TITLE: VOLCANISM, TECTONIC UPLIFT AND DRAINAGE INCISION OF THE KENYA RIFT, EAST AFRICAN RIFT SYSTEM: MORPHO-TECTONIC ANALYSIS APPROACH

Understanding the uplift history of the Kenya Rift of the Eastern Branch of the East African Rift System (EARS) is fundamental for reconstructing geologic evolution, evaluating changes in the paleo-environments, and assessing resource potential of rift basins. However, the distribution patterns and timing of tectonic uplift and associated geomorphic expressions of rift propagation are not entirely understood. This work analyzed the fluvial landscape response to the tectonic uplift and climate shifting of the rift shoulders, with special attention to timing, location, and intensity of uplift episodes. This was addressed by: (1) estimating the long-term incision rate of the Kenya Rift by using previous geochronological and thermochronological data from the volcanic rocks since Neogene; (2) characterizing the distribution pattern of short-term incision by morpho-tectonic analysis, including knickpoint analysis and geomorphic proxies (normalized steepness, chi-integral, and R/S_R integrative); and (3) correlating the incision rates spatially and temporally with tectonic/climatic history and comparing these with other sectors of the Eastern Branch of the EARS. We found the long-term incision rates have a positive anomaly in the central part of the Kenya Dome with an average incision of ~300 mm/kyr, likely driven by interactions between mantle-driven process and rapid tectonic uplift. Also, we found from the geomorphic proxies southward decreasing pattern of the short-term incision rate, showing a more tectonically-active stage in the northern Kenya Rift than in the southern section, possibly related to the north-south migrating influence of the mantle plume.