High Resolution Reconstruction of the Paleoenvironmental Changes Within the Mediterranean Sea Across the Miocene-Pliocene Boundary.
Abstract
A multidisciplinary study has been carried out with a high sampling resolution of the upper Messinian-lower Zanclean (biozone MPl1) sediments along a West-East Mediterranean transect from southern Spain (Vera/Almanzora), Balearic basin (ODP Site 975b), Sicily (Eraclea Minoa), Zakynthos (Kalamaki), Corfu (Aghios Stefanos), Crete (Aghios Vlasis), including previous data obtained in the Levantin Basin (Cyprus and ODP Sites 968 and 969). All the studied sections have been correlated using planktonic foraminiferal assemblages, sedimentological and stable isotope variations, and compared to the lithological cyclicity defined by Hilgen and Langereis (1988) in the Miocene Pliocene Boundary (MPB) stratotype of Eraclea Minoa, Sicily. The MPB displays strong variations of foraminiferal assemblages, CaCO3 content, oxygen and carbon stable isotopes of carbonates that can be correlated between the different studied sections. The uppermost Messinian deposits are barren of fossils or characterized by only reworked planktonic foraminifera, except for the sporadic presence of Ammonia beccarii tepida, ostracods and brackish mollusks typical of the "Lago-Mare" conditions. The bulk carbonate oxygen and carbon isotopic compositions usually exhibit large variations with dominant negative values indicating huge freshwater dilution. The lowermost part of the Pliocene (MPl1 biozone, cycle 1) shows a rapid and progressive increase of the isotopic values and the progressive recolonization by marine fauna; this indicates that at this time, the inflowing sea water was mixed with the brackish or fresh waters remaining in the basins and the planktonic foraminifers carried by sea water hardly survived in such stenohaline conditions. Stabilisation of normal marine conditions was established definitely at the base of cycle 2, i.e. one precession cycle after the re-establishment of connections between the Mediterranean and the Atlantic.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2005
- Bibcode:
- 2005AGUFMPP33A1556P
- Keywords:
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- 1041 Stable isotope geochemistry (0454;
- 4870);
- 3675 Sedimentary petrology;
- 4901 Abrupt/rapid climate change (1605);
- 4944 Micropaleontology (0459;
- 3030);
- 4999 General or miscellaneous