Morphotectonic evolution of the central Kenya rift flanks: Implications for late Cenozoic environmental change in East Africa

Abstract

The Kenya rift valley is the classic example of an active continental rift zone. We report the rift Rank cooling history based on a combination of previous apatite fission track (AFT) and new (U-Th)/He (AHe) data. Our results corroborate the Late Cretaceous rapid cooling episode of continent-wide significance revealed previously by AFT dating. Post-Cretaceous cooling of the eastern rift flank was slow with net cooling of 3400 to in central Kenya. This timing also largely coincides with the uplift of the Western Rift flanks in Uganda and Congo and with the change toward drier conditions and grassland-dominated vegetation in East Africa. We propose that the regional morphotectonic evolution of..