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TitleIce-flow and deglacial history of the Laurentide Ice Sheet in the southwestern Great Slave Lake area
AuthorHagedorn, G; Ross, M; Paulen, R; Smith, R; Neudorf, C; Gingerich, T; Lian, O
SourceGAC-MAC-IAH 2019: where geosciences converge/AGC-AMC-AIH 2019 : où les géosciences convergent; GAC-MAC-IAH Joint Meeting, Abstract volume vol. 42, 2019 p. 102 (Open Access)
LinksOnline - En ligne (complete volume, volume complet, PDF, 6.08 MB)
Alt SeriesNatural Resources Canada, Contribution Series 20180388
PublisherGeological Association of Canada
MeetingGAC-MAC-IAH 2019 / AGC-AMC-AIH 2019; Québec, QC; CA; May 12-15, 2019
Mediaon-line; digital
RelatedThis publication is related to Hagedorn, G W; Ross, M; Paulen, R C; Smith, I R; Neudorf, C M; Gingerich, T; Lian, O B; (2019). Ice-flow and deglacial history of the Laurentide Ice Sheet in the southwestern Great Slave Lake area, Northwest Territories, Geological Survey of Canada, Scientific Presentation no. 106
File formatpdf (Adobe® Reader®)
ProgramGEM2: Geo-mapping for Energy and Minerals, Mackenzie Corridor, Southern Mackenzie Surficial Mapping
Released2019 05 01
AbstractLimited field studies and sparse chronological constraints in the southwestern Great Slave Lake area creates uncertainties about the Laurentide Ice Sheet (LIS) flow history and deglacial chronology. Improved understanding of the western LIS ice-margin morphology and retreat history is required to refine larger ice-sheet interpretations and timing for northwest drainage of glacial Lake McConnell. Using new field observations and geochronology we establish ice-flow history and better constrain regional deglaciation. Paleo-ice flow indicators (n = 66) show an oldest southwestern flow (230°), an intermediate northwesterly flow (305°), and a youngest westerly flow (250°). Till samples bulk sediment and matrix properties (n = 160) allowed identification of two till units. A lower grey till sourced mainly from local Paleozoic sediments produced clast fabrics indicating a southwesterly flow direction, overlain by a brown till that contained an increased Canadian Shield content with lodged elongate boulders a-axes and boulder-top striation orientations indicating a west to northwest ice-flow direction. Ice-flow results show a clockwise shift in direction interpreted as evidence for ice-divide migration followed by topographically controlled deglacial westward flow influenced by the Mackenzie River valley. Minimum deglacial timing estimates were constrained through optical dating of fine-sand deposits in a well-developed strandline (n = 2) and seven aeolian dunes; ages range from 9.9 ± 0.6 to 10.8 ± 0.7 ka BP. These ages are from dunes located below glacial Lake McConnell maximum water level and may thus provide new local lake level age constraints. Ice retreat is informed by a newly-mapped segment of the Snake River moraine, which is an understudied feature in the region. New ice-flow history and ice-margin retreat interpretations will be integrated into the larger body of work on the western LIS providing more confident conclusions on ice-sheet evolution and meltwater drainage pathways, specifically in the southwestern Great Slave Lake area.
Summary(Plain Language Summary, not published)
GEM2 Funded MSc student presentation at Canada's national geological conference, summarizing field research and laboratory results.