Application of the authigenic 10Be/9Be dating method to continental sediments: Reconstruction of the Mio-Pleistocene sedimentary sequence in the early hominid fossiliferous areas of the northern Chad Basin

Anne-Elisabeth Lebatard; Didier L. Bourlès; Regis Braucher; Maurice Arnold; Philippe Duringer; Marc Jolivet; Abderamane Moussa; Pierre Deschamps; Claude Roquin; Julien Carcaillet; Mathieu Schuster; Fabrice Lihoreau; Andossa Likius; Hassan Taisso Mackaye; Patrick Vignaud; Michel Brunet

doi:10.1016/J.EPSL.2010.06.003

Journal articles

Application of the authigenic 10Be/9Be dating method to continental sediments: Reconstruction of the Mio-Pleistocene sedimentary sequence in the early hominid fossiliferous areas of the northern Chad Basin

Anne-Elisabeth Lebatard ^{1, 2} Didier L. Bourlès ¹ Regis Braucher ¹ Maurice Arnold ¹ Philippe Duringer ³ Marc Jolivet ⁴ Abderamane Moussa ³ Pierre Deschamps ¹ Claude Roquin ³ Julien Carcaillet ⁵ Mathieu Schuster ² Fabrice Lihoreau ⁶ Andossa Likius ⁷ Hassan Taisso Mackaye ⁷ Patrick Vignaud ² Michel Brunet ^{2, 8}

1 CEREGE - Centre européen de recherche et d'enseignement des géosciences de l'environnement

2 IPHEP - Institut International de Paléoprimatologie, Paléontologie Humaine : Evolution et Paléoenvironnement

3 IPGS - Institut de physique du globe de Strasbourg

4 GR - Géosciences Rennes

5 LGCA - Laboratoire de Géodynamique des Chaines Alpines

6 UMR ISEM - Institut des Sciences de l'Evolution de Montpellier

7 Unité de recherche de Paléontologie

8 Chaire de Paléoanthropologie et Préhistoire

Abstract : The concentrations of atmospheric cosmogenic 10Be normalized to the solubilized fraction of its stable isotope 9Be have been measured in the authigenic phase leached from silicated continental sediments deposited since the upper Miocene in the northern Chad Basin. This method is validated by the systematic congruence with the biochronological estimations based on the fossil mammal evolutive degree of faunal assemblages. The fifty-five authigenic 10Be/9Be ages obtained along 12 logs distributed along two West-East cross sections that encompass best representative Mio-Pliocene outcrops including paleontological sites show a systematic stratigraphic decrease when considering all studied sedimentary facies extending from the Pleistocene up to 8 Ma and allow performing geologic correlations otherwise impossible in the studied area. The resulting global sequence evidences and temporally specifies the succession of the main paleoenvironments that have developed in this region since the Miocene. Under the special conditions encountered in the northern Chad Basin, this study demonstrates that the authigenic 10Be/9Be ratio may be used as a dating tool of continental sedimentary deposits from 1 to 8 Ma. The half-life of 10Be theoretically allowing dating up to 14 Ma, it may have fundamental implications on important field research such as paleoclimatology and, through the dating of fossiliferous deposits in paleontology and paleoanthropology.

Keywords : cosmogenic nuclide beryllium-10 paleontology Hominidae paleoenvironments Chad Basin

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Journal articles

Domain :

Sciences of the Universe [physics] / Earth Sciences / Geochemistry

Environmental Sciences / Global Changes

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Submitted on : Wednesday, December 22, 2010 - 3:39:03 PM
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Application of the authigenic 10Be/9Be dating method to continental sediments: Reconstruction of the Mio-Pleistocene sedimentary sequence in the early hominid fossiliferous areas of the northern Chad Basin

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Application of the authigenic 10Be/9Be dating method to continental sediments: Reconstruction of the Mio-Pleistocene sedimentary sequence in the early hominid fossiliferous areas of the northern Chad Basin

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