GEOMORPHIC FEATURES ASSOCIATED WITH PALEO-ICE STREAMS ON THE WEST ANTARCTIC CONTINENTAL SHELF

Detailed marine geophysical (seismic and multibeam) surveys were conducted on the West Antarctic continental shelf, from the Ross Sea to the Antarctic Peninsula, focusing on large glacial troughs where ice streams are believed to have been located during the last glacial maximum. Most of these troughs cut into crystalline bedrock on the inner shelf and offlapping sedimentary strata on the outer shelf. Thus, the influence of bedrock geology on ice stream behavior is assessed. An offshore transition in geomorphic features from grooves and striations (crystalline bedrock) to highly attenuated drumlins (thin sediment cover) to mega-scale glacial lineations (thick sedimentary strata) typifies the troughs. These features indicate accelerating ice flow across the deformable sedimentary bed. Mega-scale glacial lineations are believed to indicate ice flowing over a deforming bed and are the most common bedform associated with a sedimentary bed. Recently acquired data from the Antarctic Peninsula provide superb examples of the subglacial meltwater plumbing system that supplied the water to these deforming beds.