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TitleInto the unknown part 2: Surficial geological investigations in the South Rae, Northwest Territories
AuthorCampbell, J E; Lauzon, G; Dyke, A S; Haiblen, A M
Source2016 Yellowknife Geoscience Forum, abstract and summary volume; by Irwin, D; Gervais, S D; Terlaky, V; Northwest Territories Geological Survey, Yellowknife Geoscience Forum Abstract and Summary Volume 2016, 2016 p. 8-9 Open Access logo Open Access
LinksOnline - En ligne (complete volume - volume complet, PDF, 1.72 MB)
Alt SeriesEarth Sciences Sector, Contribution Series 20160258
PublisherNorthwest Territories Geological Survey
Meeting44th Annual Yellowknife Geoscience Forum; Yellowknife, NT; CA; November 15-17, 2016
File formatpdf
ProvinceNorthwest Territories
NTS75I/01; 75G; 75H
Lat/Long WENS-104.5000 -104.0000 62.2500 62.0000
Subjectssurficial geology/geomorphology; geochemistry; bedrock geology; tills; indicator elements; ice flow; erosion; deglaciation; drift deposits; eskers; glaciofluvial deposits; mineral exploration; South Rae Craton
ProgramGEM2: Geo-mapping for Energy and Minerals South Rae Province Bedrock/Surficial geology
Released2016 01 01
AbstractThe Geological Survey of Canada, as part of its Geo-Mapping for Energy and Minerals Program (GEM2), in partnership with the Northwest Territories Geological Survey, is in the second year of a project to upgrade the bedrock and Quaternary geoscience knowledge for the underexplored and predominantly drift-covered South Rae Craton in southeastern Northwest Territories. During the 2016 field season, surficial geological mapping and till sampling was conducted in NTS map sheets 75G and H. Targeted reconnaissance sampling (~15 km spacing) resulted in 109 till samples collected at 103 sites for provenance, geochemistry, indicator minerals and gold grains. Multiple small and meso-scale erosional ice-flow indicators (e.g. striations, grooves, roche moutonnée) were measured at 109 locations. To help establish a minimum age for deglaciation in this area, samples were collected for age dating from 3 beach or delta sites (optically stimulated luminescence) and 5 boulder sites (terrestrial cosmogenic nuclides).
Preliminary mapping has identified at least 4 phases of ice flow with 2 main flowsets variably affecting the entire study area. An old flow of unknown sense (SSE/NNW) and temporal relationship was recorded at a few sites. An old regional southward flow is overprinted by the main regional southwest flowset (Late Wisconsin deglaciation). A late (youngest) west flow overprints this southwest flow.
Distinctive erratics, such as Dubawnt Supergroup lithologies derived from sources located to the north-northeast are more prevalent than in the 2015 map area to the south. This is consistent with sustained transport and dispersal of glacial debris by the older southward flow.
Drift cover of variable thickness is extensive, with bedrock exposure ranging from 0 to 30%. The dominant surficial material is till of varying composition, thickness and genesis. The till becomes sandier northward likely reflecting an increased Thelon sandstone component in the till. The landscape, particularly in northeastern 75G and much of 75H is dominated by streamlined landforms with organic terrain in the lows. Numerous parallel NE - SW trending eskers systems and subglacial meltwater corridors cross the map area with two types of signature landform/deposits assemblages: 1) eskers, parallel trains of either ice-contact glaciofluvial (hummocks and ridges) deposits or terraced glaciofluvial deposits, and 2) trains of hummocky till, boulder lags, exposed bedrock with small discontinuous eskers and related deposits. New mapping has continued to delineate the extent of glacial lakes in this region. The reworking of the existing glacial and glaciofluvial deposits below 410-420 m elevation has resulted in a widespread veneer of sands and sandy diamictons over the low relief terrain.
The 1:100 000 scale surficial geological mapping, together with reconnaissance-scale till sampling, will provide new data and improved understanding of the glacial history in support of mineral exploration, sustainable resource development and land-use management for the South Rae region.
Summary(Plain Language Summary, not published)
This poster highlights the results from the GEM2 South Rae surficial mapping sub-activity. This data will provide the framework for mineral exploration and baseline assessments to inform land management decisions in this region.

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