Late Quaternary linear dune accumulation and chronostratigraphy of the southwestern Kalahari: implications for aeolian palaeoclimatic reconstructions and predictions of future dynamics |
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| Institution: | 1. Center for Nuclear Technologies, Technical University of Denmark, DTU Risø Campus, DK-4000 Roskilde, Denmark;2. Institut de Recherche sur les Archéomatériaux, UMR 5060 CNRS – Université de Bordeaux, Centre de Recherche en Physique Appliquée à l''Archéologie (CRP2A), Esplanade des Antilles, Maison de l''archéologie, 33607 Pessac Cedex, France;3. Nordic Laboratory for Luminescence Dating, Department of Geoscience, Aarhus University, DTUNutech, Risø Campus, DK-4000 Roskilde, Denmark;1. Limnology Unit, Department of Biology, Ghent University. Ghent, Belgium;2. Division of Ocean and Climate Physics, Lamont-Doherty Earth Observatory, Columbia University. Palisades, NY, USA;3. Department of Earth Sciences, Royal Museum for Central Africa. Tervuren, Belgium;4. Institute of Earth Surface Dynamics, University of Lausanne. Lausanne, Switzerland;5. Institute of Geosciences, Sect. Meteorology, Rheinische Friedrich-Wilhelms-Universität Bonn. Bonn, Germany;6. School of Geography and the Environment, University of Oxford. Oxford, UK;7. Massachusetts Institute of Technology-Woods Hole Oceanographic Institution Joint Program in Oceanography. Cambridge, MA, USA;8. Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology. Cambridge, MA, USA;9. Division of Geological and Planetary Sciences, California Institute of Technology. Pasadena, CA, USA;10. School of Archaeology, Geography and Environmental Science, University of Reading. Reading, UK;1. School of Geography, Earth and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA, UK;2. Department of Environment and Geography, Macquarie University, Herring Road, North Ryde, NSW 2109, Australia;1. School of Geography and Environment, University of Oxford, South Parks Road, Oxford OX1 3QY, UK;2. Long Term Ecology Laboratory, Department of Zoology, University of Oxford, UK;3. Department of Environmental and Geographical Science, University of Cape Town, South Africa;1. Department of Meteorology and Centre for Past Climate Change, University of Reading, RG6 6BB, UK;2. Environmental Change Institute, University of Oxford, OX1 3QY, UK |
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| Abstract: | The linear dunes of the Kalahari, now largely inactive, have long been identified as having potential palaeoenvironmental significance. The application of optically stimulated luminescence (OSL) dating to these dunes in the 1990s provided the first chronology of aeolian accumulation in this region, though field methodologies and time-consuming multiple-aliquot laboratory protocols limited both the depth of sampling in dune bodies and the total number of samples dated.In order to permit a more thorough investigation of the potential of these dunes to preserve long chronological records, this intensive study presents 71 OSL ages from the linear dunes of the southwestern Kalahari at Witpan, South Africa, sampled with coring equipment at regular and frequent intervals down to bedrock.The earliest sand accumulation recorded at Witpan is at 104 ka, and in spatially discrete locations, other evidence of dune activity is recorded at 77–76, 57–52 and 35–27 ka. Although an inherently discontinuous archive, the linear dunes of the southwestern Kalahari have the potential to record multiple phases of dune construction. Following the Last Glacial Maximum there is near continuous evidence of dune-building, with a peak of accumulation recorded from 15 to 9 ka at five individual sites. This latter period is generally recognised from other proxy evidence as being unusually arid in this region, and such periods of dune activity are likely to be related to intensification of the continental anticyclone. During the Holocene, accumulation has continued at most sites sampled, albeit at a lesser intensity. This may imply that these dunes are presently not far from thresholds of activation. |
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