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Paleoenvironmental Reconstruction of the Turkana Basin through pedogenic carbonate analyses (1.9 to 1.2 Ma)
  • Catherine Beck
Catherine Beck
Hamilton College

Corresponding Author:[email protected]

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Eastern Africa contains a well-preserved pedogenic carbonate record, useful for contextualizing the paleoenvironment associated with key fossil and archeological evidence. One significant paleoanthropological discovery from the Turkana Basin in Kenya was Nariokotome Boy, one of the most complete examples of Homo erectus discovered to date. This site is directly associated with a paleo-Vertisol and the Natoo tuff, enabling stratigraphic correlation into outcrop records. Leveraging this opportunity, we analyzed stable isotopes of pedogenic carbonates (n=74) to study the paleoenvironmental conditions in the Turkana Basin for three time slices between 1.9 and 1.2 Ma. We interpret that the narrow range of δ18O values implies the presence of one main water source throughout the time interval. Variation in δ13C, with a standard deviation of 1.5‰ and range of 6.9‰, can thus be considered a function of landscape heterogeneity rather than changing water source. Woody cover estimates from the paleosols within this study interval suggest this area was a wooded grassland despite a significant first-order paleoenvironmental change from a marginal lacustrine environment to a fluvially-dominated one. While our record cannot resolve variability on a millennial scale, the lack of significant long term trends in percent woody cover suggest that Nariokotome Boy and other hominin communities inhabited a paleoenvironment which was relatively stable in terms of vegetation composition despite a major lacustrine regression.