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

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

来源：Earth and Planetary Science Letters, 2010, 297(1-2): 57-70.

DOI：10.1016/j.epsl.2010.06.003

• cosmogenic nuclide
• beryllium-10
• paleontology
• Hominidae
• paleoenvironments
• Chad Basin

The concentrations of atmospheric cosmogenic Be-10 normalized to the solubilized fraction of its stable isotope Be-9 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 Be-10/Be-9 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 fades 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 Be-19/Be-9 ratio may be used as a dating tool of continental sedimentary deposits from 1 to 8 Ma. The half-life of Be-10 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.

• 出版日期2010-8-15