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TitleTectonic reconstruction and geophysical investigations of IOCG occurrences: Great Bear Magmatic Zone, NT
AuthorHayward, N; Corriveau, L; Enkin, R; Montreuil, J -F
Source40th Annual Yellowknife Geoscience Forum, abstracts of talks and posters; by Watson, D M (ed.); Northwest Territories Geoscience Office, Yellowknife Geoscience Forum Abstracts Volume 2012, 2012 p. 18 (Open Access)
LinksOnline - En Ligne
Alt SeriesEarth Sciences Sector, Contribution Series 20130431
Meeting40th annual Yellowknife Geoscience Forum; Yellowknife; CA; November 13-15, 2012
File formatpdf
ProvinceNorthwest Territories
NTS85N; 86C; 86D; 86E; 86F; 86K; 86L
AreaGreat Bear Lake; Lac la Martre; Hottah Lake
Lat/Long WENS-119.0000 -116.0000 67.0000 63.0000
Subjectseconomic geology; tectonics; geophysics; tectonic interpretations; tectonic environments; tectonic setting; magnetite; glacial deposits; iron oxides; copper; gold; mineralization; fluid flow; paleomagnetic interpretations; paleomagnetism; structural analyses; structural interpretations; Great Bear magmatic zone
AbstractThe Geological Survey of Canada's (GSC) Geomapping for Energy and Minerals (GEM) Program is developing and applying new techniques to iron oxide-copper-gold (IOCG) mineral exploration. The Great Bear magmatic zone (GBmz) is the remnants of a Paleoproterozoic continental magmatic arc (ca. 1.872-1.843 Ga), which hosts IOCG mineralisation, including the (Au-Co-Bi-Cu) NICO deposit. The arc, which was built upon the Hottah terrane during eastward subduction prior to accretion of the Fort Simpson terrane, is dominated by granodiorites, with mafic and volcaniclastic rocks towards the margins. Coarse grained biotite granites (ca. 1.866 - 1.856 Ga) mark the final plutonic event, which was followed by extensive NE-striking brittle faulting, related to final accretion.
A tectonic reconstruction of the GBmz, based on the interpretation of a new compilation of high-resolution aeromagnetic data and geological maps, resets major fault offsets associated with final accretion. The reconstruction provides a snapshot of the geometry of the GBmz at the time of mineralisation (ca. 1.873 - >1.866 Ga), and a tectonic model for the late-stage setting and evolution of the arc, important in understanding the context of the mineralisation. The model suggests that the NE-striking faults were preceded by extension, localised along the western side of the arc in association with NNE-striking faults, perhaps driven by shifting plate motions and slab-rollback.
Geophysical target models developed for the NICO area, which integrate proprietary high-resolution magnetic and gravity data with GSC physical property data, extracted from 651 samples collected from NICO and other sites across the GBmz, clearly delineate the primary ore zone and the majority of the local mineral showings. Applied regionally, similar models accurately locate known magnetite-group IOCG deposits, including NICO and prospects such as Grouard, Fab, DeVries and Cole Lake, the magnetite to hematite-group systems of the Port Radium-Echo Bay district, and offer possible targets for future exploration.