Friday, 31 August 2007
5.PS-132
Contrasting sub-ice shelf, sub glacial and glacial marine deposition: implications for ice shelf stability
Lauren W.E. Boyd1, Louis R. Bartek III1, Bruce P. Luyendyk2, and Douglas S. Wilson2. (1) Department of Geological Sciences, University of North Carolina-Chapel Hill, CB#3315, Chapel Hill, NC 27599-3315, (2) Dept Earth Science, UCSB, Santa Barbara, CA 93106
Data from cores collected from sites that were beneath the Ross Ice Shelf until 2000 and 2002 indicate that sub-ice shelf lithofacies are distinguishable from sub-glacial and glacial marine facies. Glacial marine sediment is characterized by diatom-rich, low-density, olive-green, sandy-muds, whereas sub-ice shelf sediment is defined by a lack of diatoms and muds that are enriched in silt and fine sand. Sub-glacial sediment is composed of diatom-poor, high density, coarse grained sandy-mud, rich in fine to coarse sized pebbles. Repetitive, fining-up packages, composed of fine-sand/silty-mud (distal sub ice-shelf deposits), grading into coarse pebbly-mud (sub ice-shelf proximal to the grounding line), suggest cyclicity in the movement of the grounding line over the last 11,000 yrs in the eastern Ross Sea . This research may facilitate a new understanding of ice-shelf dynamics, and possibly refine the current models for the Ross Ice Shelf’s recent glacial history.