The LGM Ice Sheet Reconstruction for the Antarctic Peninsula: Can the Data Satisfy Geophysical Models?

John B. Anderson, Department of Earth Science, Rice University
Houston, Texas, 77251-1892

The configuration of the Antarctic Ice Sheet during the LGM and its contribution to the post LGM sea-level rise have been modeled by several investigators, with widely different results (e.g. Denton et al., 1991; Huybrechts, 1990; Tushingham and Peltier, 1991; Nakada et al., 2000). These models differ considerably with regard the distribution of ice on the continent and the range of sea-level contributions from melting of the ice sheet. The principle difference between the models is where ice occurs on the continent. Recent models (ANT5 and ANT6) by Nakada and others (2000) place significantly more ice on the Antarctic Peninsula region than exists in previous models.

Marine geological data acquired from the continental shelf of the Antarctic Peninsula region provide direct evidence that the Antarctic Peninsula Ice Cap expanded onto the continental shelf during the LGM, but the actual extent of the grounded ice cap and the timing of its retreat from the shelf remains problematic. Along the southern portion of the Peninsula, the ice sheet is known to have grounded in Marguerite Bay and on the inner shelf (Pope and Anderson, 1992).No conclusive evidence for grounding on the outer shelf exists. In the northern sector of the Peninsula, grounding zone ridges, tills, flutes and mega-scale glacial lineations provide strong evidence that the ice cap was grounded on the outer continental shelf (Pudsey et al., 1994; Anderson, 1999; Canals et al., 2000). Sub-ice shelf deposits overly till on the shelf and indicate that an extensive fringing ice shelf covered the shelf after the ice sheet retreated (Pope and Anderson, 1992).

Radiocarbon dates from glacial-marine sediment above the till indicate that the ice sheet retreated from the shelf prior to 14,000 years ago (radiocarbon years) and that open marine conditions have existed on the shelf throughout the Holocene (Domack et al., 2001).

References Cited

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