ARCTIC ICE SHEETS IN CANADA: NEW PERSPECTIVES FROM A FOUR DECADE, 2000 KM TRANSECT ACROSS THE CANADIAN ARCTIC ARCHIPELAGO

During the past four decades, the extent, chronology and dynamics of the northern Laurentide and Innuitian ice sheets in the Canadian Arctic Archipelago (CAA) have been fundamentally clarified. This has been facilitated by thousands of hours of aircraft support to complete a systematic transect across the archipelago whose success has been augmented by the advent of diverse, new methodologies. It is now documented that the Laurentide and Innuitian ice sheets either approached or exceeded their all-time limit during MIS 2, advancing seaward of all coastlines onto the polar continental shelf – possibly nourished by a split jet stream and buttressed by landfast sea ice. Ongoing seafloor mapping will doubtless clarify the offshore extent and chronology of these margins. New perspectives include: the rapid and late MIS 2 buildup of both the northern Laurentide and Innuitian ice sheets; their primary ice divides and ice streams that delivered deep-draft icebergs and sediment to the Arctic Ocean and Baffin Bay; the mapping of former Antarctic-scale ice shelves both during the buildup and catastrophic breakup of land-based ice, notably in the western Arctic; and the chronology of deglaciation that includes a Younger Dryas stabilization and readvance in the western CAA followed by rapid or catastrophic, west to east regional retreat of the marine margins of both ice sheets. A pan-archipelago sea level record spanning deglaciation to modern (> 2000 ¹⁴C dates) clearly delineates zones of modern emergence and submergence that complement the ice sheet history. New observations strengthen the unresolved hypothesis that the earliest, and likely most extensive, northwest Laurentide Ice Sheet was favoured (dynamically) by its advance across what was once a contiguous Arctic landmass crossed by Late Tertiary rivers later severed by block faulting, forming the modern Arctic islands and intervening marine channels.