The subglacial record of northern Hudson Bay: insights into the Hudson Strait Ice Stream catchment

摘要

In this paper, we present new insights into the glacial dynamics and potential configuration of the Hudson Strait Ice Stream catchment in the northern Hudson Bay-western Hudson Strait region. Our reconstruction is based on new field observations and till compositional data from Southampton Island, remote sensing imagery and multibeam bathymetric data from the Hudson Bay sea floor, as well as on a re-examination of previously published data from this vast region. Our findings suggest that, during the late Quaternary, the HSIS catchment consisted of a number of ice-stream tributaries feeding a curvilinear trunk that potentially extended into western Hudson Bay. In contrast to previous interpretations, the occurrence of fluted bedrock hills, over-deepened basins, Dubawnt erratics and carbonaceous till on the islands at the head of Hudson Strait is taken to imply that cold-based conditions did not prevail on these islands. The upland area of Southampton Island and the surrounding channels played an important role in controlling the location of the main tributaries, with the higher central terrain forming a large inter-ice-stream zone lacking carbonate detritus. Coats Island contains abundant evidence of vigorous ice flow, such as mega-scale glacial lineations (MSGLs). MSGLs also occur on the sea floor southwest of Coats Island but the sea-floor imprint is highly discontinuous. Observations on the western Hudson Bay mainland show evidence of southeastward fast ice flow that is spatially consistent with the Dubawnt dispersal train. Despite the geomorphological discontinuities, this may indicate that the HSIS onset zone extended far inside the Laurentide Ice Sheet and across contrasting geological domains.