International studies of ice sheet and bedrock

Abstract

The main Antarctic ice sheet is so vast that large-scale international programmes are necessary for an adequate study of its dynamics, thermodynamics and past history. Radio echo sounding methods are providing reconnaissance mapping of the ice sheet on a continental scale. The soundings also yield significant information on the internal deformation of the ice sheet, on the flow of ice shelves and the nature of the bottom surface of the ice. This information is being used to amplify and extrapolate detailed results from other groups who are studying the mass balance, ice movement, and past history by deep drilling; it is also of value in isolating critical sites for future studies. Reconnaissance mapping has now shown the presence of sub-ice lakes larger than those reported in 1973. Studies of radio wave reflexions from internal layers which are believed to be former depositional surfaces, have shown that the conformity between these layers and the bedrock relief decreases as ice movement increases. Statistical analyses of bedrock relief and radio wave reflexion parameters are being used to delimit major geological provinces beneath the ice and investigate the structural and lithological transition between the Transantarctic Mountains and East Antarctica. Such studies have recently indicated the presence and structure of two large intracratonic sedimentary basins in eastern Antarctica.