Stable isotope and C study of biogenic calcrete in a termite mound, Western Cape, South Africa, and its palaeoenvironmental significance |
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| Authors: | Alastair J Potts Jeremy J Midgley Chris Harris |
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| Institution: | aBotany Department, University of Cape Town, South Africa;bDepartment of Geological Sciences, University of Cape Town, South Africa |
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| Abstract: | 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 δ13C and δ18O values that show systematic changes with radiocarbon dates, which range from 33,629–36,709 to 21,676–23,256 cal yr BP. These dates confirm that these heuweltjies had been present in the landscape since the last glacial period. The decrease in δ13C and δ18O 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 C4 or CAM plants, occurred in the region during the time heuweltjie calcite precipitated. |
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| Keywords: | Calcrete heuweltjies Termite mounds Carbon and oxygen isotopes Western Cape Palaeoenvironment |
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