LARGE-SCALE MORPHOLOGY OF ARCTIC CONTINENTAL SLOPES: THE INFLUENCE OF SEDIMENT DELIVERY ON SLOPE FORM

Abstract

The continental slopes of the pan-Arctic region exhibit a range of morphological expression inherently related to different styles of glaciation and sediment delivery to the slope. This study examines the basic associations between glacial processes and morphology at the regional scale. A Geographical Information System (GIS) is applied to a new bathymetric grid of the Arctic Ocean in order to compare the slope angle and sea-floor roughness of 70% of Arctic continental slopes. We also subdivide the circum-Arctic continental slope with respect to parameters likely to influence sediment delivery to the slope. These include proximity to Late Quaternary glacial advance, convergent versus divergent ice termini, and the presence or absence of glacial shelf troughs. Comparison shows that those continental slopes that experience higher sediment input dip more gently than slopes with less sediment input. On glaciated margins where the expanding ice sheet would have produced convergent (faster) ice flow, continental slopes have mean slopes of 1.3degrees on average. This is in contrast with margins that have experienced divergent (slower) ice flow which tend to have steeper slopes (mean of 2.2degrees). There is a direct relationship between morphological variability among trough-mouth fans and the width of the adjacent continental shelf (i.e. size of the trough). Longer troughs give rise to slope fans with a more gentle profile geometry. This finding, though simple, suggests a dependency of slope morphology on sediment input to the slope through basal ice sheet erosion. Published values for sediment discharge to several trough mouth fans support this concept. A model is proposed for fan development that relates a fan's geomorphic state to its stage of stratigraphic development.