BLANKETING SNOW AND ICE - CONSTRAINTS ON RADIOCARBON DATING DEGLACIATION IN EAST ANTARCTIC OASES

Radiocarbon dating of marine, lacustrine or terrestrial biogenic depos its is the main technique used to determine when deglaciation of the e ases of East Antarctica occurred. However, at many of the eases of Eas t Antarctica, including the Schirmacher Oasis, Stillwell Hills, Amery Oasis, Larsemann Hills, Taylor Islands and Grearson Oasis, snow and ic e presently forms extensive blankets that fills valleys and some lake basins, covers perennial lake ice and in places overwhelms local topog raphy to form ice domes up to hundreds of square kilometres in area. F ield observations from Larsemann Hills and Taylor Islands suggest that under these conditions, terrestrial and lacustrine biogenic sedimenta tion is neither widespread nor abundant. If similar conditions prevail ed in and around the eases immediately following retreat of the ice sh eet, then a lengthy hiatus might exist between deglaciation and the on set of widespread or abundant biogenic sedimentation. As a result, rad iocarbon dating might be a clumsy tool with which to reconstruct degla ciation history, and independent dating methods that record emergence of the hilltops from the continental ice must be employed as well.