Stable isotope and 14C study of biogenic calcrete in a termite mound, Western Cape, South Africa, and its palaeoenvironmental significance

Late Quaternary terrestrial climate records from the semi-arid zone of the Western Cape of South Africa are rare. However, palaeoenvironmental information may be inferred from ancient termite mounds of the region. Calcrete lenses in these mounds have delta C-13 and delta O-18 values that show systematic changes with radiocarbon dates, which range from 33,629-36,709 to 21,676-23,256 cal yr BR These dates confirm that these heuweltjies had been present in the landscape since the last glacial period. The decrease in delta C-13 and delta O-18 from 33.629-36,709 to 21,676-23,256 cal yr BP indicates that climate information is recorded by the calcretes. It is suggested that a progressive decline in air temperature and an increase in moisture availability, and a decline in abundance Of C-4 or CAM plants, occurred in the region during the time heuweltjie calcite precipitated. (C) 2009 University of Washington. Published by Elsevier Inc. All rights reserved.