Till Provenance Across Glacial Landscapes of the Laurentide Ice Sheet in Central Nunavut and Eastern Northwest TerritoriesTuesday, November 19, 2019 - 3:00pm to 3:20pm Theatre One
Our research documents glacial dispersal within the interior region of the Keewatin Sector of the Laurentide Ice Sheet, mainland Northwest Territories and Nunavut, to better understand till provenance and refine regional glacial transport models to improve surface exploration methods in the Rae and Hearne provinces of the Canadian Shield. The objectives of this study are to: 1) characterize the regional till composition (provenance) across major geological and glaciological features and 2) evaluate glacial transport in areas of complex ice flow dynamics and changing basal ice thermal regimes.
Selected ~100-km long transects incorporate previous and new surface till composition datasets (clast lithology, texture and matrix geochemistry/mineralogy) from samples collected at a regional scale (~10-km spacing) across various glacial terrains such as paleo-ice stream corridors, major moraine systems, relict landscapes and ice divides. Specifically, the study includes transects crossing former ice front positions marked by the MacAlpine and the Chantrey moraines, the onset zone, trunk and terminus of major ice streams (e.g., Dubawnt Lake, Maguse Lake and Rae Isthmus ice streams), the Keewatin Ice Divide, relict cold- to intermediate-based terrains, and areas impacted by patchy sustained normal vs. fast flowing ice (i.e., sticky spots). The distribution of distinct bedrock lithologies (e.g., Dubawnt Supergroup) as source indicators combined with multivariate analysis of the geochemical composition of the till matrix will be used to evaluate the distal, proximal and possibly palimpsest and/or inherited components of glacial transport history, and document its relation with the type of glacial landscape. Overall, these results will have implications for future surface mineral exploration at a regional scale in northern Canada. This work is part of the Rae Synthesis of Glacial History and Dynamics Activity under the GEM-2 Program, and is a collaboration between the Geological Survey of Canada, the Northwest Territories Geological Survey and the Canada-Nunavut Geoscience Office.