The staggered retreat of grounded ice in Ross Sea, Antarctica since the LGM
Abstract. The post-LGM retreat of the West Antarctic Ice Sheet (WAIS) in Ross Sea was greater than for any other Antarctic sector. Here we combined the available chronology of retreat with new mapping of seismically-resolvable grounding zone wedges (GZWs). Mapping GZWs is important because they record the locations and durations of former stillstands in the extent of grounded ice for individual ice streams during the overall retreat. Our analysis shows that the longest stillstands occurred early in the deglacial and had millennial durations. Stillstands ended abruptly with retreat distances measured in the tens to hundreds of kilometers creating deep embayments in the extent of grounded ice across Ross Sea. The location of embayments shifted through time. The available chronological data shows that cessation of WAIS stillstands was highly asynchronous across at least five thousand radiocarbon years. There was a general shift to shorter stillstands as the deglacial progressed. Asynchronous collapse of individual catchments over the course of the post-LGM suggests that the Ross Sea sector would have contributed to multiple episodes of relatively-small amplitude, sea-level rise. The high sinuosity of the modern ground zone in Ross Sea suggests that this style of retreat persists.
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