GLACIOMARINE ENVIRONMENTS IN CANADA - AN OVERVIEW

The present understanding of Canada's glaciomarine environments owes m uch to the remarkable role played by the scientists of the Geological Survey of Canada. Their efforts have led to the review and partial rev ision 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 (rathe r than with floating ice shelves); (3) ice-loaded glaciomarine sedimen ts are sometimes indistinguishable from deposits of till. A proposed s tratigraphic framework for Canadian glaciogenic sequences can be quant ified, allowing insights into ice sheet dynamics. For instance, the ar ctic margin of the Wisconsinan ice complex appears to have generated c omparatively 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 Pa cific counterpart. This is contrary to the present postglacial sedimen t yields discharged onto each margin. Glaciogenic sedimentation rates are shown to vary with the distance from a sediment source and the del ivery rate of sediment. Glaciogenic accumulation rates are dependent o n basin history and basin shape. Numerical examples include (1) the de termination of accumulation rates from carbon stratigraphy; (2) the ev aluation 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.