Direct geologic constraints on the timing of Late Holocene ice thickening in the Amundsen Sea Embayment, Antarctica

Keir Nichols*, Jonathan R. Adams, Katie Brown, Roger C. Creel, Marion A. McKenzie, Ryan A. Venturelli, Joanne S. Johnson, Dylan H. Rood, Klaus Wilcken, John Woodward, Stephen J. Roberts

*Corresponding author for this work

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Abstract

Constraining past West Antarctic Ice Sheet (WAIS) change helps validate numerical models simulating future ice sheet dynamics. Following rapid deglaciation during the mid-Holocene, ice near Thwaites Glacier was ∼35 m thinner than present; however, the timing of ice regrowth to its present configuration remains unknown. To fill this knowledge gap, we present cosmogenic nuclide exposure ages of cobbles from the surface of a moraine situated between Thwaites and Pope glaciers. We infer that the moraine formed and stabilized in the Late Holocene (∼1.4 ka) when a small glacier thickened. We also present a novel reconstruction of WAIS volume constrained by sea-level data, which demonstrates that moraine formation coincided with a large-scale WAIS readvance. Our new geologic constraints will help inform models of the solid Earth response to surface mass loading, improving our understanding of ice sheet dynamics in a vulnerable part of WAIS.
Original languageEnglish
Article numbere2024GL110350
Number of pages11
JournalGeophysical Research Letters
Volume51
Issue number24
Early online date19 Dec 2024
DOIs
Publication statusPublished - 28 Dec 2024

Keywords

  • Holocene
  • Thwaites glacier
  • geochronology
  • glacial geology
  • readvance
  • west Antarctic Ice Sheet

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