Preliminary Results from Sediment Cores from Lake Bosumtwi, Ghana
Michael R. Talbot, D. A. Livingstone, Patricia G. Palmer, Jean Maley, John M. Mélack, Georgette Delibrias, Steinar Gulliksen
Abstract
Results are presented from the analysis of three sediment cores from Lake Bosumtwi, Ghana, using mineralogy, sedimentology, palynology and grass cuticle content. The longest core is 16.9 m long and spans approximately the last 27 500 years of the lake’s history. Apart from minerals of clastic origin, the sediments contain a variety of endogenetic and diagenetic minerals, particularly carbonates, with phosphates and zeolites also prominent in some sections. Mineral content and sedimentology are used to reconstruct the history of the lake. The oldest part of the sequence, from c.27 500 to 24 500 BP, is poorly understood, but seems to contain evidence of both high and low water levels. Between 23 000 and 19 500 BP the lake water was relatively dilute, but became more saline and alkaline between 19 000 and 16 000 BP when the lake level must have been low. Regressions of the lake are registered just before 13 500 BP, at c.3 750 BP and after 2 000 BP. Maximum lake level seems to have occurred between 9 000 and 4 000 BP, when the lake waters were dilute.