FROM LATE TERTIARY FLUVIAL LANDSCAPE TO PRESENT: A GENERAL THEORY ON WARM-BASED AND COLD-BASED GLACIATED TERRAINS SEDIMENTOLOGY AND GEOMORPHOLOGY IN THE NORTHEASTERN CANADIAN SHIELD

From the first descriptions of cold-based glacial erosion terrains of Bird, Sugden, Dyke and Dredge, to the present knowledge stemming from cosmogenic analyses (mainly on eastern Baffin Island, cf. papers by Miller, Refsnider, Briner, Gosse, etc.), many studies have focussed on the variable glacial erosion zones in the northeastern Canadian Shield plateaus. From the interpretation of new, detailed cold-based and warm-based (including ice streams) terrains field work observations, and geochemical, mineralogical and isotopic (cosmogenic) analyses on Boothia Peninsula, Melville Peninsula, Northern Kivalliq and Southeastern Baffin Island, this presentation will attempt to theorize on the interactions between the various geomorphological processes at play in the sector, and their effect on the erosion of the preglacial plateaus. The main processes are the glacial erosion and transport, the glaciofluvial (including subglacial, ice-marginal, supraglacial and glaciolacustrine) erosion and transport, and the in–situ processes (chemical weathering [preglacial, interglacial and post-glacial], colluvial, periglacial, etc.). A ternary diagram summarize the geomorphological results obtained at this stage of the multi-year project. This research project started in 2007 with the study of ice streams on Boothia Peninsula, and 2009 on Melville Peninsula with the detailed GIS analysis of cold-based glacial erosion index and the description of 2D (dispersal features) and 3D (topographic features) macroforms in the vicinity of cold-based zones. Recent results obtained on Melville Peninsula in collaboration with J. Gosse (U. Dalhousie), indicates the presence of relict, weathered terrains in the cold-based zone supported by beryllium 10 concentration exceeding the postglacial accumulation of this isotope. Detailed mapping of ice streams and cold-based zones on Southeastern Baffin Island (2011-2015) will also be presented, as well as TCN and mineralogy data from Hall Peninsula (with M. Ross, U. of Waterloo, and M. Allard, U. Laval). New detailed mapping results from northern Boothia Peninsula, the Keewatin plateau (with Isabelle McMartin, GSC) and Southampton Island (with Martin Ross and Sam Kelley, U. of Waterloo) are awaited for 2018. New fieldwork is planned for 2018 on Somerset Island and Northwest Baffin Island.