Co-variations of climate and silicate weathering in the Nile Basin during the Late Pleistocene

• Main Authors: Bastian, Luc, Revel, Marie, Menot, Guillemette, Bayon, Germain, Lamb, Henry, Pivot, S., Bard, Edouard, Vigier, Nathalie
• Other Authors: Laboratoire d'océanographie de Villefranche (LOV), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de la Mer de Villefranche (IMEV), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UniCA)-Université Côte d'Azur (UniCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD France-Sud ), École normale supérieure de Lyon (ENS de Lyon), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Collège de France - Chaire Evolution du climat et de l'océan, Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)
• Format: Conference Object
• Language: English
• Published: HAL CCSD 2019
• Subjects: [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Greenland; Greenland ice cores; North Atlantic
• Online Access: https://hal.science/hal-03550154

International audience During the Pleistocene, tropical Africa was the site of significant hydrologic changes related to variations in the intensity of the African monsoon. The socalled African Humid Period (AHP) has been known for some time, the AHP is being revisited today with the aid of innovative geochemical and organic tools such as lithium isotope and molecular biomarkers which allow variations in precipitation and their impact on the formation of soil to be quantified. Recent studies conducted at a high temporal resolution (10-1000 years) in lake and deltaic sedimentary records in Africa have suggested that gradual long-term monsoon intensity oscillations were often punctuated by millennial-scale episodes of hyperaridity. It is suspected that these rapid episodes had (and will have) an impact on human populations, but this remains to be conclusively demonstrated. Deltas are mainly fed by the influx of terrigenous material from flooded rivers and are extremely sensitive to changes in precipitation, vegetal cover, and their catchment areas. The spatio-temporal study of the Nile delta’s sediments has demonstrated that approximately 90% of the herrigenous material deposited in the Nile deep sea fan originates from erosion of the Ethiopian Highlands, especially during wet periods. The geochemical (Nd, Li isotopes andTi/Ca ratio) and molecular biomarker tracers have revealed the rapid development of centennial hyperarid episodes occurred contemporaneously with cold intervals recorded in Greenland ice cores (i.e. Greenland stadials or Heinrich Stadials recorded in North Atlantic sediment. The nature of the links between weathering and these hyperarid episodes are still under debate. In particular, the timescale over which chemical weathering may respond to hydroclimate change is yet to be determined at the continental scale. We will present a synthesis of works recently performed in the Nile Basin, which strongly suggests rapid and significant variations of silicate weathering, and a dominant role of ...