Marine geological and geotechnical investigations in Wellington, Byam Martin, Austin, and adjacent channels, Canadian Arctic Archipelago

Abstract

Marine geological and geophysical investigations were carried out in Wellington Channel, Byam Martin and Austin channels, and in eastern Barrow Strait-western Lancaster Sound from CSS HUDSON in i986. These investigations provided information on the distribution, thickness, composition, depositional environments, geotechnical properties, and regional geological setting of the surficial sediments, and on the structure of the near surface bedrock. The data indicate the widespread occurrence of sediments of apparent glacial origin (glacial drift) which overlie variably dipping sedimentary bedrock, and which are in turn locally overlain by up to a few metres of acoustically stratified and acoustically transparent sediments, interpreted to represent glaciomarine and postglacial sediments respectively. The drift unit locally forms constructional features interpreted to be moraines, and in places contains multiple sequences. Surficial sediment thicknesses in Wellington Channel commonly are less than JO m but locally reach 25 m, are somewhat greater in Byam Martin and Austin channels (up to 50 m), and are generally greater in eastern Barrow Strait, where they locally reach iOO m. Geotechnical, foraminiferal and textural data show consistent correlations with one another and with the acoustic stratigraphic units. The postglacial sediments have a high water content, low bulk density, and low shear strength; the converse applies to the glaciomarine and glacial drift sediments. Foraminifera are relatively diverse in the postglacial sediments, less diverse in the glaciomarine sediments, and are absent in the glacial drift. Magnetic susceptibility data suggest that most of the sediments probably were derived from Paleozoic rocks of the Arctic islands, but that glacial drift in northern Prince Regent inlet and glaciomarine sediments in eastern Barrow Strait-western Lancaster Sound may have been derived partly from Precambrian rocks bordering part of the Gulf of Boothia, south of Prince Regent Inlet. Some seafloor sediments, particularly the glacial drift, have been modified by ice scour.