|Title||Regional glacial history, paleo-dynamics and dispersal patterns, South Rae craton, Northwest Territories|
|Author||Campbell, J E; Lauzon, G; Dyke, A S; Roy, M|
|Source||GAC-MAC 2017; Geological Association of Canada-Mineralogical Association of Canada, Joint Annual Meeting, Programs with Abstracts 2017, 2017.|
|Links||Online - En ligne|
|Alt Series||Earth Sciences Sector, Contribution Series 20160446|
|Publisher||Geological Association of Canada|
|Publisher||Mineralogical Association of Canada|
|Meeting||Geological Association of Canada-Mineralogical Association of Canada Joint Annual Meeting 2017; Kingston, ON; CA; May 14-18, 2017|
|Media||paper; on-line; digital|
|NTS||75A; 75B; 75G; 75H|
|Subjects||economic 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|
|Program||South Rae Province Bedrock/Surficial geology, GEM2: Geo-mapping for Energy and Minerals|
|Abstract||The 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
|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.