SUBMARINE DEBRIS FLOWS AND CONTINENTAL-SLOPE EVOLUTION IN FRONT OF QUATERNARY ICE SHEETS, BAFFIN-BAY, CANADIAN ARCTIC

Baffin Bay is a semi-enclosed extension of the Labrador Sea in the Can adian Arctic. The upper Pliocene and Quaternary successions beneath th e continental slope contain important slumps and debris-flow deposits. New high-resolution single-channel seismic data have been acquired fr om a 500 to 600-m-deep transverse trough that indents the shelf in an area where glacial outflow was focused during the Pliocene and Pleisto cene. Major shelf-edge progradation occurred both inside and on the fl anks of the transverse trough. In the lower slope, several large debri s flows carried proglacial deposits into the deep basin. The largest o f these debris flows dramatically reshaped the sea floor by reducing b ottom slopes both by proximal erosion and distal thickening of the deb ris-flow deposit. Subsequently, the lower slope was starved of terrige nous input, and the upper slope was steepened by accumulation of basin ward thinning wedges of mass flow deposits. The processes of emplaceme nt of large debris flows, slope reshaping, and out-of-phase accumulati on identified in upper and lower slope areas of Baffin Bay are relevan t to the interpretation of other line-source margins affected by major sea level falls or changes in sediment influx, including siliciclasti c slope aprons and carbonate platform margins.