Tuesday, 28 August 2007 - 10:50 AM
2.A.A-3

A glacial to interglacial sediment model and retreat history for the Ross Ice (Sheet) Shelf in Western Ross Sea since the Last Glacial Maximum

R. M. McKay1, G. B. Dunbar1, T. R. Naish1, Peter Barrett2, L. Carter1, and M. A. Harper1. (1) Antarctic Research Centre, Victoria University of Wellington, Wellington, New Zealand, (2) Antarctic Research Centre, Victoria University of Wellington, Wellington, New Zealand

Sediment cores from beneath the McMurdo Ice Shelf and north of Ross Island, display a succession of facies that document the retreat of the grounded Ross Ice Sheet during the LGM to the present-day open-marine and ice-shelf environments. The succession comprises in ascending stratigraphic order: (1) clast-rich muddy diamict interpreted as basal glacial debris melt-out proximal to a retreating grounding zone; (2) sparsely-fossiliferous, non-bioturbated mud lacking lonestones, interpreted as a sub-ice shelf facies; and (3) diatom-bearing  mud and diatom ooze with IRD indicative of open water conditions. Our chronology implies lift-off of grounded ice in the 900 m-deep marine basins surrounding Ross Island by ~10,100 14C yr BP. However, an ice shelf remained north of Ross Island until ~8,900 14C yr BP. About that time, the calving line was pinned to Ross Island while the grounding line hundreds of kilomteres to the south, marked the present-day ice shelf mode.

[Manuscript]

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