Sediment provenance of the Wilderness barrier dunes, southern Cape coast, South Africa

Abstract

Trace-element geochemistry has been used to discern the provenance of sediments derived from geologically distinct sources found in a range of depositional settings. This study investigates whether this approach can also identify provenance signatures in sediments derived from clastic sedimentary rocks of similar origins, within a complex coastal transport environment. The potential local sediment sources of a coastal barrier dune in South Africa were analysed to assess their relationships with the barrier and whether these have varied with time. Results indicate that the oldest part of the barrier, partly formed during MIS 6 when sea levels were lower than at present, has a closer affinity to fluvial sediment provided by local rivers than either younger samples from the barrier″s seaward flank or the Holocene dunes atop its crest, both formed during sea-level highstands. Constraints on the timing of barrier formation provided by OSL dating proved helpful in discriminating between provenance and weathering signals.Terra Nova, 00, 000-000, 2010. © 2010 Blackwell Publishing Ltd.