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The Ellsworth Subglacial Highlands: inception and retreat of the West Antarctic Ice Sheet

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Author(s)

  • Neil Ross
  • Tom Jordan
  • Robert Bingham
  • Hugh F. J. Corr
  • F Ferraccioli
  • Anne Le Brocq
  • David Rippin
  • Andrew Wright
  • M. J. Siegert

Department/unit(s)

Publication details

JournalGeological Society of America Bulletin
DatePublished - 2014
Issue number1-2
Volume126
Number of pages13
Pages (from-to)3-15
Original languageEnglish

Abstract

Antarctic subglacial highlands are where the Antarctic ice sheets first developed and the ‘pinning points’ where retreat phases of the marine-based sectors of the ice sheet are arrested. Due to low ice velocities and limited rates of present-day change in the ice sheet interior, West Antarctic subglacial highlands have often been overlooked for detailed study. These regions have considerable potential, however, for establishing from where the West Antarctic ice sheet (WAIS) originated and grew, and its likely response to warming climates. While several highland regions exist beneath the WAIS, none have been identified firmly as ice-sheet seeding and pinning points. Here, we characterise the glacial morphology of the Ellsworth Subglacial Highlands (ESH), West Antarctica, from ground-based and aerogeophysical radio-echo sounding (RES) surveys. We document well-preserved classic features associated with restricted, dynamic, marine-proximal Alpine glaciation, with hanging tributary valleys feeding a significant over-deepened trough (the Ellsworth Trough, now containing Ellsworth Subglacial Lake) cut by valley (tidewater) glaciers. Fjord-mouth threshold bars down-ice of two overdeepenings define both the north and south termini of palaeo outlet-glaciers which cut and occupied the Ellsworth Trough. We also show how MODIS satellite imagery of the ice sheet surface reflects the gross subglacial morphology of the ESH. The imagery reveals numerous glaciated valleys, aligned sub-parallel to the Ellsworth Trough, terminating at the edge of deep former marine basins (e.g. Bentley Subglacial Trench). These data can be used to reconstruct the glaciological character of the ice masses that formed the proto-WAIS. The landscape predates the present ice sheet, and is likely to have been formed by a small dynamic ice-field, at times when the marine sections of the WAIS were absent. The ESH represent a major seeding centre of the palaeo-WAIS, and its margins represent the pinning point at which any future retreat of the marine-based Amundsen and Weddell Sea sectors of the WAIS would be arrested.

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