Northeastern Section - 53rd Annual Meeting - 2018

Paper No. 26-9
Presentation Time: 10:55 AM


BROUARD, Etienne, Department of Geography, Laval University, 2405, rue de la Terrasse, Quebec City, QC G1V 0A6, Canada and LAJEUNESSE, Patrick, Department of Geography, Université Laval & Centre for Northern Studies (CEN), Pavillon Abitibi-Price, 2405, rue de la Terrasse, Quebec city, QC G1V 0A6, Canada

A glacial landsystem approach has been used to investigate ice-sheet retreats in previously englaciated terrain in order to provide analogues for modern ice-sheet response to climate change and sea-level rise. Although some sectors of palaeo-ice sheets have been the focused of numerous landsystem studies, none has focused on the Laurentide Ice Sheet (LIS) in Arctic Canada. At its maximum, the northeastern part of the LIS reached the outer continental shelf edge in Western Baffin Bay to subsequently retreat through the coastal mountain range and fjords of northeast Baffin Island. Understanding of the former dynamics of retreat of the LIS through northeastern Baffin Island fjords can therefore provide a valuable palaeoglaciological analogue for predicting future GIS dynamics related to climate change. Here, we present swath-bathymetric data and geomorphological maps from northeastern Baffin Island fjords that reveal a variety of deglacial to postglacial landforms and we discuss their significance for glacial dynamics in fjords. Ice-flow landforms such as mega-scale glacial lineations, crag-and-tails and meltwater channels reveal the direction and behaviour sof late-Wisconsinan ice flow through the fjords. The presence of undisturbed elongated features within the fjords suggests that ice streams were still active until the late stage of deglaciation. Landforms transverse to ice-flow direction include grounding-zone wedges, frontal moraines, grounding-line fans, recessional moraines and De Geer moraines. These features are interpreted as the result of former standstills of the ice margin during deglaciation. The occurrence of grounding-lines in deep (˃800 m) part of the fjords contrasts with studies suggesting instability and rapid retreat of outlet glaciers over deep basins. In-between the moraines, we generally observe sediment-filled basins, often characterized by the presence of turbidity channels, gullies and mass movement scars. Sediment-filled basins with a ponded architecture between sills illustrates that most of sediment accumulation was ice-proximal and likely characterized by gravity-driven flows. We present a landform-assemblage model for northeastern Baffin fjord which includes landforms typical of different fjord landsystems.