Chronology of the West Antarctic Ice Sheet: New Evidence from Marie Byrd Land Nunataks

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0087709Kurz This award supports a project for a detailed laboratory-based study of glacial moraine boulders collected on the flank of Mt. Waesche, a nunatak in the Executive Committee Range, Marie Byrd Land, West Antarctica. Preliminary work on these samples resulted in measurement of past ice sheet elevations in interior West Antarctica. Funds are requested here to measure exposure ages in the remaining samples from the moraine and adjacent volcanic bedrock. The goal is to use a combination of field observations, surface exposure dating (Helium-3, Neon-21 and Chlorine-36) and Argon-40/Argon-39 dating to constrain past elevations of the West Antarctic ice sheet (WAIS). The initial study demonstrated that higher past ice levels are recorded by moraines, composed of volcanic debris left behind by receding ice, and that Helium-3 and Chlorine-36 surface exposure dating can be used to constrain the timing of past ice high stands. It is expected that these analyses will refine the initial results pertaining to the last deglaciation and provide a unique record of earlier ice sheet elevations. The primary long-term objective is to provide chronological and elevation data of the paleoglaciology of the interior of the WAIS prior to 10 kA. The unique record of surface ice elevations at Mt. Waesche provides key constraints on the behavior of the ice sheet and its response to climate and sea level change. This information will contribute strongly to determining why the WAIS behaved as it did during the last deglaciation and the previous interglacial, and will help efforts to predict how it will change in the future.