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The Cryosphere An interactive open-access journal of the European Geosciences Union
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Discussion papers
https://doi.org/10.5194/tc-2019-64
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/tc-2019-64
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: research article 14 May 2019

Submitted as: research article | 14 May 2019

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This discussion paper is a preprint. A revision of this manuscript was accepted for the journal The Cryosphere (TC) and is expected to appear here in due course.

New Last Glacial Maximum Ice Thickness constraints for the Weddell Sea sector, Antarctica

Keir A. Nichols1, Brent M. Goehring1, Greg Balco2, Joanne S. Johnson3, Andrew A. Hein4, and Claire Todd5 Keir A. Nichols et al.
  • 1Department of Earth and Environmental Sciences, Tulane University, New Orleans, 70118, LA, USA
  • 2Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, 94709, CA, USA
  • 3British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge, CB3 0ET, UK
  • 4School of GeoSciences, University of Edinburgh, Drummund Street, Edinburgh, EH8 9XP, UK
  • 5Department of Geosciences, Pacific Lutheran University, Tacoma, 98447, WA, USA

Abstract. This paper describes new Last Glacial Maximum (LGM) ice thickness constraints for three locations spanning the Weddell Sea Embayment (WSE) of Antarctica. Samples collected from the Shackleton Range, Pensacola Mountains, and the Lassiter Coast constrain the LGM thickness of the Slessor Glacier, Foundation Ice Stream, and grounded ice proximal to the modern Ronne Ice Shelf Edge on the Antarctic Peninsula, respectively. Previous attempts to reconstruct LGM-to-present ice thickness changes around the WSE used measurements of long-lived cosmogenic nuclides, primarily 10Be. An absence of post-LGM apparent exposure ages at many sites led to LGM thickness reconstructions that were spatially highly variable, and inconsistent with flowline modeling. Estimates for the contribution of the ice sheet occupying the WSE at the LGM to global sea level since deglaciation vary by an order of magnitude, from 1.4 to 14.1 m of sea level equivalent. Here we use a cosmogenic nuclide, in situ produced 14C, to evaluate the possibility that sites with no post-LGM exposure ages are biased by cosmogenic nuclide inheritance due to surface preservation by cold-based ice and nondeposition of LGM-aged drift. Our measurements show that the Slessor Glacier was between 310 and 650 m thicker than present at the LGM. The Foundation Ice Stream was at least 800 m thicker, and ice on the Lassiter Coast was at least 385 m thicker than present at the LGM. With evidence for LGM thickening at all of our study sites, our in situ 14C measurements indicate that the long-lived nuclide measurements of previous studies were influenced by cosmogenic nuclide inheritance. Our LGM thickness constraints point toward a modest contribution from the Weddell Sea Embayment to global sea-level since deglaciation, with an estimated range of 2.2 to 5.8 m.

Keir A. Nichols et al.
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Interactive discussion
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Status: closed
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Keir A. Nichols et al.
Keir A. Nichols et al.
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Short summary
We studied the history of ice masses at three locations within the Weddell Sea embayment, Antarctica. We measured rare isotopes in material sourced from mountains overlooking the Slessor Glacier, Foundation Ice Stream, and smaller glaciers on the Lassiter Coast. We show that ice masses were between 385 and 800 m thicker than they are at present. The ice masses were both hundreds of metres thicker and remained thicker closer to the present than was previously thought.
We studied the history of ice masses at three locations within the Weddell Sea embayment,...
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