Additional Participants

Graduate Student

Nathan Gardner

Undergraduate Student

Colby Smith
Peter Marcotte
Alex Roy

Organizational Partners

Carlo Baroni, University of Pisa
Italian Antarctic Program
Rus Hoelzel, University of Durham
John Wehmiller, University of Delaware College of Marine Studies
Gideon Henderson, University of Oxford

Other Collaborators or Contacts

David Lambert of Massey U.
Michael Bryden (retired, U. Sydney)
Burney LeBeouf (Santa Cruz)
The British, Smithsonian, and Canterbury Museums
Paul Koch, (Santa Cruz)
Austin Hendy (Cincinnatti) identified the Cape Ross shells

Project Period

September 1, 2000-August 31, 2004

Level of Access

Open-Access Report

Grant Number

9909104

Submission Date

8-4-2004

Abstract

This award provides support for three years for a project to develop a radiocarbon chronology for recession of grounded ice from the northwestern Ross Sea Embayment (northern Scott Coast) since the Last Glacial Maximum (LGM). A key unresolved question in Antarctic glaciology concerns the stability of the marine-based West Antarctic ice sheet (WAIS). One way to gain insight into present and future stability is to examine its past behavior. In particular, the timing of deglaciation from the LGM position on the continental shelf is critical for isolating the mechanisms (sea level, climate, ocean temperature, and internal dynamics) that control WAIS dynamics. The northern Scott Coast was likely the first area to become free of grounded ice and hence is critical for isolating triggering mechanisms. Initial retreat from the Ross Sea Embayment was thought to have begun as early as 17,000 years ago; corresponding to the rise in sea level see in the Barbados coral record. In contrast, recent glacial geologic mapping and relative sea-level work from the southern Scott Coast suggests that deglaciation of the Ross Sea Embayment was a Holocene event, with southward grounding-line migration past Ross Island shortly before 6500 14C yr. B.P. This chronology suggests that rising sea level could not have driven grounding-line retreat to the Siple Coast, because deglacial sea-level rise essentially was accomplished by mid-Holocene. One deficiency in the southern Scott Coast work is that it cannot differentiate among the possible triggering mechanisms that initiated retreat because it is 450 km from the LGM grounding-line position. In this project, relative sea level (RSL) curves will be constructed on a transect along the northern Scott Coast from accelerator mass spectrometer 14C dates of seal skin and shells within raised beaches. These curves will provide information concerning the timing of the uploading of grounded ice from the northwestern Ross Sea Embayment. This study should help to evaluate those factors which could have triggered deglaciation and hence controlled the extent of the West Antarctic ice sheet (WAIS).

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