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| Titel |
The Messinian/Early Pliocene transition in Eastern Mediterranean: New palaeoenvironmental data from the Kalamaki section (Zakynthos Island, Greece) |
| VerfasserIn |
Hara Drinia, Assimina Antonarakou, Theodora Tsourou, Evi Tzortzaki, Amalia Filippidi, Konstantinos Nikolaou |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250043971
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| Zusammenfassung |
| The purpose of this study is to describe the Miocene-Pliocene microfaunal development, and
to discuss its palaeoenvironmental and palaeogeographical significance. The studied section
(Kalamaki section) is located in the eastern part of Zakynthos Island (western Greece).
Details on lithology and stratigraphy of the section are given in Dermitzakis (1978) and
Nikolaou (1986).
Planktonic species indicate that sediments span the interval which corresponds to MPL1
Zone (Zanclean, early Pliocene) which is in accordance with the biostratigraphic
configuration of Rouchy et al. (1992) and Pierre et al. (2006). The studied interval is
characterized by the Sphaeroidinellopsis Acme Zone and the presence of Globorotalia
margaritae.
The recognized succession of microfossil assemblages serves to interpret the evolution
of some palaeoenvironmental factors (waterdepth, salinity and oxygen content),
whereas the planktonic foraminiferal zonation allows an age assignment to the
events.
During the Late Messinian brackish conditions became dominant. The early Pliocene
is characterized by a sudden return to well oxygenated, open marine, outer shelf
conditions.
At the basal part of the record, the high abundance of the ‘shallow water component’ of the
benthic foraminiferal fauna indicates a well-vegetated environment with either normal marine
salinity or a tendency to hyposalinity (e.g. Murray, 2006). Open marine conditions are
indicated by the diversity of benthic and planktonic foraminifera. The abundance of
Lenticulina spp., Cibicidoides pseudoungerianus, Planulina ariminensis, Pullenia,
Gyroidina, and the virtual absence of Cibicidoides dutemplei and other typical
shelf-taxa, suggest an upper bathyal waterdepth of 300-400 m (cf. Pujos, 1976; Jorissen,
1988).
Partly, the abundance of Cibicidoides pseudoungerianus, Bulimina costata and Uvigerina
peregrina reflect fluctuations in oxygen content of the bottom waters. However, extreme
conditions were never reached during deposition.
The foraminiferal facies distribution in the studied part of the Kalamaki section
is in accordance with isotope oxygen data from basins in the central and eastern
Mediterranean basin which indicates the existence of a salinity gradient during this time
span.
Ostracod fauna is characterised by low diversity and abundance. It is consisting
mainly of Bythocypris and Cytherella species, which confirm the bathyal depositional
environment.
The study of the late Messinian-Early Pliocene sediments in Zakynthos island (Kalamaki
section) correlated with time equivalent sections in Crete (e.g. Drinia et al., 2007) and the
comparison with the offshore coeval deposits drilled in the ODP Leg 160 boreholes, illustrate
the environmental changes which occurred in the Eastern Mediterranean at the end of the
salinity crisis.
References
Dermitzakis, M.D., 1978. Stratigraphy and sedimentary history of the Miocene of Zakynthos
(Ionian Islands, Greece). Ann. Geol. Pays Hell., 29:47 186.
Drinia, H., Antonarakou, A., Kontakiotis, G., 2007. On the occurrence of Early Pliocene
marine deposits in the Ierapetra Basin, Eastern Crete, Greece. Bulletin of Geosciences, 83
(1), 63-78.
Jorissen, F.J., 1988. Benthic foraminifera from the Adriatic Sea: principles of phenotypic
variation. Utrecht Micropaleontological Bulletins, 37, 1-174.
Murray, J., 2006. Ecology and applications of Benthic foraminifera. Cambridge University
press, 426pp.
Nikolaou, K.A., 1986. Contribution to the knowledge of the Neogene , the geology and the
limits of the Ionian and Preapulian zones, in relation to the petroleum exploration ,
observations in Strofades , Zakynthos and Kefallinia islands. The doct. University of
Athens.
Pierre, C., Caruso, A., Blanc-Valleron, M., Rouchy, J. M., Orzsag-Sperber, F., 2006.
Reconstruction of the paleoenvironmental changes around the Miocene-Pliocene boundary
along a West-East transect across the Mediterranean. Sedimentary Geology 188-189,
319-340. The Messinian Salinity Crisis Revisited.
Pujos, M., 1976. Ecologie des foraminifères benthiques et des thé-camoebiens de la Gironde
et du plateau continental Sud-Gascogne: application á la connaissance du Quaternaire
terminal de la région Ouest-Gironde. Memoires de l’ Institut de Géologie du Bassin d’,
Aquitaine, 8, 1-274.
Rouchy, J.-M. & Saint Martin, J.-P., 1992. Late Miocene events in the Mediterranean as
recorded by carbonate-evaporite relations. Geology, 20: 629-632. |
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