Antarctic ice sheet re-advance during the Antarctic Cold Reversal identified in the Western Ross Sea (Antarctica)

Despite much progress over the past decade, reconstructing the details and timing of Antarctic Ice Sheet (AIS) retreat remains a matter of debate, even in well surveyed areas such as the northwestern sector of the Ross Sea (e.g., Halberstadt et al., 2016; Greenwood et al., 2018; Prothro et al., 2020). There, Grounding Zone Wedges (GZWs) show how the Antarctic Ice Sheet (AIS) has retreated since the Last Glacial Maximum (LGM). Well-known evidence includes the GZW north of Coulman Island, testifying to the maximum LGM extent, and the terrestrial dating from Terra Nova Bay and Scott Coast, documenting time steps of the Holocene deglaciation. Here we present a new reconstruction for the Drygalski Basin based on geomorphological and geophysical data. The data suggests a short-lived pause and re-advance of the grounded ice during the Antarctic Cold Reversal (ACR – 14.7-13 ka; Baroni et al. 2022). The evidence for re-advance includes GZWs on the eastern and western flanks of the basin, that partly bury mega-scale glacial lineations associated with the Coulman Island GZW. Re-advance during the ACR suggests that relatively small-amplitude and short-duration climate oscillations exerted a significant impact on the extent and thickness of the grounded ice during the Last Glacial Termination.