CGRG Bibliography of Canadian Geomorphology
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Author : Gray, J.; Gosse, J.; and Marquette, G.
Date : 2002.
Title : Autonomous centres of ice dispersal in the Torngat Mountains and Gaspésie : implications for Laurentide ice sheet modelling during the LGM.
Publication : Atlantic Canada Glacier Ice Dynamics Workshop, May 22-24, 2002. Dalhousie University, Halifax, Nova Scotia.
Issue :
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Abstract
Modelling of Laurentide ice sheet volumes has generally been based on the outermost limits of a single or multi-domed continental scale ice sheet, along with overall patterns of glacial unloading. Field evidence from the Torngat Mountains and Gaspésie, highland areas on the eastern and southeastern periphery of the Québec-Labrador sector of the LIS, suggest that during the LGM, the distribution of coalescing ice dispersal centres is more complex than the models have hitherto recognised. In the case of the Central Torngat Mountains, striae, fluting forms, and the spatial pattern of distribution of glacial erratics, as well as areal trends in the distribution of felsenmeer limits and lateral moraines, indicate ice flows both to Ungava Bay and the Labrador Sea from locally coalescing plateau ice-fields and cirque glaciers, of probably limited thickness. This evidence is indirectly supported by glacio-isostatic uplift patterns from both flanks of the Northern Labrador Peninsula. 10Be dates and one 26Al date indicate that the felsenmeer covered surfaces pre-date the LGM. The felsenmeer limits are postulated to represent the level of frozen-based ice, and this should be a useful parameter for modelling the maximum thickness of the local ice sheets. Only during a late deglaciation phase, as local glaciers retreated, was ice from Ungava Bay able to penetrate into the Torngat through valleys, damming up several glacial lakes in the process. For Gaspésie similar field evidence is adduced for radial dispersal of local and relatively thin highland ice sheets northwards eastwards and southwards respectively into the Gulf of St Lawrence and the Baie de Chaleurs. In this case the LIS from Québec-Labrador most probably bifurcated along the Laurentian Channel to the east and through the Matapedia Valley to the west of the Gaspé highlands.
Bibliography of Canadian Geomorphology