High-resolution 40Ar/39Ar geochronology of the Koobi Fora Tuff Complex, Turkana Basin: Implications for the hominin bearing strata of the Early Pleistocene (1.6–1.4 Ma)

Abstract

Volcaniclastic ash deposits (tuffs) within the Turkana Basin in Kenya act as temporal markers to constrain the extensive fossil-rich sediments of the Koobi Fora Formation. By using geochemical fingerprinting and precise geochronology this study improves the temporal and spatial resolution of the Koobi Fora, Lower Koobi Fora and Karari Blue tuffs within the Koobi Fora Tuff Complex. Utilising a Bayesian approach to single-grain anorthoclase ages this study presents ages of 1.49257 ± 0.00186 (2σ) Ma for the Karari Blue Tuff, 1.49430 ± 0.00142 (2σ) Ma for the Koobi Fora Tuff and 1.51561 ± 0.00090 (2σ) Ma for the Lower Koobi Fora Tuff. These results provide highly precise (1.51561 ± 0.00090 Ma). ..