Provenance and depositional facies of surficial sediments in Hudson Bay, a glaciated epeiric sea.

Abstract

A model for Wisconsinan glaciation and deglaciation of Hudson Bay is proposed based on depositional facies of the surficial sediments. These facies, defined on the basis of texture, composition, and acoustic character, indicate that sediment distribution is controlled primarily by Late Wisconsin glaciation. Post-glacial sedimentation is restricted to the shallow marine environment (100m deep) and involves reworking of glacially-derived sediments by rivers and/or marine currents. Deposition due to sea-ice rafting is minor. Within the glacigenic sediments, dispersal trends of distinctive lithologies and mineralogies (derived from sources adjacent to and underlying the bay) indicate that (1) western Hudson Bay was glaciated by ice flow eastward from a centre in the District of Keewatin, and (2) the eastern and southern bay was glaciated by ice flow westward from a dispersal centre in Nouveau Quebec. Seafloor geomorphic features and sediment composition suggest that deglaciation was focused at the confluence between these two ice sheets, possibly through ice streaming and calving bay formation. Eastward and southward dispersal of sediment derived from sources within the bay suggest a residual ice mass remained centered over Hudson Bay following glacial maximum. The deglaciation model invokes stabilization of the ice margin in the north, extension of a calving bay in Hudson Strait into west-central Hudson Bay, northward drainage of proglacial lakes along major bathymetric depressions, and, finally, rapid collapse of the ice sheet.