Luminescence chronology and sedimentology of the Maputaland barrier–dune complex (South Africa): new insights into MIS 5e dune construction and Late Holocene reactivation

Coastal dune systems along the Maputaland coastal plain serve as key archives of the interaction between sea-level fluctuations, wind regimes, and sediment recycling along the southeastern African continental margin. This study presents an integrated analysis of a barrier–dune section at Richards Bay, KwaZulu-Natal, South Africa. By combining luminescence dating with grain-size and mineralogical analyses, three distinct phases of aeolian accumulation are identified, thereby providing improved chronological control and a reassessment of the area's palaeoenvironmental setting. The section records two closely spaced aeolian units deposited during the last interglacial (MIS 5e). The basal white, quartz-rich dune sands yield an age of ∼129 ± 7 ka and comprise well-sorted aeolian deposits. Their heavy-mineral assemblages are dominated by stable, resistant phases, consistent with distal sediment supply and extensive reworking of shelf and nearshore material under high sea-level conditions, although weathering and hydraulic sorting may also have contributed. The overlying strong brown, ferruginous sands yield an overlapping age of ∼117 ± 7 ka, yet display a contrasting mineralogical signature. Enrichment in less stable phases suggests a greater contribution from more proximal sources and/or modified transport pathways, while abundant secondary Fe oxides indicate substantial post-depositional alteration and intervals of surface stabilisation. The uppermost pale brown, well-sorted aeolian sands, deposited during the Late Holocene, record recent dune accretion or remobilisation of previously deposited material, with stabilisation occurring within the last ∼200 years. These results provide new insights into the evolving environmental conditions and long-term dynamics of coastal dune systems along the southeastern African margin.