GSA Connects 2021 in Portland, Oregon

Paper No. 193-4
Presentation Time: 2:30 PM-6:30 PM


HODDER, Tyler, 283 Duffield St, Winnipeg, MB R3J 2K1, CANADA, GAUTHIER, Michelle, PO Box 795, Stonewall, MB R0C2Z0, CANADA, ROSS, Martin, Earth Sciences, 200 University Ave West, Waterloo, ON N2L3G1, CANADA and KELLEY, Samuel E., Geology, University at Buffalo, 411 Cooke Hall, University at Buffalo, Buffalo, NY 14260

The western region of the Hudson Bay Lowland (HBL) contains a long and unique geological record that can be used to investigate the complex spatio-temporal behaviour of the Keewatin and Quebec-Labrador ice dispersal centres within the Laurentide Ice Sheet (LIS). Previous till stratigraphy studies have identified multiple SE- (Keewatin) and/or NW-trending (Quebec-Labrador) ice-flow phases that crossed the area, which creates challenges when determining the ice-flow direction that deposited a specific till unit. In this study, we use till clast-lithology, till-matrix geochemistry and detrital hornblende 40Ar/39Ar ages to confidently determine till provenance. We then incorporate this robust till provenance data within detailed stratigraphic observations to show that two major NW-trending ice-flow events over-rode sorted intertill sediments at different stratigraphic positions. Both of the NW-trending ice-flow phases are interpreted to record glacial advances following non-glacial periods. The repeated advance of ice sheets emanating from the Quebec-Labrador Sector into western HBL has important implications for modelling the growth of the LIS and suggests that growth of the Keewatin Sector was slower in comparison to the Quebec-Labrador Sector, which indicates asymmetric build-up of the LIS. This study highlights several issues with the current stratigraphic framework of the western HBL and emphasizes a need to acknowledge the fragmented nature of the Quaternary stratigraphic record in order to improve the correlations within glacial sediments.