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Titel Miocene to Pliocene osmium isotopic records of Mediterranean sediments
VerfasserIn Junichiro Kuroda, Francisco J. Jiménez-Espejo, Tatsuo Nozaki, Rocco Gennari, Stefano Lugli, Vinicio Manzi, Marco Roveri, Rachel Flecker, Katsuhiko Suzuki, Toshihiro Yoshimura, Francisco Sierro, Naohiko Ohkouchi
Konferenz EGU General Assembly 2015
Medientyp Artikel
Sprache Englisch
Digitales Dokument PDF
Erschienen In: GRA - Volume 17 (2015)
Datensatznummer 250105135
Publikation (Nr.) Volltext-Dokument vorhandenEGU/EGU2015-4585.pdf
 
Zusammenfassung
In the late Miocene the Mediterranean Sea experienced a salinity crisis and thick sequences of evaporites precipitated across the basin. In this study we report Os isotopic records from drilled cores in the Mediterranean; the Balearic Sea, the Tyrrhenian Sea, the Ionian Basin and the Florence Rise. Pliocene sediments at all sites show 187Os/188Os values close to that of the coeval ocean water, indicating that the Mediterranean was connected to the North Atlantic. Evaporitic sediments deposited during the late Miocene however, have 187Os/188Os values lower than coeval ocean water values and samples from the eastern Mediterranean and Ionian basins are particularly low. Os isotopic ratios of the pre-evaporite sediments in the western Mediterranean are almost identical to that of the coeval ocean water. In contrast, equivalent sediments from the Florence Rise have significantly lower 187Os/188Os values. The offset of Mediterranean evaporite 187Os/188Os is attributed to limited exchange with the North Atlantic during the Messinian Salinity Crisis (MSC). The source of unradiogenic Os is likely to be weathering of ultramafic rocks (ophiolites) cropping out in the Mediterranean’s drainage basins. The offset in the Os ratio on the Florence Rise is attributed either to limited water exchange between eastern and western Mediterranean, or to local effects associated with exhumation of ophiolites around the eastern Mediterranean Sea.