Variable Hydroclimate in the Suguta-Turkana Valley, Kenya during the Early Middle-Pleistocene Transition

The Early Mid-Pleistocene Transition (EMPT) between 1,200–700 ka represents a major global climate transition from dominantly 41,000-year to 100,000-year glacial cycles. The forces and mechanisms behind this transition, and the response of African environments, is not well understood. The active volcanism and tectonics of the East African Rift System (EARS) add complexity to environmental systems and can erase important proxy records, inhibiting studies of lacustrine dynamics. As a result, there is minimal understanding of how this transition impacted the region’s lake systems, with implications for hominin migration. At paleolake Suguta in the northern Kenya Rift, however, flood basalts cap lacustrine EMPT-aged deposits and help preserve these strata and their valuable paleoenvironmental record. This research presents a high-resolution reconstruction of hydrological change from approximately 930 to 830 ka during the EMPT at the Suguta-Turkana Valley in the northern Kenya Rift. Paleolake dynamics are reconstructed from a 41 m sedimentary section using diatom morphology, sedimentology, and x-ray fluorescence analysis. Lake levels varied during the EMPT, particularly from ~885–830 ka, ranging from deep stratified lakes, shallow, well-mixed lakes, and complete desiccation. This record identifies hydroclimate variability at several thousand year-resolution within the Suguta-Turkana Valley during the EMPT, illuminating a period where generally little is known about terrestrial environmental change.