MÉNOT, Guillemette; PIVOT, Sébastien; BOULOUBASSI, Ioanna; DAVTIAN, Nina; HENNEKAM, Rick; BOSCH, Delphine; DUCASSOU, Emmanuelle; BARD, Edouard; MIGEON, Sebastien; REVEL, Marie

doi:10.1016/j.quascirev.2019.106071

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MÉNOT, Guillemette
Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [LGL-TPE]

PIVOT, Sébastien
Centre Européen de Recherche et d'Enseignement des Géosciences de l'Environnement [CEREGE]

BOULOUBASSI, Ioanna
Cycles biogéochimiques marins : processus et perturbations [LOCEAN-CYBIOM]

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Quaternary Science Reviews. 2020-01, vol. 228, p. 106071

Résumé en anglais

Large fluvial systems, such as the Nile River, allow a basin-scale integrated view of climatological and environmental changes. In this study, we reconstructed the Nile discharge history for the last 20 ka using molecular ratios of glycerol dialkyl glycerol tetraethers (GDGTs) and neodymium (Nd) radiogenic isotopes. By characterizing both the organic and inorganic fractions, we assessed the relevance of the GDGT-based proxies in deltaic environments as tracers of terrigenous origin. A large increase in Nile discharge is documented from 14.8 to 8.4 ka BP reflecting enhanced physical erosion and transport processes from the Ethiopian Traps. We confirmed the primary control of insolation on precipitation on North East Africa through the last 20 ka. The centennial time resolution reached on the sedimentary sequence revealed a step-wise onset and termination of the African Humid Period (AHP) starting at 14.8 ka and ending at 8.4 ka BP, respectively. Our centennial-millennial records allowed furthermore pinpointing the abrupt periods of arid conditions corresponding to the Younger Dryas. These data illustrate the linkage between low and high latitude hydrological variability.< Réduire

Mots clés en anglais

Nile river

GDGT-indices

African Humid Period

Clastic εNd