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TitleHighlights of regional geology and mineral potential from 2016 mapping in south Rae Province, NWT
AuthorMartel, E; Percival, JORCID logo; Pehrsson, S J; Acosta-Góngora, P; Regis, D; Thiessen, E; Jamison, D; Neil, B; Knox, B
Source44th Annual Yellowknife Geoscience Forum abstracts; Northwest Territories Geological Survey, Yellowknife Geoscience Forum Abstract and Summary Volume 2016, 2016 p. 92-93 Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20190437
PublisherNorthwest Territories Geological Survey
Meeting44th Annual Yellowknife Geoscience Forum; Yellowknife, NT; CA; November 15-17, 2016
Mediaon-line; digital
File formatpdf
ProvinceNorthwest Territories
Subjectseconomic geology; mineralogy; Science and Technology; Nature and Environment; Rae Province
ProgramGEM2: Geo-mapping for Energy and Minerals South Rae Province Bedrock/Surficial geology
Released2016 11 01
AbstractThe South Rae Province in the Northwest Territories has seen little research since it was first mapped by canoe and float plane at reconnaissance scale in the 1950-1960s. Under the GEM2 program, the collaborative GSC-NTGS South Rae 1:250,000-scale bedrock mapping project is improving understanding of the evolution, economic potential and role of this region in assembly of the Canadian Shield. Field work in 2016 was focused in NTS 75G and the western half of 75H and covered over 17,500 km2 of previously unmapped ground. This mapping provides insights on six new, informally-named, geophysically and isotopically defined domains, each with a distinct record of magmatic and tectono-metamorphic events and metallogenic potential. The domains have boundaries that strike roughly northeast-southwest and are described from southeast to northwest. The Firedrake domain comprises ca. 2.66 Ga felsic to intermediate orthogneiss, mafic to ultramafic rocks and rare paragneiss, all injected by widespread migmatitic granitoids. This domain shows evidence for early 1.89 Ga granulite metamorphism at 8-11 kbar and subsequent decompression to 4-6 kbar amphibolite conditions around 1.84 to 1.80 Ga. The McCann domain consists mainly of biotite +/-garnet+/-orthopyroxene tonalite, granodiorite and granite, with sparse mafic-ultramafic rocks, paragneiss and iron formation enclaves, cut by ca. 2.15 Ga Orpheous gabbro dykes. It records the medium pressure and high temperature Arrowsmith orogeny at ca. 2.45-2.32 Ga and ca. 1.88 Ga metamorphism at minimum 8 kbar. The Penylan domain includes hornblende-clinopyroxene +/- garnet anorthositic gabbro, massive to variably foliated monzogranite and quartz diorite which all yield crystallization ages between 2.03-2.05 Ga. The anorthosite-gabbro complex is much larger than previously mapped extending over 100 km northeast-southwest. The Howard Lake domain is defined by an intense magnetic low and includes distinct rocks such as andalusite-bearing wacke, muscovite schist, biotite schist, and calc-silicate, as well as foliated to gneiss granodiorite, anorthositic orthopyroxene gabbro, and granite. Preliminary synthesis suggests the newly mapped surpracrustal rocks are a continuation of the sequence that hosts the Boomerang U deposit to the north. The Lynx Lake domain is comprised of granodiorite to tonalite with abundant enclaves of surpracrustal origin, including basaltic schist, plagioclase-phyric andesite, sillimanite-garnet-biotite paragneiss and iron formation. The Porter domain consists mainly of hornblende-biotite and orthopyroxene-clinopyroxene bearing granodiorite with gabbroic enclaves and dykes. Broad zones of cataclastic and brittle-ductile greenschist-facies deformation and associated chlorite-hematite-epidote alteration are widespread. The boundaries between the various domains are generally characterized by ductile high strain and appear to be the locus of multiple movements. Preliminary mapping suggests a widely distributed alkali magmatic event along the Firedrake-McCann boundary where some newly mapped syenite bodies exhibit a similar mineralization style to that responsible for Hoidas deposit (REE, U and Au) in northern Saskatchewan. Various young and poorly constrained (2.20-1.74 Ga?) clastic sequences have been mapped and may be correlative with the Nonacho, Amer and Wharton groups. The presence of Proterozoic Nonacho Group sedimentary rocks unconformably overlying the Porter domain highlights the potential for U and Au deposits in this poorly explored area of the NWT.

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