Pedo-sedimentary constituents as paleoenvironmental proxies in the Sudano-Sahelian belt during the Late Quaternary (southwestern Chad Basin)

Détails

ID Serval
serval:BIB_45690399030A
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Institution
Titre
Pedo-sedimentary constituents as paleoenvironmental proxies in the Sudano-Sahelian belt during the Late Quaternary (southwestern Chad Basin)
Périodique
Quaternary Science Reviews
Auteur⸱e⸱s
Diaz Nathalie, Dietrich Fabienne, Sebag David, King Georgina E., Valla Pierre G., Durand Alain, Garcin Yannick, de Saulieu Geoffroy, Deschamps Pierre, Herman Frédéric, Verrecchia Eric P.
ISSN
0277-3791
Statut éditorial
Publié
Date de publication
07/2018
Peer-reviewed
Oui
Volume
191
Pages
348-362
Langue
anglais
Résumé
Climate and environmental changes since the Last Glacial Maximum in the tropical zone of West Africa are usually inferred from marine and continental records. In this study, the potential of carbonate pedo-sedimentary geosystems, i.e. Vertisol relics, to record paleoenvironmental changes in the southwestern part of Chad Basin are investigated. A multi-dating approach was applied on different pedogenic organo-mineral constituents. Optically stimulated luminescence (OSL) dating was performed on the soil K-rich feldspars and was combined with radiocarbon dating on both the inorganic (14Cinorg) and organic carbon (14Corg) soil fractions. Three main pedo-sedimentary processes were assessed over the last 20 ka BP: 1) the soil parent material deposition, from 18 ka to 12 ka BP (OSL), 2) the soil organic matter integration, from 11 cal ka to 8 cal ka BP (14Corg), and 3) the pedogenic carbonate nodule precipitation, from 7 cal ka to 5 cal ka BP (14Cinorg). These processes correlate well with the Chad Basin stratigraphy and West African records and are shown to be related to significant changes in the soil water balance responding to the evolution of continental hydrology during the Late Quaternary. The last phase affecting the Vertisol relics is the increase of erosion, which is hypothesized to be due to a decrease of the vegetation cover triggered by (i) the onset of drier conditions, possibly strengthened by (ii) anthropogenic pressure. Archaeological data from Far North Cameroon and northern Nigeria, as well as sedimentation times in Lake Tilla (northeastern Nigeria), were used to test these relationships. The increase of erosion is suggested to possibly occur between c. 3 cal ka and 1 cal ka BP. Finally, satellite images revealed similar geosystems all along the Sudano-Sahelian belt, and initial 14Cinorg ages of the samples collected in four sites gave similar ages to those reported in this study. Consequently, the carbonate pedo-sedimentary geosystems are valuable continental paleoenvironmental archives and soil water balance proxies of the semiarid tropics of West Africa.
Mots-clé
Archaeology, Archaeology, Global and Planetary Change, Geology, Ecology, Evolution, Behavior and Systematics
Web of science
Création de la notice
13/08/2018 17:39
Dernière modification de la notice
24/12/2022 6:44
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