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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
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Medientyp |
Artikel
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Sprache |
Englisch
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 17 (2015) |
Datensatznummer |
250105135
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Publikation (Nr.) |
EGU/EGU2015-4585.pdf |
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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. |
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