Depositional history and paleontology of the Lubur sandstone of northern Kenya: a record of Mesozoic tectonism in East Africa

Joseph J.W. Sertich, University of Utah Department of Geology and Geophysics, Salt Lake City, Utah, [email protected]

Understanding the age and depositional history of the Lubur sandstone of northern Kenya is critical to understanding the geologic history of the region and the early tectonic history of East Africa.  The Lubur sandstone consists of a poorly understood sequence of immature, arkosic sandstones and conglomerates deposited in a braided alluvial system in northern Kenya with characteristics of a potential hydrocarbon reservoir.  Macrovertebrate fossils recovered from the Lubur sandstone in the Lapurr Range indicate a Cretaceous age for the unit and suggest the deposits are related to early activity of the Cretaceous-Paleogene Anza Graben.  These fossils provide the only practical method of providing age constraint for the sediments and additional analysis of these specimens will further refine the age of the Lubur sandstone.  Further scrutiny of the deposits themselves, including detailed petrography, will assist in determining the provenance and depositional history of the sediments.  Association of the Lubur sandstone with the Anza Graben would provide a potential link between hydrocarbon bearing units of similar age in Sudan and southeast Kenya with implications for hydrocarbon reservoirs in northern Kenya.  A more complete understanding of the history of this important early feature in the evolution of the East African Rift Province will also add to our understanding of tectonic processes.