

Journal of Nannoplankton Research, 22, 1, 2000.

LITHOLOGY

M. Triantaphyllou.: Short note on small Gephyrocapsa species ... , p.37 - 40.

SAMPLE

GDlO

LEGEND

GD9- - unconformity

GD8
GD7

diatomite
D clayey
diatomite

GD6
GDS
GD4
GD3
GD2
GDl

FO of C. acutus was reported to have been found 6m above
the base of the Zanclean at Capo Rosselo by Cita & Gartner(1973). However, Flores (1986) reported C. rugosustogether
with C. cristatus as the first ceratoliths to appear in the
Pliocene of SW Spain.
Mazzei et al. (1979) reported the FO of C. acutus at
DSDP Site 397 (NE Atlantic, NW African margin) at between
5.23Maand5.94Ma, andMi.iller inRogl etal. (1991) reported
the sporadic presence of C. acutus in the Upper Messinianof the Mediterranean. Raffi & Rio (1979) also reported,horseshoe-shaped' coccoliths which, being strongly
birefringent, could belong to the genus Ceratolithus.
Additionally, Mazzei in Benson & Rakic El Bied (1996)
reported the presence of C. acutus well into the Messinian,in the Moroccan section, Bou Regreg, placing its FO near
the base of Chron Gilbert.
In the present material, although extremely rare,birefringent ceratoliths -are definitely present (Plate 1,
Figures 5-8). It must be noted that they do not resemble C.
acutus but they may represent morphovariants of C.
rugosus. Rio et al. (1990a) considered that the FO of C.
rugosus in the Mediterranean appeared to be a migration
event, strongly diachronous with respect to the openocean sections.
The rest of the nannoflora observed in the Gavdos
diatomaceous sediments is particularly characterised by
the presence of Amaurolithus delicatus, A. primus, A.
amplificus, A. tricomiculatus, Discoaster quinqueramus,
D. pentaradiatus and D. berggrenii (Figure 3; Plate 1, Figs
1-4, 9-12). A. tricomiculatus is often recorded as appearing
in CN9b (e.g. Berggren et al., 1995), although Rio et al.
( 1990b) have observed its later appearance, within CN1 Oaf
CNlOb. The contemporaneous presence of A. tricorniculatus, D. quinqueramus, D. berggrenii and birefringent
ceratoliths in the Gavdos pre-evaporitic diatomites enables
us to conclude that the first representatives of thebirefringent ceratoliths were already present in the Late
Messinian.

•m

till
- diatomaceous mar!
limestone~ marly limestonelm

Figure 2: Lithostratigraphic column of the upper diatomaceous
sediments, Metochia C section.

diatomaceous levels of the Capella Montei section(Alessandria, Italy).
The presence of small Gephyrocapsa specimens in
Mediterranean Miocene sediments is supported once morethrough the present study. In particular, while investigating
this material with the SEM, the presence of small, butcharacteristic, gephyrocapsid forms (Plate 1, Figure 13)
was detected, which leaves no doubt about the presenceof the genus Gephyrocapsa in the Messinian pre-evaporitic
diatomites of Gavdos. The example shown in Plate 1
possesses an overall length of -3.8f.llll, whereas the central
opening measures l.5f.llll on the proximal side, a fact thatmakes the observation of a bridge extremely difficult bymeans of light microscopy, due to the resolution limit of
theLM.

Discussion and conclusions
The occurrence of small Gephyrocapsa specimens in
Gavdos Messinian diatomites contributes to the limited
knowledge about the precise stratigraphic and geographic
distribution of these early representatives of the genus in
the SE Mediterranean region, and offers palaeoecologicalimplications suggesting the possibility of a sudden arrivalof cooler surface-waters in the diatomaceous depositional
environment, since small Gephyrocapsa assemblages imply
intensified upwelling conditions (Gartner, 1988).
The presence of birefringent ceratoliths in the Late
Messinian supports earlier observations of diachroneity,
even within the Mediterranean region.
Both topics require further detailed investigation inorder to provide an accurate time-framework for these
events.

Birefringent ceratoliths
The earliest birefringent ceratoliths are represented by
Ceratolithus acutus and C. rugosus. The FO of C. acutus
was used by Bukry (1975) for the definition of the C. acutus
Subzone, corresponding to the upper part of NN12. The

Acknowledgements
The SEM analyses included in this paper were partially
funded by Research Project #70/4/3385 of the Universityof Athens. The author is very grateful to Prof. Dr. Herbert
Stradner and Dr. R. Surenian for their valuable help in SEM

38

M. Triantaphyllou.: Short note on small Gephyrocapsa species ... , p. 37 - 40.

Dermitzakis, M .D. & Theodoridis , S.A. 1978 . Planktonic
foraminifera and calcareous nannoplankton from the Plioceneof Koufonisi Islands (East Crete, Greece) . Ann. Geol. pays
Hell., 29: 630-643 .
Driever, B.W.M. 1988. Calcareous nannofossil biostratigraphy
and paleoenvironmental interpretation of the Mediterranean
Pliocene. Utrecht Micropal. Bull., 36: 245pp.
Flores, J.-A. 1986. Estudio sistematico de Ios Asterolitos dealgunas series del sector NO de la Cuenca del Guadalquivir(SO de Espaiia) y sondeos oceanicos DSDP proximos. I.
Studia Geol. Salmaticensia, 23: 219-263.
Grutner, S. 1988. Paleoceanography of the Mid-Pleistocene. Mar.
Micropal. , 13: 23-46.
Hilgen, F.J., Krijgsman, W. , Langereis, C.G., Lourens, L.J.,
Santarelli, A. & Zachariasse, W.J. 1995. Extending theastronomical (polarity) time scale into the Miocene. Earthand Planetary Science Letters, 136: 495-510.
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calcareous nannofossil biostratigraphy of the Walvis Ridge.
IRDSDP, 74: 561-595.
Lohmann, W.H. & Ellis, C.H. 1981. A new species and fossil
occurrences of calcareous nannoplankton in the eastern
Mediterranean. J. Paleontol., 55(2): 389-394.
Mrutini, E. 1971. Standard Tertiary and Quaternary calcareous
nannoplankton zonation. Proc. II Plankt. Conf, Roma 1970,
2: 739-785.
Mazzei, R., Raffi, I., Rio, D., Hamilton, N. & Cita, M.B. 1979.
Calibration oflate Neogene calcareous plankton datum planes
with the paleomagnetic record of Site 397 and correlation
with the Moroccan and Mediterranean sections. IRDSDP,
47: 375-389.
Muller, C. 1978. Neogene calcareous nannofossils from theMediterranean. Leg 42A of the Deep Sea Drilling Project.
IRDSDP, 42: 727-751.
Okada, H. & Bukry, D. 1980. Supplementary modification andintroduction of code numbers to the low-latitude coccolith
biostrati graphy zonation (Bukry, 1973; 1975) . Mar.
Micropaleont., 5(3): 321-325.
Pirini Radrizzani, C. & Valleri, G. 1977. New data on calcareous
nannofossils from the Pbocene of the Tyrrhenian Basin, Site
132, DSDPLeg 13. Riv. ltal. Paleont. Strat. , 83(4): 897-924.
Pujos, A. 1987. Late Eocene to Pleistocene medium-sized andsmall-sized , Reticulofenestrids". Abh. Geol. B-A. , 39: 239-

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Journal of Nannoplankton Research, 22, 1, 2000.

c F
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Figure 3: Di stribution of the nann ofoss il s in the Gavdos
diatomaceous sediments. A = abundant, C = common, R = rare, F =few.

studies at the Geological Survey of Austria (Vienna), andto Dr. P. Bown for kindly reviewing the manuscript. Thanks
are also expressed to colleague N. Tsaparas for providing
the study material.

277.

Raffi, I. & Rio, D. 1979. Calcareous nannofossil biostratigraphyof DSDP Site 132-Leg 13 (Tyrrhenian Sea-Western
Mediterranean). Riv. !tal. Paleont. Strat., 85: 127-172.
Rio, D. 1982. The fossil distribution of the coccolithophore genus
Gephyrocapsa Kamptner and related Plio-Pleistocene
chronostratigraphic problems. IRDSDP, 68: 325-343.
Rio, D., Fornaciari, E. & Raffi, I. 1990b. Late Oligocene throughearly Pleistocene calcareous nannofossils from the westernequatorial Indian Ocean (Leg 115). Proc. ODP, Sci. Res., ll5:
175-235.
Rio, D., Raffi, I. & Villa, G. 1990a. Pliocene-Pleistocenecalcareous
nannofossil distribution patterns in the Western
Mediterranean. Proc. ODP, Sci. Res., 107: 513-533.
Rogl, F. , Bernor, R .L. , Dermitzakis, M.D ., Muller, C. &Stancheva, M. 1991. On the Pontian correlation in the Aegean(Aegina island). Newsl. Strat., 24: 137-158.
Theodoridis, S. 1984. Calcareous nannofossil biozonation of the
Miocene and revision of the He1icoliths and Discoasters.
Utrecht Micropaleont. Bull. , 32: 372pp.
Triantaphyllou , M.V. , Tsaparas , N ., Stamataki s, M . &Dermitzaki s, M .D . 1999. Calcareous nannofossil
biostratigraphy and petrological analysis of the pre-evaporitic
diatomaceous sediments from Gavdos island, southern
Greece. N. Jb. Geol. Paliiont. , Mh ., 3: 161-178.
Young, J.R. 1998. Neogene. In: P.R. Bown (Ed.). Calcareous
Nannofossil Biostratigraphy . British Micropalaeonto-

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Stratigraphic framework of the Gavdos island Neogene
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Benson, R.H. & Rakic El Bied, K. 1996. The Bou Regreg Section,
Morocco: Proposed global boundary stratotype section andpoint of the Pliocene. Edit. Serv. Geol. Maroc, 383: 51-143.
Berggren, W.A., Kent, D.V., Swisher, C. C. & Aubry, M.-P. 1995.
A revised Cenozoic geochronology and chronostratigraphy.
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correlation: Framework for a historical geology. SEPM
Special Publication, 54: 129-212.
Bonci, M.C. & Pirini Radrizzani, C. 1992. Presence of small
Gephyrocapsa in Late Miocene diatomaceous levels (S. Agata
Fossili Formation, Serravalle Scrivia, Alessandria, Italy).
Mem. Sci. Geol. Padova, 43: 351-355.
Bown, P.R. & Young, J.R. 1998. Techniques. In : P.R. Bown
(Ed.). Calcareous Nannofossil Biostratigraphy. British
Micropalaeontological Society/Kluwer Academic Publishers:
16-28.
Bukry, D. 1975. Coccolith and silicoflagellate stratigraphy,
northwestern Pacific Ocean, DSDP Leg 32. IRDSDP, 32:
677-701.
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JogicalSociety!Kluwer Academic Publishers: 225-265.

39

M. Triamapllyllot.L: Short note on small Geplryrocapso peci ... , p. 37 - 40.

PLATE 1
Full taxon mi reference: can be~ uod in Pefi h- iel en 19 5

Fig.l: A. amplificu
SampleGD6

Fig.2: A. primu
Sample GD6

Fig.3: A. tricorniculatus
Sample GD6

Fig.4: A. delicatus
SampleGD6

Figs 7, 8: Ceratolithu sp.
Sample GD6

Figs S, 6: Ceratolithus p.
SampleGD6

Figs 9, 10: D. quinqueramu
SampleGD6r B wn 199

Fig.ll: D. berggrenii
Sample GD 1

Fig.13: Small Gephyrocapsa sp.
SampleGD540

Fig.12: D. pentaradiatu
Sample GD6