Modeling Geomorphological and Cosmogenic-Nuclide Constraints on the Volume of the Quebec-Labradorean Sector of the Last Laurentide Ice Sheet

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The Principal Investigator will continue an ongoing, long-term, collaborative study of the significance of altitudinally separable differentially weathered bedrock surfaces that occur along the eastern coastal highland periphery of the Laurentide Ice Sheet (LIS). This project will focus on 1) determining the exposure and burial histories of bedrock surfaces, using terrestrial cosmogenic nuclides and geomorphic data; and 2) incorporating these data with geological evidence for ice cover and ice flow into new models for the geometry of the Quebec-Labradoran sector of the LIS. Emphasis will be placed on the most weathered terrains in regions that have focussed throughout the twentieth century in the 'nunatak controversy'.This project has three principal components: 1) obtaining chronological constraints by making measurements of 10Be and 26A1 in rock exposed to cosmic radiation; 2) interpreting chronological evidence in terms of the geological and geomorphological field evidence to address three century-old controversial questions; 3) developing a new ground-truthed geometry using a combination of forward and inverse ice sheet models that are sensitive to surface geological boundary conditions and vertical and lateral limits as pinned along the eastern margin.Results of this research will have direct implications on present and future studies of mantle rheology, will provide a mechanism to test the validity of existing and widely-used LIS ice sheet models, and will improve our interpretation of marine isotopic records. A ground-truthed model of the eastern LIS and will help our understanding of the LIS on sub-Milankovitch climate and iceberg rafting events in the north Atlantic.