Slides and debris flows on the high-latitude continental slopes of Baffin Bay

The eastern continental margin of Baffin Island around Ocean Drilling Program (ODP) Site 645 was surveyed by using single-channel airgun, high-resolution boomer systems and piston cores. The data show that much of the upper slope between the 300 and 1200 m isobaths is erosional. Major sliding and rotational slumping has removed several hundred metres of sediment from the upper slope, giving the sea bed a steplike morphology. From 1200 m to the 2300 m isobath, the slope is constructional and is characterized by abundant acoustically transparent lenses, some of which are traced upslope into acoustically transparent to internally deformed wedge-shaped bodies. These lenses are interpreted to be debris-flow deposits and their abudnance in the lower slope indicates frequent upper slope failures. The wedge-shaped bodies are much less common and are interpreted to be larger slides and/or slumps. Near the base of the slope, fields of diapiric structures pierce the acoustically well stratified section and locally produce small mounds on the sea floor. On the basis of correlation with ODP Site 645, they are interpreted as mud diapirs. The combined data show that the lower slope of Baffin Island is constructed predominantly of shingled lenses of debris-flow deposits and rotated slump blocks that originated from major erosion of the upper slope.