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TitleRegional glacial history, paleo-dynamics and dispersal patterns, South Rae craton, Northwest Territories
AuthorCampbell, J E; Lauzon, G; Dyke, A S; Roy, M
SourceGAC-MAC 2017; Geological Association of Canada-Mineralogical Association of Canada, Joint Annual Meeting, Programs with Abstracts 2017, 2017. Open Access logo Open Access
LinksOnline - En ligne
Alt SeriesEarth Sciences Sector, Contribution Series 20160446
PublisherGeological Association of Canada
PublisherMineralogical Association of Canada
MeetingGeological Association of Canada-Mineralogical Association of Canada Joint Annual Meeting 2017; Kingston, ON; CA; May 14-18, 2017
Mediapaper; on-line; digital
ProvinceNorthwest Territories
NTS75A; 75B; 75G; 75H
AreaKeewatin Sector
Subjectseconomic geology; industrial minerals; regional geology; geological surveys; mineral exploration; till deposits; tills; till analyses; glacial history; glacial deposits; deglaciation; ice movement directions; indicator elements; Laurentide Ice Sheet (LIS); Dubawnt SuperGroup
ProgramGEM2: Geo-mapping for Energy and Minerals South Rae Province Bedrock/Surficial geology
Released2017 01 01
AbstractThe southern Rae area in southwest Northwest Territories lies within one of the most poorly mapped and least understood regions of the Keewatin Sector of the Laurentide Ice Sheet (LIS). This region is heavily covered by glacial sediments, which impede both bedrock mapping and mineral exploration. To fill in this knowledge gap, recent regional-scale (1:250 000) mapping and till sampling in four NTS mapsheets (75A, B, G and H) has been undertaken, revealing complex surficial geology and glacial history in this region.
The glacial landscape records a complex history of changing glacial flow dynamics and subglacial conditions during deglaciation, as reflected by superimposed landforms, juxtaposed streamlined terrain (fast flow) and non-streamlined terrain (sticky spot/sluggish flow) and a network of WSW-SW trending subglacial meltwater corridors. Sediment/landform associations reflect variations in sediment transport distances, directions and degree of inheritance.
Field-based measurements of erosional ice-flow indicators (e.g. striations, roches moutonnées) and imagery mapping of streamlined landforms record at least five regional flow sets attributed to Wisconsinan glaciation. The oldest flow is recorded at a few sites as striations with unknown sense (SSE/NNW). Well-defined indicators reveal a clockwise rotation in regional ice-flow directions during the Late Wisconsin glacial/deglacial event, shifting from southward to southwestward flow. A late westward flow is recorded in the north half of the study area. The prevailing regional ice-flow direction is to the southwest.
Till composition data (clast lithology, indicator minerals, matrix geochemistry and texture) combined with ice-flow indicators are examined to establish sediment dispersal patterns as well as the varying degrees of till inheritance and hybridization. Preliminary results indicate that at the regional scale, till composition predominantly reflects the bedrock domains with sharp changes in lithological and geochemical constituents across domain boundaries. Distinctive erratics and exotic clast lithologies in the till are used as tracers for glacial dispersal patterns and compositional inheritance. Clasts, such as Dubawnt Supergroup lithologies, derived from sources located to the north-northeast of the study area, indicate sustained transport of glacial debris by the older southward flow.
This research will provide much needed input for the paleoglaciological reconstruction of the Keewatin Sector of the LIS, and a much needed Quaternary geological framework for mineral exploration and land resource management in the southwest region of the Rae geological province.
Summary(Plain Language Summary, not published)
This presentation outlines the preliminary interpretation of data from the surficial mapping and till sampling field work completed in southeast Northwest territories, as part of the surficial geology component of the GEM-2 South Rae Activity. The presentation focuses glacial terrain zones,ice-flow reconstruction, glacial sediment transport patterns and till composition. Implications of results are discussed.

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