Paleoenvironmental Reconstructions of Holocene Lacustrine Highstands in a Rifts Basin, Lake Turkana, Kenya

Catherine C. Beck
Rutgers University, Dept of Earth and Planetary Science
New Brunswick, NJ, USA
[email protected]

Long famous for its Plio-Pleistocene hominin record, in recent years the Turkana Basin, Kenya has become a hotspot for petroleum exploration. While most exploration is focused on Eocene-Miocene sediments which do not outcrop extensively in the basin, prevalent Holocene deposits are a valuable resource as they provide a window into lacustrine deposition into continental African rift basins. By combining sedimentology, stratigraphy, ostracod paleoecology, and lateral facies relationships of Holocene outcrops from Kabua Gorge, this research contributes to paleoenvironmental and paleolimnological reconstructions of Lake Turkana during Holocene highstand events. Fieldwork was conducted at Kabua Gorge to measure sections, map geology, and collect sediment and dating samples. Sections and mapping were used to construct facies relationships in order to identify different environments such as lacustrine, deltaic, fluvial, and fringing wetlands. Sediment samples will be picked for ostracods to study changes in species assemblages and total abundance through each of the three Holocene highstand events recorded at Kabua. Dating samples include molluscs, ostracods, and charcoal and will be used to a) document the reservoir effect by comparing dates from various materials, and b) better constrain the timing of lacustrine highstands. Preliminary results from this project indicate that fringing wetlands are a significant sink for carbon in this depositional setting as indicated by an extensive black shale unit. Paleolimnological/paleoenvironmental studies of the Turkana Basin will be important for better understanding, and therefore being able to locate and predict, areas with promising Cenozoic source rocks both in East Africa and worldwide.

AAPG Search and Discovery Article #90183©2013 AAPG Foundation 2013 Grants-in-Aid Projects