ON THE LOWER NACHUKUI FORMATION AT LOMEKWI, WEST TURKANA, KENYA: NEW INSIGHTS ON THE PALEOENVIRONMENT, STRATIGRAPHY, AND ENVIRONMENTAL FRAMEWORK

The lower Nachukui Formation around Lomekwi in northern Kenya presents a unique opportunity to understand the interplay of tectonics and climate in shaping the paleoenvironment of the Turkana Basin. This research focuses on the Late Pliocene stratigraphy and environmental context of the Lomekwi Member and environs, highlighting significant fluvial and lacustrine interactions and their implications for regional paleoenvironmental changes.

Fieldwork included detailed stratigraphic section measurements and various sedimentological analyses, revealing a complex sedimentary architecture influenced by both tectonic and climatic factors. Our findings emphasize the significance of fluvial systems in sediment transport and the role of lake expansions and contractions driven by climatic variations. Previous studies have given either very broad, regional overviews encompassing extensive areas and vast temporal ranges or hyper-focused local examinations to accompany fossil or artifact discoveries. Both approaches are necessary and form the foundation of our research and the existence of this very symposium.

Here, we adopt a 'Goldilocks' approach, striking a balance by focusing on a specific locality and timeframe that is neither too broad nor too narrow, thereby providing a more detailed examination of what we consider compelling geology. We expand the region’s published stratigraphy, with sections measured and correlated in the Lonyumun and Kataboi Members, and add to the impressive catalog of Lomekwi stratigraphy, with sections measured in the Kangatakuseo area, as well as along the Lomekwi type section. Fieldwork has also revealed previously undescribed exposures of Etheria elliptica in life position and provided evidence of river dynamics. We also expand the region’s facies types and associations, with new insights into pebbly mudstone, alluvial fans, and biogenic sediments. This burgeoning research into the enigmatic late Pliocene provides potential drivers for the environment and ecology that gave rise to the genus Homo.