PALEOPEDOLOGY AND PALEOCLIMATE OF THE PLIO-PLEISTOCENE CHEMERON FORMATION, BARINGO BASIN, KENYA

The Baringo Basin of central Kenya exhibits the most continuous sedimentary record of the Neogene in eastern Africa. The Chemeron Formation of the Baringo Basin preserves diverse faunal assemblages—including hominins—that span major global climate events across the Pliocene to early Pleistocene. Abundant paleosols preserved throughout the Chemeron Formation stratigraphy provide an in-situ substrate for reconstructing local climate, vegetation, and landscape processes from proxies. Here we describe ongoing field and laboratory analyses, including bulk elemental characterization of at least 28 individual paleosols and a variety of parent materials that include basalt, fluvial sandstone, and lacustrine siltstone. Most paleosols show moderate deviation from parent materials, have evidence of seasonally variable drainage, and demonstrate relatively limited diagenetic overprinting. Paleosols developed on fluvial parent materials tend to be more weathered than those formed on alluvial materials (i.e., debris flows) or exposed lacustrine beds. Initial results suggest potential long-term, secular drying occurred from the early Pliocene through the early Pleistocene, with shorter-term variations in hydroclimate. However, the climate state for the terrestrial portions of the Chemeron Formation suggest subhumid conditions prevailed and could have supported a wide range of habitats. Our continuing efforts include analyses of pedogenic carbonate formation temperatures from clumped isotopes (Δ₄₇), development of paleovegetation records from δ¹³C analyses on pedogenic carbonates and organic matter, and mass-balance analysis of major and minor elemental oxides to track silicate weathering.