In the East African Rift, the western margin of Lake Turkana (northern Kenya) exposes Mio-Plio-Pleistocene lake sediments with dated volcanic horizons constraining basin dynamics at the astronomical time scale. Since the late Pliocene, coastal archaeological sites have formed within the lacustrine dynamics. Here, lake levels are reconstructed from 2.4 to 1.7 Ma using sedimentary facies and water/depth-controlled sediment association. The lacustrine stratigraphy is measured with a total station, and cyclostratigraphy is derived from tephrochronology. The water depths are evaluated from paleochemical properties of lake sediments analyzed by inductively coupled plasma optical emission spectrometry and inductively coupled plasma mass spectrometry. Our reconstruction highlights that Lake Turkana rose during 100 ka insolation/eccentricity maxima periods in response to higher monsoonal inputs of the Omo River. However, Lake Turkana also expanded through an insolation minimum at 2.17-1.95 Ma. This asynchronous lake phase coincides with volcanic closure of the Omo River and Lake Turkana outflow sill to the east and the Indian Ocean. An archaeological hiatus occurs during this endorheic lake phase, and alkalinity increases at the beginning of the hiatus. The lake rose again during insolation/eccentricity maxima at 1.9-1.7 Ma, and a new outflow sill opened to the west and the Nile basin. Hominin coastal occupations return during this exorheic/freshwater lake phase.
1.French Natl Inst Prevent Archaeol Res, 12 Rue Louis Maggiorini, F-69500 Lyon, France 2.Sorbonne Univ, Musee Homme, UMR 7194, CNRS,MNHN, 17 Pl Trocadero, F-75116 Paris 16, France 3.French Natl Inst Prevent Archaeol Res, 13 Rue Negoce, F-31650 St Orens De Gameville, France 4.Rutgers State Univ, Dept Earth & Planetary Sci, Piscataway, NJ 08854 USA 5.Rutgers State Univ, Dept Anthropol, New Brunswick, NJ 08901 USA 6.Rutgers State Univ, Ctr Human Evolutionary Studies, New Brunswick, NJ 08901 USA 7.Carleton Coll, Dept Geol, Northfield, MN 55057 USA 8.SUNY Stony Brook, Turkana Basin Inst, Stony Brook, NY 11794 USA 9.Univ Paris Ouest Nanterre, CNRS, UMR 7055, Prehist & Technol, 21 Allee Univ, F-92023 Nanterre, France
Recommended Citation:
Boes, Xavier,Prat, Sandrine,Arrighi, Vincent,et al. Lake-level changes and hominin occupations in the arid Turkana basin during volcanic closure of the Omo River outflows to the Indian Ocean[J]. QUATERNARY RESEARCH,2019-01-01,91(2):892-909