A 10Be Based Deglacial Chronology of the McMurdo Sound Region, West Antarctica
Abstract
The Ross Ice Shelf is the largest ice shelf on Antarctica and is fed primarily by the West Antarctic Ice Sheet (WAIS). Surface exposure dates from till and moraines in the McMurdo Sound and Dry Valleys region indicate that the Ross Ice Shelf thickened during the Last Glacial Maximum (LGM), due to extensive grounding on the continental shelf, which led to ice sheet advance into the Dry Valleys. Since the Ross Ice Shelf is fed by the WAIS, understanding the deglacial history of this region provides better constraints on the glacial history of the WAIS since the LGM. We sampled nearly 200 erratics from glacial deposits around McMurdo Sound to develop a 10Be based glacial chronology to address the following questions. (1) What was the upper limit of grounded ice in the region during the LGM? (2) When did ice begin to retreat from its LGM extent? (3) What were the rates of thinning during deglaciation? New constraints on the timing and geometry of WAIS deglaciation since the LGM will help determine Antarctic ice sheet contributions to global sea level rise since the late Pleistocene, and in particular whether this region of WAIS contributed to the period of rapid sea level rise referred to as Meltwater Pulse 1A (20 meters of global sea level rise in less than 500 years at 14.6 kya). We will present preliminary ages that address each of the three main issues associated with the last deglaciation. The chronology from this study will provide novel dates for this region due to its focus on large granite erratic boulders and the use of 10Be in its exposure ages.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFMPP13B1890B
- Keywords:
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- 0726 CRYOSPHERE Ice sheets;
- 0728 CRYOSPHERE Ice shelves;
- 1150 GEOCHRONOLOGY Cosmogenic-nuclide exposure dating