ALBERT

Description: The subglacial geology in Wilkes Land, East Antarctica is masked by thick ice and remains largely unexplored. Yet the underlying crustal architecture records evidence of repeated supercontinent cycles and provides the geological template for the evolution of the Antarctic Ice Sheet. Sediment eroded from under the ice is ultimately deposited in the ocean, such that marine sediment can be used to characterise the adjacent subglacial geology. We use detrital grain morphology, geochemistry and isotopic data from a kasten core to construct a new marine sediment provenance record for the continental slope of central Wilkes Land, and provide new isotopic signatures from proximal coastal outcrops for comparison. We establish the source rock type, age and provenance, and the associated transport pathways and mechanisms responsible for detrital sediment input from 23.5 ka to present. A principally igneous source is revealed with dominant age populations between c. 1200-1100 Ma and c. 1600-1300 Ma, characteristic of the proximal Banzare, Nuyina and Wilkes Provinces. The detrital geochronology suggests no change in sediment provenance over the last 23.5 ka, despite major ice sheet retreat during this time. A minor c. 700-500 Ma detrital age population unknown from the central Wilkes region was likely transported westward via icebergs to the core site. These findings broadly correspond with earlier interpretations of the subglacial geology and erosion rates at the base of the ice sheet predicted from two ice sheet models, demonstrating the value of sediment provenance studies for uncovering proximal subglacial geology and reconstructing past ice sheet configurations.