Orbital control of Pleistocene euxinia in Lake Magadi, Kenya

Lake Magadi is an internally drained, saline and alkaline terminal sump in the southern Kenya Rift. Geochemistry of samples from ~200 m core representing past ~1 m.y. lake’s history shows some highest concentrations transition metals metalloids ever reported lacustrine sediment, including redox-sensitive elements molybdenum, arsenic, vanadium. Elevated these represent times when hypolimnion was euxinic—that is, anoxic, saline, sulfide-rich. Euxinia common after ca. 700 ka, that tended to occur during intervals high orbital eccentricity. These were likely high-frequency hydrologic changes favored repeated episodes euxinia sulfide precipitation. High-amplitude environmental fluctuations at peak eccentricity impacted water balance terrestrial habitats resource availability for early hominins. are associated with important events human evolution, first appearance Middle Stone Age technology between 500 320 ka