Reconstruction of the West Antarctic Ice Sheet in Pine Island Bay during the last glacial maximum and its subsequent retreat history

Marine-geological and -geophysical studies were conducted to determine the Late Quaternary glacial history of the West Antarctic Ice Sheet in Pine Island Bay, Antarctica. The data set includes sea-floor imagery in the form of multibeam swath bathymetry and deep-tow side-scan sonar surveys. Distribution of sedimentary deposits and basal surface conditions are revealed through intermediate-resolution seismic data and chirp (3.5 kHz) sub-bottom profiles. Sedimentary deposits were sampled with piston cores, and calcareous material was dated using AMS radiocarbon techniques. Results from the study indicate the ice sheet was grounded on the outer shelf during its maximum extent sometime in the past. Thick ice, flowing slowly and resting on crystalline bedrock, was influenced by significant amounts of subglacial meltwater on the inner shelf. Thinner, but more rapidly flowing, ice characterized the seaward extent of the ice sheet, which was grounded on a sedimentary substrate. Deglaciation occurred in two phases, beginning soon after the last glacial maximum. The outer-most extension of the ice sheet retreated gradually, pausing on a bathymetric high on the middle shelf by similar to 16,000 C-14 years ago. Between similar to 16,000 and 12,000 C-14 years ago, ice-sheet retreat resumed, and may have proceeded rapidly to reach a present-day position by similar to 10,000 C-14 years ago. (C) 2002 Elsevier Science Ltd. All rights reserved.