Northeastern Section - 53rd Annual Meeting - 2018

Paper No. 44-11
Presentation Time: 1:30 PM-5:30 PM


COUETTE, Pierre-Olivier, Geography, Université Laval, 51 rue Bigaouette, Québec, QC G1K4K7, Canada; Centre d'études nordiques, Québec, QC G1V0A6, Canada

The maximal extent of the Laurentide Ice Sheet (LIS) on eastern Baffin Island has been widely debated during the last decades as different palaeoglaciological models have been proposed, ranging from a single-domed ice sheet extending beyond the shelf break to an ice sheet margin barely reaching the head of the fjords. Spatial and temporal variability of ice sheets extension on eastern Baffin Island during Quaternary glaciations complicate the establishment of a reliable reconstruction of the ice margin. Furthermore, the lack of geophysical data in most of the fjords, and seaward, makes it difficult to reconcile the proposed terrestrial and marine glacial margins at the Last Glacial Maximum (LGM). High-resolution swath bathymetry imagery and acoustic stratigraphy data would therefore improve existing regional models of the extent and dynamics of the formerly marine-based LIS margin.

Here we use high-resolution swath bathymetry imagery combined with acoustic stratigraphy data collected during a recent oceanographic expedition onboard the RV Maria S. Merian to: (1) define the maximal extent of the LIS margin in Clyde Trough during the LGM; (2) reconstruct ice-flow variations and glacial dynamics in the course of the ice retreat; and (3) identify periods of stillstands and/or readvances during deglaciation.

Geomorphological mapping of Clyde Inlet and its adjacent continental shelf allowed the identification of glacial landforms, such as crag-and-tails and mega-scale glacial lineations (MSGLs), which are indicators of fast-flowing ice (i.e., ice streams). The swath bathymetry imagery also allows delineating grounding-zone wedges (GZWs) in the trough, indicating positions of stability of LIS margins during the LGM and deglaciation. Several moraines are observed in the fjord, suggesting that ice retreat occurred by steps in a less catastrophic way than previously proposed. Sediments cores collected during the summer of 2017 will provide additional insight on the deglacial environment, which will complement the analyses on reconstructing palaeo-ice dynamics on eastern Baffin Island.