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

QUATERNARY SCIENCE REVIEWS

卷:264

Article

Bastian, Luc^1,2  Mologni, Carlo^1,3  Vigier, Nathalie²  Bayon, Germain⁴  Lamb, Henry^5,6  Bosch, Delphine⁷  Kerros, Marie-Emmanuelle²  Colin, Christophe⁸  Revel, Marie¹ 

[1] Univ Cote dAzur, CNRS, OCA, IRD, 250 Rue Albert Einstein, F-06500 Valbonne, France

[2] Sorbonne Univ, Lab Oceanog Villefranche Mer LOV, CNRS, IMEV, 181 Chemin Lazaret, F-06320 Villefranche Sur Mer, France

[3] Univ Cote dAzur, Ctr Natl Rech Sci CNRS, UMR 7264, Cultures & Environm Prehist Antiqu Moyen Age CEPA, 24 Av Diables Bleus, F-06300 Nice, France

[4] IFREMER, Unite Rech Geosci Marines, F-29280 Plouzane, France

[5] Aberystwyth Univ, Dept Geog & Earth Sci, Aberystwyth SY23 3DB, Dyfed, Wales

[6] Trinity Coll Dublin, Sch Nat Sci, Dept Bot, Dublin 2, Ireland

[7] Univ Montpellier, Geosci Montpellier, CNRS, UMR 5243, F-34095 Montpellier, France

[8] Univ Paris Saclay, Lab GEOsci Paris Sud GEOPS, CNRS Univ Paris Sud, UMR 8148, Batiment 504, F-91405 Orsay, France

关键词: Chemical weathering;    110,000 ka BP;    Lake Tana;    Nile deep sea fan;    Source-tosink approach;    Nd isotope;    Li isotope;   

DOI  :  10.1016/j.quascirev.2021.107012

来源: Elsevier

【 摘 要 】

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 delta Li-7, 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. (C) 2021 Elsevier Ltd. All rights reserved.

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