SEISMIC MORPHOLOGY AND DISTRIBUTION OF INFERRED GLACIOMARINE DEPOSITS ALONG THE EAST ANTARCTIC CONTINENTAL MARGIN, 20°E-60°E

Abstract

Seismic-reflection profiles from the continental rise and abyssal plain along a nearly 2000-km long stretch of the East Antarctic margin have been studied, including the Cosmonaut Sea basin and adjacent parts of the Riiser-Larsen Sea to the west and the Cooperation Sea to the east. The recognition of glaciomarine deposits is based on their correlative basal reflector and acoustic characteristics. The lateral distribution of seismostratigraphic sediment thickness, internal architecture of reflectors and seafloor morphology reveal a number of deep-water depocentres with large paleo-channels. These main depocentres correspond to the coastal outlets of present-day ice streams and hence indicate longer-term stabilities in the ice-stream positions during the Neogene advance and retreat phases of the Antarctic Ice Sheet. Scattered paleo-channels and subordinate depocentres in the Cosmonaut Sea suggest that some of the ice streams might occasionally change their position or that also other ice streams were episodically involved during earlier glacial maxima.