Abstract

Intricate morphology, combined with relatively soft and soluble calcite mineralogy, make foraminifera tests sensitive indicators of grain abrasion during transport in beach and coastal dune systems. Here, the extent of abrasion and dissolution of foraminifera tests is used to elucidate the relative ages and transport paths of sand from the Sixteen Mile Beach and 24-km-long Yzerfontein-Geelbek Holocene dune cordon on the west coast of southern Africa, located 80 km north of Cape Town. Foraminifera tests collected in rocky pools along the beach are well preserved with complete or nearly complete tests. Foraminifera tests recovered from adjacent beach sands show incipient signs of abrasion and are fragmented moderately and abraded from transport along the shoreface. Wind-blown foraminifera tests along the Yzerfontein-Geelbek active dune cordon show increasing signs of abrasion, corroded surfaces, and partly dissolved walls up to 18 km from the beach source. Between 18 km and 24 km from the beach source, most biogenic calcareous grains— shell fragments and foraminifera tests—in dune sand with an estimated maximum age of 4,500 years have been destroyed by physical and chemical weathering.

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