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

Type Article
Date 2021-07
Language English
Author(s) Bastian Luc1, 2, Mologni CarloORCID1, 3, Vigier Nathalie2, Bayon Germain4, Lamb Henry5, 6, Bosch Delphine7, Kerros Marie-Emmanuelle2, Colin Christophe8, Revel Marie1
Affiliation(s) 1 : Université de la Cote d’Azur, CNRS, OCA, IRD, Geoazur, 250 rue Albert Einstein, 06500, Valbonne, France
2 : Laboratoire d’Océanographie de Villefranche sur Mer (LOV, IMEV), CNRS, Sorbonne Université, 181 chemin du Lazaret, 06320, Villefranche sur Mer, France
3 : Université Côte d’Azur, Centre National de la Recherche Scientifique (CNRS), Cultures et Environnements. Préhistoire, Antiquité, Moyen Age (CEPAM), UMR 7264, 24 av. des Diables Bleus, 06300, Nice, France
4 : IFREMER, Unité de Recherche Géosciences Marines, 29280, Plouzané, France
5 : Department of Geography and Earth Sciences, Aberystwyth University, Aberystwyth, SY23 3DB, UK
6 : Botany Department, School of Natural Sciences, Trinity College, Dublin 2, Ireland
7 : Géosciences Montpellier, UMR-CNRS 5243, Université de Montpellier, 34095, Montpellier, France
8 : Laboratoire GEOsciences Paris-Sud (GEOPS), UMR 8148, CNRS-Université de Paris-Sud, Université Paris-Saclay, Bâtiment 504, 91405, Orsay Cedex, France
Source Quaternary Science Reviews (0277-3791) (Elsevier BV), 2021-07 , Vol. 264 , P. 107012 (19p.)
DOI 10.1016/j.quascirev.2021.107012
WOS© Times Cited 4
Keyword(s) Chemical weathering, 110,000 ka BP, Lake Tana, Nile deep sea fan, Source-tosink approach, Nd isotope, Li isotope
Abstract

We have investigated provenance and weathering proxies of the clay-size sediment exported from the Nile River basin over the last 110,000 years. Using neodymium isotope composition of sediments from both the Nile Deep Sea-Fan and Lake Tana, we show that the Nile River branches draining the Ethiopian Highlands have remained the main contributors of clays to the Nile delta during the Late Quaternary. We demonstrate that fluctuations of clay-size particle contribution to the Nile Delta are mainly driven by orbital precession cycle, which controls summer insolation and consequently the African monsoon intensity changes. Our results indicate that - over the last 110,000 years – the proportion of clays coming from Ethiopian Traps fluctuates accordingly to the intensity of the last 5 precession cycles (MIS 5 to MIS 1). However, there is a threshold effect in the transport efficiency during the lowest insolation minima (arid periods), in particular during the MIS3. Several arid events corresponding to the Heinrich Stadial periods are associated with small or negligible clay source changes while chemical weathering proxies, such as δ7Li, Mg/Ti and K/Ti, vary significantly. This suggests a straightforward control of weathering by hydro-climate changes over centennial to millennial timescales. Our data also suggests a significant but more progressive influence of the temperature decrease between 110kyr and 20kyr. Taken altogether, the observed tight coupling between past climate variations and silicate weathering proxies leads us to conclude that precipitation changes in northeast Africa can impact soil development over a few hundred years only, while the influence of temperature appears more gradual.

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Bastian Luc, Mologni Carlo, Vigier Nathalie, Bayon Germain, Lamb Henry, Bosch Delphine, Kerros Marie-Emmanuelle, Colin Christophe, Revel Marie (2021). Co-variations of climate and silicate weathering in the Nile Basin during the Late Pleistocene. Quaternary Science Reviews, 264, 107012 (19p.). Publisher's official version : https://doi.org/10.1016/j.quascirev.2021.107012 , Open Access version : https://archimer.ifremer.fr/doc/00700/81162/