Multiphase late Quaternary aeolian sediment accumulation in western South Africa: Timing and relationship to palaeoclimatic changes inferred from the marine record

Abstract

Extensive aeolian deposits exist along the western margin of South Africa from Cape Town through to the Namib Sand Sea, and represent a significant palaeoenvironmental archive recording millennial-scale patterns of regional and hemispheric environmental change. To establish the timing of dune development, this study applies optically stimulated luminescence (OSL) dating techniques to the aeolian features of the west coast. In total, 35 samples were obtained from six dune cores along a north–south transect extending from Elands Bay (32°26′S, 18°14′E) to Kleinsee (29°14′S, 16°59′E). Ages from these dunes exhibit five distinct peaks, suggesting phases of activity/deposition at 4–5, 16–24, 30–33, 43–49 and 63–73 ka. The spatial and temporal extent of the data have allowed for correlations to be made with evidence from marine cores from the Southeast Atlantic, and a more coherent regional environmental history to be developed. Results suggest that: (1) environmental changes in this region are strongly linked to variations in wind strength and atmospheric circulation systems during the late Quaternary; and (2) luminescence ages from aeolian deposits cannot necessarily be equated with periods of increased aridity, with other factors such as wind strength and sediment supply being of critical importance.