NEW SEISMIC DATA SUPPORT CENOZOIC RIFTING IN GEORGE-VI-SOUND, ANTARCTIC PENINSULA

New multifold seismic-reflection and wide-angle reflection/refraction data across George VI Sound, Antarctic Peninsula, show the presence of graben and horst structures indicating an extensional origin. The dat a suggest that rocks of an accretionary complex and fore-are basin und erlie the Sound and are in faulted contact along its eastern boundary with volcanic and plutonic rocks of the associated Mesozoic are of wes tern Palmer Land. A cover of possible syn- and postglacial Cenozoic de posits drapes the structures. The combination of new seismic, syntheti c-aperture radar and previously acquired data suggests subduction-rela ted rifting in the Sound was segmented, with opening in the south pred ominately by normal extension whilst in the north, dextral transtensio n predominated.