Significantly reduced ice coverage in Greenland and West Antarctica during the warmer-than-present Pliocene could account for ~10m of global mean sea level rise. Any sea level increase beyond this would
require contributions from the East Antarctic Ice Sheet (EAIS). Previous studies have presented low-resolution geochemical evidence from the geological record, suggesting repeated ice advance and retreat in
low-lying areas of the EAIS such as the Wilkes Subglacial Basin.
However, the rates and mechanisms of retreat events are less well
constrained. Here we present orbitally-resolved marine detrital sediment provenance data, paired with ice-rafted debris and productivity
proxies, during three time intervals from the middle to late
Pliocene at IODP Site U1361A, offshore of the Wilkes Subglacial Basin. Our new data reveal that Pliocene shifts in sediment provenance
were paralleled by increases in marine productivity, while the onset of such changes was marked by peaks in ice-rafted debris mass accumulation rates. The coincidence of sediment provenance and marine
productivity change argues against a switch in sediment delivery
between ice streams, and instead suggests that deglacial warming triggered increased rates of iceberg calving, followed by
inland retreat of the ice margin. Timescales from the onset
of deglaciation to an inland retreated ice margin within the
Wilkes Subglacial Basin are on the order of several thousand years. This geological evidence corroborates retreat rates determined from
ice sheet modelling, and a contribution of ~3 to 4m of equivalent sea
level rise from one of the most vulnerable areas of the East Antarctic
Ice Sheet during interglacial intervals throughout the middle
to late Pliocene.