Late Quaternary Dynamics of the Labrador/Foxe Sectors of theLaurentide Ice Sheet and Ice-Sheet/Ocean Interaction in the North Atlantic

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The demonstration of a major advance from a Labradorean dispersal center flowing essentially at right angles to regional topographic features, and that overtopped Loks Land despite an unconstrained margin facing the open ocean to the SE, provides strong evidence that the flux of ice during this advance must have been great. The cross-sectional area for that portion of the ice facing the Labrador Sea is ca. 300 km2. Assuming a velocity between that of Jacobshavn Glacier, an outlet glacier draining the Greenland Ice Sheet (8 km a-1), and the Ross Ice Shelf, Antarctica (1 km a-1) yields an annual flux of 300 to 2400 km3 a-1. This is about the same fresh-water flux entering the North Atlantic when the St Lawrence outlet was opened by the retreating Laurentide Ice Sheet 11,000 years ago (30,000 m3 sec-1 or 1000 km3 a-1; Teller, 1988). Recognizing the importance of ice-sheet/ocean interactions in the global climate system, we are proposing a research campaign to include a new field effort to define more precisely the spatial limits of this newly recognized advance, and the timing of its onset and retreat, and to model the ice dynamics based on the field evidence. Specifically, we intend to address five objectives: 1) Defining the maximum limits of the Labradorean advance; 2) Deciphering the interaction between the Foxe outlet glacier the flowed out Frobisher Bay and the Labradorean ice sheet backfilling the bay; 3) Determining whether all of Meta Incognita Peninsula was over-ridden by Labradorean ice; 4) Defining the temporal limits of these advances; and using the field evidence on the limits and timing of ice sheet advance and retreat as input to glaciological models to provide realistic ice limits, and ice velocities. Accurate reconstructions of the overall configuration of the Laurentide Ice Sheet and the pattern of its flow are necessary to understand the climate and general circulation during a glaciation, the response of the earth's crust to loading, and contribute to our understanding of ice dynamics.