 |
| Titel |
Late Neogene marine osmium isotopic records of the Mediterranean and Atlantic sediments |
| VerfasserIn |
Junichiro Kuroda, Francisco J. Jiménez-Espejo, Tatsuo Nozaki, Rocco Gennari, Stefano Lugli, Vinicio Manzi, Marco Roveri, Rachel Flecker, Francisco J. Sierro, Toshihiro Yoshimura, Katsuhiko Suzuki, Naohiko Ohkouchi |
| Konferenz |
EGU General Assembly 2017
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250144341
|
| Publikation (Nr.) |
 EGU/EGU2017-8152.pdf |
|
|
|
|
|
| Zusammenfassung |
| The Mediterranean Sea experienced a salinity crisis at Messinian, the end of Miocene (5.97 to
5.33 Ma) that resulted in the precipitation of thick evaporites (i.e., Mediterranean
salt giant) in deep and marginal basins [1]. We report osmium isotopic records
(187Os/188Os) of sediments from DSDP and ODP sites in the Mediterranean Sea: the
Balearic Sea (Site 372), the Tyrrhenian Sea (Site 654), the Ionian Basin (Site 374) and
the Florence Rise (Sites 375-376), as well as the Gulf of Cadiz, North Atlantic
(IODP Site U1387) [2]. Pliocene-Pleistocene sediments from all sites show isotopic
values close to that of the coeval ocean water, indicating that the Mediterranean was
connected to the North Atlantic. Messinian evaporitic sediments deposited during the
salinity crisis, however, have values significantly lower than the coeval ocean water
value. This offset is attributed to a limited inflow from the North Atlantic during the
salinity crisis. The unradiogenic osmium is likely to be supplied by weathering of
ultramafic rocks (ophiolites) cropping out in the Mediterranean drainage area. A box
model shows that the Atlantic-Mediterranean exchange rate dropped to about one
twentieth. Osmium isotopic ratios of the pre-evaporite sediments in the western
Mediterranean are nearly identical to that of the coeval ocean water. In contrast, equivalent
sediments from the Florence Rise have significantly lower isotopic values. This offset
could be attributed either to limited water exchange between eastern and western
Mediterranean, or to a local effect such as exhumation of the Troodos ophiolite in
Cyprus.
[1] Roveri et al. (2014) Marine Geology 352, 25–58.
[2] Kuroda et al. (2016) Paleoceanography 31, 148-166. |
|
|
|
|
|
|