Holocene thinning of Darwin and Hatherton glaciers, Antarctica, and implications for grounding-line retreat in the Ross Sea

Journal Article · Tue Jul 20 00:00:00 EDT 2021 · The Cryosphere (Online)

DOI:https://doi.org/10.5194/tc-15-3329-2021· OSTI ID:1812668

Hillebrand, Trevor R. ^[1]; Stone, John O. ^[2]; Koutnik, Michelle ^[2]; King, Courtney ^[3]; Conway, Howard ^[2]; Hall, Brenda ^[3]; Nichols, Keir ^[4]; Goehring, Brent ^[4]; Gillespie, Mette K. ^[5]

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1. Univ. of Washington, Seattle, WA (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2. Univ. of Washington, Seattle, WA (United States)
3. Univ. of Maine, Orono, ME (United States). Climate Change Inst.
4. Tulane Univ., New Orleans, LA (United States)
5. Western Norway Univ. of Applied Sciences, Songdal (Norway)

Chronologies of glacier deposits in the Transantarctic Mountains provide important constraints on grounding-line retreat during the last deglaciation in the Ross Sea. However, between Beardmore Glacier and Ross Island – a distance of some 600 km – the existing chronologies are generally sparse and far from the modern grounding line, leaving the past dynamics of this vast region largely unconstrained. We present exposure ages of glacial deposits at three locations alongside the Darwin–Hatherton Glacier System – including within 10 km of the modern grounding line – that record several hundred meters of Late Pleistocene to Early Holocene thickening relative to present. As the ice sheet grounding line in the Ross Sea retreated, Hatherton Glacier thinned steadily from about 9 until about 3 ka. Our data are equivocal about the maximum thickness and Mid-Holocene to Early Holocene history at the mouth of Darwin Glacier, allowing for two conflicting deglaciation scenarios: (1) ~500 m of thinning from 9 to 3 ka, similar to Hatherton Glacier, or (2) ~950 m of thinning, with a rapid pulse of ~600 m thinning at around 5 ka. We test these two scenarios using a 1.5-dimensional flowband model, forced by ice thickness changes at the mouth of Darwin Glacier and evaluated by fit to the chronology of deposits at Hatherton Glacier. The constraints from Hatherton Glacier are consistent with the interpretation that the mouth of Darwin Glacier thinned steadily by ~500 m from 9 to 3 ka. 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 1000-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.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: National Science Foundation (NSF); USDOE
• Grant/Contract Number: 89233218CNA000001
• OSTI ID: 1812668
• Report Number(s): LA-UR--20-29852
• Journal Information: The Cryosphere (Online), Journal Name: The Cryosphere (Online) Journal Issue: 7 Vol. 15; ISSN 1994-0424
• Publisher: Copernicus Publications, EGU
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
97 MATHEMATICS AND COMPUTING