Late Quaternary glacial-interglacial cycle of climatic and environmental change on Mount Kenya, Kenya

Sediments from Sacred Lake and Lake Nkunga on the northeastern flank of Mou nt Kenya have a sequential palaeoclimatic and palaeoenvironmental record co vering most of the Late Quaternary period: from ca 115 to 0 ka. Most of the Late Quaternary period (110 to 14 ka glacial period) was characterised by terrestrial C-4, vegetation types (grassland) at higher altitudes and mixed C-3-C-4 (grassland with scattered trees and shrubs) vegetation types at lo wer altitudes, while low, productivity-related C-13 discrimination occurred in the aquatic environment. The last interglacial and Holocene vegetation consisted of C-3, forest-type elements, and high C-13 discrimination occurr ed in the aquatic environment. The period 14 to 9 ka is transitional to Hol ocene climatic conditions, with progressive expansion of terrestrial C-3, v egetation, and increased C-13 discrimination in the aquatic environment. Th ese changes occurred in step with, and were primarily driven by, palaeo-atm ospheric CO2 changes. Thus, the estimates of temperature depression in the tropics during the last glaciation need to be revised as they are probably overestimated. Regionally, the changes on Mount Kenya are coherent with tho se observed at other high altitude sites across the tropics. Globally, they show a high coherency with Milankovitch periodicities, and are coupled to ocean circulation changes and ice sheet growth and disintegration cycles in the North Atlantic. (C) 1999 Elsevier Science Limited. All rights reserved .