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TitleRecent advances in our understanding of the Brock Inlier, Northwest Territories
AuthorRainbird, R HORCID logo; Craven, J A; Rayner, NORCID logo; Turner, E C; Ielpi, A; Bouchard, M; Javaux, E; Jackson, V A; Fischer, B J; Greenman, J W; Gibson, T
SourceMargins through time: GAC-MAC 2016; Geological Association of Canada-Mineralogical Association of Canada, Joint Annual Meeting, Programs with Abstracts vol. 39, 2016 p. 75 Open Access logo Open Access
LinksOnline - En ligne (complete volume - volume complet, PDF, 1.3 MB)
Alt SeriesNatural Resources Canada, Contribution Series 20190419
PublisherGeological Association of Canada
MeetingGAC-MAC 2016; Whitehorse, YK; CA; June 1-3, 2016
Mediaon-line; digital
File formatpdf
ProvinceNorthwest Territories
AreaDarnley Bay
Subjectsstratigraphy; paleontology; geochronology; Science and Technology; Nature and Environment; Brock Inlier
ProgramGEM2: Geo-mapping for Energy and Minerals Mackenzie Corridor, Shield to Selwyn
Released2016 06 01
AbstractOur studies of Brock Inlier comprise an activity within the GSC's GEM2 Mackenzie Shield to Selwyn geo-transect: studying the evolution of sedimentary rocks of the northern mainland NWT to improve exploration success. The Brock Inlier, an uplifted region of mostly early Neoproterozoic sedimentary rocks surrounded by lower Paleozoic and Cretaceous sedimentary rocks, is located just east of Darnley Bay, Northwest Territories. It overlies the eastern edge of the Darnley Bay anomaly, the largest gravity and magnetic anomaly measured in North America. Preliminary responses from 17 magneto-telluric survey stations along an E-W profile over the anomaly indicate that the overall thickness of the sedimentary succession above it is considerably greater along the western portion of the profile and suggest a conductive feature in the vicinity of the known anomaly. Our stratigraphic work has documented the first complete detailed record of the early Neoproterozoic Shaler Supergroup and Cambrian-Ordovician Mt Clark, Mt. Cap and Franklin Mountain formations; sandstone, shale and carbonate rocks exposed along the Hornaday River. Samples of these rocks have been collected for paleontological, geochronological and geochemical analysis. Preliminary analysis of shales from the Shaler Supergroup reveals a microfossil assemblage characteristic of other late Mesoproterozoic-early Neoproterozoic successions including: unambiguous eukaryotes (process-bearing acritarchs) Trachyhystrichosphaera aimika (~1.1 - 0.75 Ga) and Dictyosphaera sp. (~1.6 - 0.8 Ga; first reported occurrence in Canada). Stable C-O isotope values from the Mikkelsen Islands Formation offer stratigraphic variations that are consistent with possibly correlative carbonate-bearing successions in the northern Cordillera, > 500 km to the southwest. Samples of fluvial quartz arenite collected from the base and top of the Nelson Head Formation have almost identical detrital zircon U-Pb concordia age profiles with overwhelmingly Mesoproterozoic age sources, interpreted to have been mainly from the Grenville Province of eastern Laurentia. Helicopter-supported regional geological reconnaissance and selected ground traverses in key areas of NTS 97A (Erly Lake) and 97D (Brock River) are allowing us to build new and improved geological maps. This work is being aided by processing and analysis of newly acquired, high resolution remotely sensed and video imagery.

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