Alexis Nutz's seminar, Aix-Marseille University

Facies and syn-rift sedimentary sequences of the Nachukui Formation (Turkana Depression, Rea, Kenya): Implications for Plio-Quaternary Paleoenvironments

Alexis Nutz's seminar, 2019


The Nachukui Formation (West Turkana, Kenya) is a syn-rift series more than 700 m thick including deep fluvial, deltaic, littoral and lacustrine deposits emplaced along the North Lake half-graben edge fault. Basin, in the northern depression of Turkana. It covers a period between ~ 4 and ~ 0.7 Ma making this succession an important archive of the Plio-Quaternary period in the northern depression of Turkana and the East African rift more generally.
For decades, the northern depression of Turkana has been a major site for different scientific communities. More than 500 fossils of hominids have been discovered, some of them corresponding to specimens of primary importance for the understanding of the evolution of the human line, and more than 100 archaeological sites are also referenced making this region a leading region for paleoanthropologists, paleontologists and archaeologists. On the other hand, for sedimentologists, the northern depression of Turkana provides exceptionally well exposed syn-rift deposits that provide a better understanding of the fundamental processes related to continental rifting and sedimentation patterns associated with rift basins. Indeed, the Omo group's plio-quaternary syn-rift sediments provide a continuous record of the evolution of an axial system (Shungura formation), a transverse ramp system (Koobi Fora formation) and a transverse system. with faulted edge (Nachukui Formation) within a continental rift basin.
Through this presentation, the results of recent investigations (2014-2018) on the Nachukui Formation will be presented. For the first time, the depositional environments have been analyzed over the entire succession, a complete sequential interpretation will be provided and a reconstruction of the lake level will be proposed for the period between ~ 4 and ~ 0.7 Ma. The different paleo The sedimentary environments that characterized the region will be presented to refine our understanding of the sedimentation patterns and paleo-environmental conditions that prevailed during the Plio-Quaternary. Finally, the forcings will be discussed and the conclusions published previously will be confronted with these new elements.