An isotopic study of a fluvial-lacustrine sequence: The Plio-Pleistocene koobi fora sequence, East Africa

T.E. Cerling; J. R. Bowman; J. R. O’Neil

doi:10.1016/0031-0182(88)90104-6

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An isotopic study of a fluvial-lacustrine sequence: The Plio-Pleistocene koobi fora sequence, East Africa

T.E. Cerling·J. R. Bowman·J. R. O’Neil

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Abstract

Stable isotopic analyses of Plio-Pleistocene and modern sediments in the fluvial-lacustrine system occupying the Turkana Basin, East Africa provide constraints on the paleoenvironmental and diagenetic histories of the Pliocene through the Recent sediments in the basin. The δ 13 C values for carbonates in lacustrine sediments range from −15 to +22‰ relative to PDB, depending on the varying proportions of CO 2 from the atmospheric reservoir and from various metabolic sources. The δ 18 O values of carbonates in lacustrine sediments indicate that the isotopic composition of paleolake water varied by over 10‰ from the Pliocene to the present. The δ 13 C values for pedogenic carbonates record paleoccologic variations and suggest that C 4 plants did not become well established in the preserved depositional parts of the basin until about 1.8 myr ago. The δ 18 O values pedogenic carbonates suggest a range of over 10‰ for the isotopic composition of soil water during this interval. They also suggest a period of major climatic instability from about 3.4 to 3.1 myr and at about 1.8 myr. Together, the δ 13 C and δ 18 O values of pedogenic carbonates indicate that the present conditions are as arid and hot as any that had prevailed during deposition of these Plio-Pleistocene sediments.

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Palaeogeography, Palaeoclimatology, Palaeoecology Article

Source-reported bounding extent: 2.3585266206236923° to 6.06521959485184° latitude; 35.45552515509482° to 39.05147077987755° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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T.E. Cerling, J. R. Bowman, J. R. O’Neil. 1988. An isotopic study of a fluvial-lacustrine sequence: The Plio-Pleistocene koobi fora sequence, East Africa. https://doi.org/10.1016/0031-0182(88)90104-6

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