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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• 作者：Anne-Elisabeth Lebatard ; Didier L. Bourlè ; s ; Ré ; gis Braucher ; Maurice Arnold ; Philippe Duringer ; Marc Jolivet ; Abderamane Moussa ; Pierre Deschamps ; Claude Roquin ; Julien Carcaillet ; Mathieu Sc
• 关键词：cosmogenic nuclide ; beryllium-10 ; paleontology ; Hominidae ; paleoenvironments ; Chad Basin
• 刊名：Earth and Planetary Science Letters
• 出版年：2010
• 出版时间：15 August 2010
• 年：2010
• 卷：297
• 期：1-2
• 页码：57-70
• 全文大小：2819 K

文摘

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.