Visualizing the Geologic Evolution of the Southern Kenya Rift Through Remapping, Unit Correlation and Utilization of Age Dates

Guth, Alexandria L.¹, James R. Wood¹ (1) Michigan Technological University, Houghton, MI

The East African Rift Valley is a modern active rift that can serve as an analog for ancient continental rifting, including structure, sedimentation and temporal development. Using older quarter-degree maps from the Kenya Geological Survey (KGS), along with newer maps from the literature, as keys to interpreting the surface geology, the rift valley in the southwest corner of Kenya (covering approximately 3 square degrees, about 31,500 square kilometers, semi-centered on Lake Magadi) has been remapped using modern satellite imagery. This remapping allowed for the incorporation of newer geologic data in addition to the correction of base-map errors present in some of the KGS maps. Though covering a large area, the mapping retains a quadrangle level of detail and, when combined with age dates, allows us to create a series of maps showing the evolution of the southern Kenya rift from the Miocene to the present. Over 150 published age dates have been gathered from the literature covering geologic units from Lake Turkana to Kilimanjaro. Combined with the detailed digital geologic map we have produced, we can demonstrate the temporal development of the southern Kenya rift beginning with the Kishalduga formation which erupted approximately 12-15 million years ago, before rift-faulting commenced in this region, and proceeding to the more recent sedimentary deposits and present hydrothermal activity. All geologic mapping elements (formations, faults, etc.) have been correlated across older map boundaries and saved as individual digital files so that geologic units don't end artificially at degree boundaries within the remapped area and to facilitate future analysis.