Late Pleistocene landscape response to climate change: eolian and alluvial fan deposition, Cape Liptrap, southeastern Australia

Abstract

Sea cliffs along the western coast of Cape Liptrap at Arch Rock provide nearly continuous exposure of calcareous eolianites dated at 68–112 ka (five optically stimulated luminescence (OSL) ages). Calcareous eolian deposition began immediately after the last interglacial marine highstand (Oxygen Isotope Stage (OIS) 5e) and continued during sea level fall until the beginning of OIS 4. West-southwesterly winds transported calcareous sand across ∼12 km of exposed continental shelf by the beginning of OIS 4. A brief period of cold, arid, windy continental climate with ephemeral, but intense, surface runoff immediately preceded the Last Glacial Maximum (LGM). This resulted in fluvial reworking of the calcarenites into an alluvial fan dated at 23–25 ka (four OSL ages). The fan overlies peat dated at 25,279 yr cal BP and is capped by a paleosol dated at 6010 yr cal BP. Concurrent eolian reworking by northwesterly winds of siliceous sediments on marine terraces along the eastern and central portion of Cape Liptrap formed siliceous longitudinal dunes with ages ranging from 19 to 24 ka (five OSL ages). The phase of maximum landscape instability at Cape Liptrap coincides with solar insolation and air temperature minima and preceded the LGM by several thousand years.