Glacial geomorphology and cosmogenic 10Be and 26Al exposure ages in the northern Dufek Massif, Weddell Sea embayment, Antarctica

We studied the glacial geomorphology and geochronology of two ice-free valleys in the Dufek
Massif (Antarctic Specially Protected Area 119) providing new constraints on past ice sheet thickness in the
Weddell Sea embayment. 10Be and 26Al cosmogenic surface exposure dating provided chronological
control. Seven glacial stages are proposed. These include an alpine glaciation, with subsequent (mid-
Miocene?) over-riding by a warm-based ice sheet. Subsequent advances are marked by a series of minor
drift deposits at 760m altitude at .1 Ma, followed by at least two later ice sheet advances that are
characterized by extensive drift sheet deposition. An advance of plateau ice field outlet glaciers from the
south postdated these drift sheets. The most recent advance involved the cold-based expansion of the ice sheet
from the north at the Last Glacial Maximum, or earlier, which deposited a series of bouldery moraines during
its retreat. This suggests at most a relatively modest expansion of the ice sheet and outlet glaciers dominated
by a lateral ice expansion of just 2–3 km and maintaining a thickness similar to that of the northern ice sheet
front. These observations are consistent with other reports of modest ice sheet thickening around the Weddell
Sea embayment during the Last Glacial Maximum.