Collaborative Research: West Antarctic Ice Sheet Stability: The Glacial Geologic Record from the Ohio Range of the Horlick Mountains in the Bottleneck

• Main Author: Borns, Harold W., Jr.
• Format: Text
• Language: unknown
• Published: DigitalCommons@UMaine 2008
• Subjects: West Antarctic ice sheet; WAIS; Ohio Range; Mercer Ice Stream; Transantarctic Mountains; Glaciology; Antarctic; Ross Sea; West Antarctic Ice Sheet; McMurdo Sound; Mercer; Narrow Passage; Horlick Mountains; Antarc*; Ice Sheet; Ice Stream A
• Online Access: https://digitalcommons.library.umaine.edu/orsp_reports/242; https://digitalcommons.library.umaine.edu/cgi/viewcontent.cgi?article=1248&context=orsp_reports

This award supports a project to document former high stands and assess the stability of the West Antarctic ice sheet (WAIS) at the Ohio Range near the head of Mercer Ice Stream (formerly Ice Stream A). The field location is situated in the "Bottleneck", a unique, relatively narrow passage in the Transantarctic Mountains connecting the West and East Antarctic ice sheets. The location lies near the ice divide and is thus well situated to determine past interior ice elevation. The research will involve geologic mapping of glacial deposits and erosion features combined with cosmogenic surface exposure dating on the Ohio Range nunataks to determine the chronology of past higher ice sheet levels and local glacier fluctuations. Exposure ages of fresh glacial erratics, up to 60 m above the present ice level will be used to constrain the timing of the last high stand and subsequent draw down of the WAIS in this sector. Exposure ages of debris bands on the ice sheet surface will constrain the duration of continuous ice cover near the present elevation. A complimentary local proxy climate record will also be obtained from a chronology of the local glacier moraines. Data obtained from the proposed research will contribute to the development of time-dependent, non-equilibrium models of the WAIS, at and since the last glacial maximum 20,000 years ago, a major objective of the West Antarctic Ice Sheet Initiative. Age control on ice sheet elevation from this key location, near the head of the Mercer Ice Stream, will complete chronologic coverage extending from the ice age terminus in the Ross Sea, through McMurdo Sound and the southern Transantarctic Mountains, to the onset area near the ice divide. In addition, the glacial geologic record in the Bottleneck will reflect the history of the interaction of WAIS and EAIS, which could be used to test hypotheses of Pleistocene collapse of the WAIS. The future behavior of the WAIS is of significant interest to society because of its linkage to sea level. Melting of Antarctic ice ...