Iceberg Scour Investigations and Sedimentology of the Southeast Baffin Island Continental Shelf

Abstract

High-resolution sidescan imagery of the southeast Baffin Island continental margin illustrates a typical high-latitude shelf, extensively and deeply scoured by the southward drift of icebergs. Evidence for iceberg scouring on the shallower inner shelf is not clearly manifested, reflecting the very thin sediment cover overlying the bedrock. On the deeper mid- and outer shelves, the iceberg scours are generally much more clearly defined. These deeper water scours, which are kilometres long, up to 90 m wide and 4.4 m deep, are not a recent occurrence. Instead they are relict and probably predate the Holocene/latest Pleistocene, when sea levels were relatively much lower. Two depth-related surficial sedimentary environments (an inner shelf and mid- and outer shelf environment) are recognized in the survey area. A thin (few centimetres thick) covering of coarse sand and/or gravel with negligible amounts of silt and clay dominate the inner shelf down to about the 220 m contour, and because of this sparse covering, the underlying bedrock is very often exposed. The mid- and outer shelves, which have a sediment cover up to 7 m thick, are texturally very variable. This variable texture reflects the effects of scouring iceberg keels in dislodging sediment and the subsequent displacement and redistribution of sediment. Underwater photographs of current generated bedforms suggest further bottom current redistribution of displaced scoured sediments and concurrent active sediment transport on the outer continental shelf.

Key words: Baffin Island continental shelf, marine geology, sedimentology, iceberg scours