The impact of African aridity on the isotopic signature of Atlantic deep waters across the Middle Pleistocene Transition |
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| Authors: | Bruno Malaizé Elsa Jullien Amandine Tisserand Charlotte Skonieczny E Francis Grousset Frédérique Eynaud Catherine Kissel Jérôme Bonnin Svenja Karstens Philippe Martinez Aloys Bory Vivianne Bout-Roumazeilles Thibaut Caley Xavier Crosta Karine Charlier Linda Rossignol José-Abel Flores Ralph Schneider |
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| Institution: | 1. UMR CNRS 5805 EPOC, Université Bordeaux I, 33405 Talence, France;2. Department of Earth sciences, University of Bergen, Realfagb, Allègt. 41, Bergen, Bjerknes Centre for Climate Research, BCCR, Allègaten 55, 5007 Bergen, Norway;3. FRE CNRS 3298 GEOSYSTEMES, Université de Lille I, 59655 Villeneuve d''Ascq, France;4. Laboratoire des Sciences du Climat et de l''Environnement/IPSL, CEA/CNRS/UVSQ, Avenue de la Terrasse, Bat 12, 91198 Gif-sur-Yvette Cedex, France;5. Departamento de Geología, Universidad de Salamanca, 37008, Salamanca, Spain;6. Institut fuer Geowissenschaften, Christian-Albrechts-Universitaet, 10/24118 Kiel, Germany |
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| Abstract: | A high resolution analysis of benthic foraminifera as well as of aeolian terrigenous proxies extracted from a 37 m-long marine core located off the Mauritanian margin spanning the last ~ 1.2 Ma, documents the possible link between major continental environmental changes with a shift in the isotopic signature of deep waters around 1.0–0.9 Ma, within the so-called Mid-Pleistocene Transition (MPT) time period. The increase in the oxygen isotopic composition of deep waters, as seen through the benthic foraminifera δ18O values, is consistent with the growth of larger ice sheets known to have occurred during this transition. Deep-water mass δ13C changes, also estimated from benthic foraminifera, show a strong depletion for the same time interval. This drastic change in δ13C values is concomitant with a worldwide 0.3‰ decrease observed in the major deep oceanic waters for the MPT time period. The phase relationship between aeolian terrigeneous signal increase and this δ13C decrease in our record, as well as in other paleorecords, supports the hypothesis of a global aridification amongst others processes to explain the deep-water masses isotopic signature changes during the MPT. In any case, the isotopic shifts imply major changes in the end-member δ18O and δ13C values of deep waters. |
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