Late Neogene marine osmium isotopic records of the Mediterranean and Atlantic sediments

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http://meetingorganizer.copernicus.org/EGU2017/EGU2017-8152.pdf
Author(s): Kuroda, Junichiro; Jimenez-Espejo, Francisco J.; Nozaki, Tatsuo; Gennari, Rocco; Lugli, Stefano; Manzi, Vinicio; Roveri, Marco; Flecker, Rachel; Sierro, Francisco J.; Yoshimura, Toshihiro; Suzuki, Katsuhiko; Ohkouchi, Naohiko
Author Affiliation(s): Primary:
University of Tokyo, Atmosphere and Ocean Research Institute, Kashiwa, Japan
Other:
Japan Agency for Marine-Earth Science and Technology, Japan
University of Parma, Italy
University of Turin, Italy
University of Modena and Reggio Emilia, Italy
University of Bristol, United Kingdom
University of Salamanca, Spain
Volume Title: European Geosciences Union general assembly 2017
Source: Geophysical Research Abstracts, Vol.19; European Geosciences Union general assembly 2017, Vienna, Austria, April 23-28, 2017. Publisher: Copernicus GmbH on behalf of the European Geosciences Union (EGU), Katlenburg-Lindau, Germany. ISSN: 1029-7006
Note: In English
Summary: 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. Roveri et al. (2014) Marine Geology 352, 25-58. Kuroda et al. (2016) Paleoceanography 31, 148-166. [Copyright Author(s) 2017. CC Attribution 3.0 License: https://creativecommons.org/licenses/by/3.0/legalcode]
Year of Publication: 2017
Research Program: DSDP Deep Sea Drilling Project
IODP Integrated Ocean Drilling Program
ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Atlantic Ocean; Balearic Basin; DSDP Site 372; DSDP Site 374; DSDP Site 375; DSDP Site 376; Deep Sea Drilling Project; East Mediterranean; Expedition 339; Florence Rise; Gulf of Cadiz; IODP Site U1387; Integrated Ocean Drilling Program; Ionian Sea; Leg 107; Leg 42A; Mediterranean Sea; North Atlantic; ODP Site 654; Ocean Drilling Program; Tyrrhenian Sea; West Mediterranean
Coordinates: N400152 N400154 E0044747 E0044747
N364819 N364820 W0074308 W0074308
N344544 N344545 E0304535 E0304534
Record ID: 2018041163
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from European Geosciences Union, Munich, Germany