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The Cryosphere An interactive open-access journal of the European Geosciences Union
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We present chronologies from Darwin and Hatherton glaciers to better constrain ice-sheet retreat during the last deglaciation in the Ross Sector of Antarctica. We use a glacier flowband model and an ensemble of 3D ice sheet model simulations to show that (i) the whole glacier system likely thinned steadily from about 9–3 kyr BP, and (ii) the grounding line likely reached the Darwin-Hatherton Glacier System at about 3 kyr BP, which is ≥ 3.8 kyr later than was suggested by previous reconstructions.
Preprints
https://doi.org/10.5194/tc-2020-356
https://doi.org/10.5194/tc-2020-356

  15 Dec 2020

15 Dec 2020

Review status: this preprint is currently under review for the journal TC.

Holocene thinning and grounding-line retreat of Darwin and Hatherton Glaciers, Antarctica

Trevor R. Hillebrand1,a, John O. Stone1, Michelle Koutnik1, Courtney King2, Howard Conway1, Brenda Hall2, Keir Nichols3, Brent Goehring3, and Mette K. Gillespie4 Trevor R. Hillebrand et al.
  • 1Department of Earth and Space Sciences, University of Washington, Seattle, WA 98195, USA
  • 2Laboratory School of Earth and Climate Science and Climate Change Institute, University of Maine, Orono, ME 04469, USA
  • 3Department of Earth and Environmental Sciences, Tulane University, New Orleans, LA 70118, USA
  • 4Faculty of Engineering and Science, Western Norway University of Applied Sciences, Sogndal, 6856, Norway
  • anow at: Fluid Dynamics and Solid Mechanics Group, Los Alamos National Laboratory, Los Alamos, NM 87545, USA

Abstract. We present exposure ages of glacial deposits at three locations alongside Darwin Glacier and its tributary Hatherton Glacier that record several hundred meters of late Pleistocene to early Holocene thickening relative to present. As the grounding-line of the Ross Sea Ice Sheet retreated rapidly southward, Hatherton Glacier thinned steadily from about 9 kyr BP until about 3 kyr BP. Our data are equivocal about the maximum thickness and mid-to-early Holocene history at the mouth of Darwin Glacier, allowing for two possible deglaciation scenarios: (1) ~500 m of steady thinning from 9 kyr BP to 3 kyr BP, similar to Hatherton Glacier, or (2) ~950 m of thinning, with a rapid pulse of ~600 m thinning at around 5 kyr BP. We test these two scenarios using a 1.5-dimensional flowband model of Darwin and Hatherton Glaciers, forced by ice-thickness changes at the mouth of Darwin Glacier and evaluated by fit to the chronology of deposits at Hatherton Glacier. Our modeling shows that the constraints from Hatherton Glacier are consistent with the interpretation that the mouth of Darwin Glacier thinned steadily by ~500 m from 9 kyr BP to 3 kyr BP; rapid pulses of thinning at the mouth of Darwin Glacier are ruled out by the data at Hatherton Glacier. This contrasts with some of the available records from the mouths of other outlet glaciers in the Transantarctic Mountains, many of which thinned by hundreds of meters over roughly a one-thousand-year period in the early Holocene. The deglaciation histories of Darwin and Hatherton Glaciers are best matched by a steady decrease in catchment area through the Holocene, suggesting that Byrd and/or Mulock glaciers may have captured roughly half of the catchment area of Darwin and Hatherton Glaciers during the last deglaciation. An ensemble of three-dimensional ice-sheet model simulations suggest that Darwin and Hatherton Glaciers are strongly buttressed by convergent flow with ice from neighboring Byrd and Mulock glaciers, and by lateral drag past Minna Bluff, which could have led to a pattern of retreat distinct from other glaciers throughout the Transantarctic Mountains.

Trevor R. Hillebrand et al.

 
Status: open (until 09 Feb 2021)
Status: open (until 09 Feb 2021)
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Trevor R. Hillebrand et al.

Trevor R. Hillebrand et al.

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Short summary
We present chronologies from Darwin and Hatherton glaciers to better constrain ice-sheet retreat during the last deglaciation in the Ross Sector of Antarctica. We use a glacier flowband model and an ensemble of 3D ice sheet model simulations to show that (i) the whole glacier system likely thinned steadily from about 9–3 kyr BP, and (ii) the grounding line likely reached the Darwin-Hatherton Glacier System at about 3 kyr BP, which is ≥ 3.8 kyr later than was suggested by previous reconstructions.
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