Geochemistry of the Fejej Tuffs (South Omo, Ethiopia), their Tephrostratigraphical Correlation with Plio-Pleistocene Formations in the Omo-Turkana Basin

The FJ-1 Tuff and three additional isolated outcrops of volcanic tuffs listed in the Fejej area (South Omo, Ethiopia) are associated with a single volcanic event and correspond to the same ash deposit subsequently truncated by erosion. Data from new chemical analyses given by X-ray fluorescence allow correlation of these tuffs with the Borana Tuff of the Koobi Fora Formation, which is itself correlated with a tuff in the Upper G member or with the H-1 tuff of the Shungura formation. The geochronological assessment of this tephra is in agreement with previous magnetostratigraphical and biostratigraphical studies, attributing the Fejej FJ-1 Tuff to between 1.95 to 1.90. Ma. © 2011 Académie des sciences.