Changes in the intermediate water masses of the Mediterranean Sea during the last climatic cycle-new constraints from neodymium isotopes in foraminifera

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Date
2021-02-15
Authors
Colin, Christophe
Duhamel, Maxence
Siani, Giuseppe
Dubois-Dauphin, Quentin
Ducassou, Emmanuelle
Liu, Zhifei
Wu, Jiawang
Revel, Marie
Dapoigny, Arnaud
Douville, Eric
Taviani, Marco
Montagna, Paolo
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10.1029/2020PA004153
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Central Mediterranean Sea
foraminifera
last climatic cycle
Neodymium isotopic composition
paleo-hydrology
sapropels
Abstract
Variations in Mediterranean thermohaline circulation of the Quaternary are still not well constrained whereas they have been considered to have an influence on the Atlantic Meridional Overturning Circulation and on the oxygenation of waters in the deep basins of the Mediterranean Sea. εNd analyses have been carried out on planktonic foraminifera of cores collected in the central Mediterranean Sea to constrain water mass exchange between the Eastern and Western Mediterranean Sea (EMS and WMS) during the last climatic cycle. εNd records from the WMS and EMS display similar higher values during warm substages of interglacial Marine Isotopic Stage (MIS) 1 and 5. This suggests an efficient connection between the two Mediterranean sub-basins and the transfer of radiogenic waters to the Tyrrhenian Sea via the Levantine Intermediate Water (LIW). Conversely, during glacial MIS, εNd of the intermediate depth of the Tyrrhenian Sea are less radiogenic than the EMS, implying limited hydrological connection between sub-basins during low sea-level stands. Superimposed on these glacial-interglacial variations, increased εNd occurred during Heinrich Stadial events. This suggests a reduction in the formation of unradiogenic WIW in the Gulf of Lions due to the input of relatively fresh surface Atlantic water to the WMS and/or the inflow of radiogenic glacial LIW and upper EMDW to the Tyrrhenian Sea as a result of an active EMS convection related to saltier and colder conditions. Such potential millennial-scale pulses of LIW intrusion into the Tyrrhenian Sea may have led to an enhanced Mediterranean Outflow Water intensity in the Gibraltar Strait.
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Author Posting. © American Geophysical Union, 2021. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography and Paleoclimatology, 36(4), (2021): e2020PA004153, https://doi.org/10.1029/2020PA004153.
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Colin, C., Duhamel, M., Siani, G., Dubois-Dauphin, Q., Ducassou, E., Liu, Z., Wu, J., Revel, M., Dapoigny, A., Douville, E., Taviani, M., & Montagna, P. (2021). Changes in the intermediate water masses of the Mediterranean Sea during the last climatic cycle-new constraints from neodymium isotopes in foraminifera. Paleoceanography and Paleoclimatology, 36(4), e2020PA004153.
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