Circulation changes in the eastern Mediterranean Sea over the past 23,000 years inferred from authigenic Nd isotopic ratios

• Published in: Paleoceanography and Paleoclimatology
• Main Authors: Cornuault, Marine, TACHIKAWA, Kazuyo, VIDAL, Laurence, Guihou, Abel, Siani, Giuseppe, Deschamps, Pierre, Bassinot, Franck, Revel, Marie
• Other Authors: Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA), Géosciences Paris Sud (GEOPS), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Paléocéanographie (PALEOCEAN), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Géoazur (GEOAZUR 7329), Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement (IRD France-Sud )-Centre National de la Recherche Scientifique (CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2018
• Subjects: [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry; North Atlantic
• Online Access: https://hal.archives-ouvertes.fr/hal-01713452; https://hal.archives-ouvertes.fr/hal-01713452/document; https://hal.archives-ouvertes.fr/hal-01713452/file/Cornuault18P2%20copy.pdf; https://doi.org/10.1002/2017PA003227

International audience The Eastern Mediterranean Sea (EMS) is a key region to study circulation change because of its own thermohaline circulation. In this study, we focused on intermediate/deep water circulation since the Last Glacial Maximum (LGM) including the sapropel S1 period. Two cores from the Levantine Sea and the Strait of Sicily, respectively, collected at 1,780 m and 771 m water depth, were studied using 143Nd/144Nd (εNd) of foraminiferal tests and leachates as well as benthic foraminiferal stable isotopes (δ13C, δ18O). This approach allowed the determination of variations in (1) the North Atlantic water contribution to the Mediterranean basin, (2) water exchanges at the Strait of Sicily, and (3) the influence of the Nile River over the last 23,000 years. During the LGM, high benthic foraminiferal δ13C values indicate well‐ventilated intermediate and deep waters in the EMS. The εNd values were more radiogenic than at present, reflecting a smaller contribution of unradiogenic North Atlantic waters to the EMS due to reduced exchange at the Strait of Sicily. The sluggish circulation in the EMS initiated during deglaciation was further enhanced by increased Nile River freshwater inputs between 15 ka BP and the S1 period. Partial dissolution of Nile River particles contributed to an increase in EMS εNd. The large εNd gradient between the EMS and the Western Mediterranean Sea observed during LGM and S1 suggests that each basin had a distinct circulation mode. Decreasing εNd values at the Strait of Sicily after S1 reflected improved water exchange between both basins, leading to the modern circulation pattern.