Preprints
https://doi.org/10.5194/egusphere-2023-1397
https://doi.org/10.5194/egusphere-2023-1397
28 Jul 2023
 | 28 Jul 2023

The staggered retreat of grounded ice in Ross Sea, Antarctica since the LGM

Matthew A. Danielson and Philip J. Bart

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.

Matthew A. Danielson and Philip J. Bart

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-1397', Anonymous Referee #1, 12 Sep 2023
    • AC1: 'Reply on RC1', Matthew Danielson, 01 Oct 2023
  • RC2: 'Comment on egusphere-2023-1397', Anonymous Referee #2, 24 Sep 2023
    • AC2: 'Reply on RC2', Matthew Danielson, 01 Oct 2023

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-1397', Anonymous Referee #1, 12 Sep 2023
    • AC1: 'Reply on RC1', Matthew Danielson, 01 Oct 2023
  • RC2: 'Comment on egusphere-2023-1397', Anonymous Referee #2, 24 Sep 2023
    • AC2: 'Reply on RC2', Matthew Danielson, 01 Oct 2023
Matthew A. Danielson and Philip J. Bart
Matthew A. Danielson and Philip J. Bart

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Short summary
The post-last glacial maximum retreat of the West Antarctic Ice Sheet in Ross Sea was greater than for any other Antarctic sector. Here we combined the available dates of retreat with new mapping of sediment deposited by the ice sheet during overall retreat. Our work shows that the post-last glacial maximum retreat through Ross Sea was uneven and not uniform. This uneven retreat can cause instability in the present-day Antarctic ice sheet configuration and lead to future runaway retreat.