Glaciomarine environments in Canada: an overview

Abstract

The present understanding of Canada's glaciomarine environments owes much to the remarkable role played by the scientists of the Geological Survey of Canada. Their efforts have led to the review and partial revision of three scientific paradigms: (1) There is a mechanical rather than a climatic control of the collapse of a tidewater ice sheet; (2) ice sheets were mostly grounded on Canada's continental shelves (rather than with floating ice shelves); (3) ice-loaded glaciomarine sediments are sometimes indistinguishable from deposits of till. A proposed stratigraphic framework for Canadian glaciogenic sequences can be quantified, allowing insights into ice sheet dynamics. For instance, the arctic margin of the Wisconsinan ice complex appears to have generated comparatively little meltwater, ice margin retreat being principally by iceberg calving. Surprisingly, the Atlantic margin of the Wisconsinan ice complex appears to have transported larger quantities than its Pacific counterpart. This is contrary to the present postglacial sediment yields discharged onto each margin. Glaciogenic sedimentation rates are shown to vary with the distance from a sediment source and the delivery rate of sediment. Glaciogenic accumulation rates are dependent on basin history and basin shape. Numerical examples include (1) the determination of accumulation rates from carbon stratigraphy; (2) the evaluation of the flux of sediment from a fjord to the open shelf during the retreat phase of an ice sheet; and (3) the application of a basin fill model to predict the styles of sedimentation within a fjord.