The Morphology and Genesis of Cold-Phase Diamicts in High Altitude Lake Sediments of Mount Kenya, Kenya

Abstract

Lake sediment cores spanning the last interglacial-glacial-present interglacial cycle have been recovered from Sacred Lake and Lake Nkunga on the northeastern flank of Mount Kenya, Kenya. Within these cores are diamicts which occur at the last interglacial-glacial transition (ca.110,000 yr BP) and between 58,000 and 48,000 yr BP. The occurrence of the diamicts (formed by active freeze-thaw processes in the lake catchments) is associated with periglacial and concurrent relatively humid conditions at the altitudes of the lakes. In addition, their temporal occurrence is correlated with abrupt low temperature extremes and/or rapid transition rates to lower temperature regimes at high latitude regions. Close modern corollaries of such sediments have been documented at higher altitude on Mount Kenya, but there is no known documentation of such sediments in the late Quaternary records of the tropical high mountains.