Hydrological conditions over the western Mediterranean basin during the deposition of the cold Sapropel 6 (ca. 175 kyr BP) |
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Authors: | Edouard Bard Gilles Delaygue Frauke Rostek Fabrizio AntonioliSergio Silenzi Daniel P Schrag |
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Institution: | a CEREGE, UMR 6635 CNRS and Université Aix-Marseille III, Europole de l’Arbois, 13545 Aix-en-Provence Cedex 4, France b Laboratory for Geochemical Oceanography, Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, MA 02138, USA c LSCE, UMR 1572 CNRS and CEA, Orme des Merisiers, 91191 Gif-sur-Yvette Cedex, France d ENEA National Agency for New Technologies, Energy and Environment, via Anguillarese 301, 00060 Roma, Italy e ICRAM Central Institute for Marine Research, via Casalotti 300, 00166 Roma, Italy |
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Abstract: | A new oxygen isotope record is reported from a stalagmite collected in the Argentarola Cave located on the Tyrrhenian coast of Italy. As shown from observations and numerical modeling of δ18O in modern precipitation, the recorded δ18O variability for this zone is dominated by the amount of precipitation (so-called ‘amount effect’). The δ18O profile measured in the stalagmite is characterized by a prominent negative excursion (ca. 2-3‰) between 180 and 170 kyr BP. This paleoclimatic feature is interpreted as being due to a relatively wet period which occurred during the penultimate glacial period, more precisely, during Marine Isotope Stage 6.5. This pluvial phase is shown to correspond chronologically to the deposition of the sapropel event 6 (S6). Although this particular sapropel event occurred during a cold phase, the δ18O excursion is similar to those corresponding to other sapropels (S4, S3 and S2). The evidence for humid conditions during S6 in the western Mediterranean basin agrees with previous studies based on deep-sea sediment cores. Taken collectively, the data suggest that during sapropel events dilution of ocean surface waters was not restricted to the output of the river Nile but was rather widespread over the entire Mediterranean Sea due to increased rainfall. |
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Keywords: | paleoclimatology speleothems sapropels modeling of oxygen isotopes Mediterranean Sea |
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