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TitleLac Soisson Intrusive Suite: a potential extension of the Nain Plutonic Complex in the western Core Zone, Quebec
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AuthorCorrigan, D; Wodicka, N; Lafrance, I; Bandyayera, D
SourceGeological Survey of Canada, Scientific Presentation 99, 2019, 1 sheet, https://doi.org/10.4095/314596 (Open Access)
Image
Year2019
PublisherNatural Resources Canada
Documentserial
Lang.English; French
Mediaon-line; digital
File formatpdf (Adobe® Reader®)
ProvinceQuebec
NTS24G
AreaNunavik; Lac Saffray; Lac La Moinerie; Rivière à la Baleine
Lat/Long WENS -68.0000 -66.0000 58.0000 57.0000
Subjectseconomic geology; regional geology; stratigraphy; structural geology; geochronology; tectonics; geophysics; mineral deposits; mineral exploration; nickel; copper; mineralization; tectonic history; emplacement; intrusions; plutons; dykes; crystallization; bedrock geology; lithology; intrusive rocks; mafic intrusive rocks; gabbros; troctolites; migmatites; metatexites; diatexites; metamorphic rocks; structural features; faults; lineaments; shear zones; radiometric dating; uranium lead dating; lead lead dates; mass spectrometer analysis; correlations; geophysical surveys; aeromagnetic surveys; magnetic interpretations; Archean; Core Zone; Lac Soisson Intrusive Suite; Nain Plutonic Suite; Rivière George Shear Zone; Rivière Marralik Shear Zone; Lac Pingiajjulik Fault; Winnie Suite; Qurlutuq Complex; Rivière False Suite; Mesoproterozoic; gabbronorites; platinum group elements; geological mapping; extension; Precambrian; Proterozoic
Illustrationsgeoscientific sketch maps; photomicrographs; photographs; Concordia diagrams
ProgramHudson/Ungava Core Zone, GEM2: Geo-mapping for Energy and Minerals
ProgramPolar Continental Shelf Program
Released2019 04 23
AbstractThe Lac Soisson intrusive suite consists of a swarm of small plutons and plugs of olivine-gabbro, gabbronorite and troctolite composition that were emplaced into Archean to Paleoproterozoic crust of the western Core Zone, west of the de Pas Batholith. These intrusions are essentially non-metamorphosed, with unaltered olivine visible in hand specimen and thin section. They were mapped in detail by the Ministère de l'Énergie et des Ressources naturelles (MERN) in 2013 as part of the Lac Saffray mapping project in the Core Zone, and revisited this past summer where a B.Sc. Honours thesis was initiated (Fleury, 2016), supported by the MERN. In 2000-2002, these intrusions had been targeted by the Western Mining Corporation (WMC) as part of their 'Quebec-7' Ni-Cu-PGE exploration program along the western margin of the SE Churchill Province. Some of the values reported by WMC range up to 2% chalcopyrite, < 2% pentlandite and 108 ppb PGEs over meter-length sections in drillcore. During our targeted mapping in 2014 we sampled one of the main gabbroic phases of the intrusion for U-Pb dating. The sample yielded abundant, large baddeleyite and zircon crystals, which were analyzed at the Geological Survey of Canada laboratory in Ottawa. Preliminary TIMS results stemming from the baddeleyite ages suggest that the magma was emplaced at 1312 ±1 Ma, slightly younger than the ca. 1333 ± 1 Ma Ni-bearing intrusions of the Voisey's Bay complex in Nain. Zircon from the same Lac Soisson sample, however, yields a younger SHRIMP concordia age of 1295 ±11 Ma. Interestingly, some of the Voisey's Bay zircons yield ages that are compatible with baddeleyite ages (1333 Ma), whereas others yield ages that are significantly younger, at ca. 1305 Ma. During the summer 2014, east-west oriented olivine gabbro dykes were also mapped and sampled as part of the regional mapping program. These E-W dykes are parallel to a set of crustal-scale faults and lineaments that appear to be associated to crustal extension related to emplacement of the Nain Plutonic Suite. Some may in turn be feeders to the Lac Soisson intrusions. However, preliminary TIMS results suggest an age of ca. 1270 Ma for one of these dykes. The age correlation shown herein suggests that Ni-Cu mineralized, olivine-bearing mafic intrusions of the Soisson Suite may very likely be related to the Voisey's Bay intrusions but were emplaced more than 300 km to the W-NW of the latter, in the western margin of the Core Zone.
Summary(Plain Language Summary, not published)
This poster, presented at the Géologie Quebec conference in November 2015, provides details of a new U-Pb age obtained on a norite from the Lac Soisson intrusive complex, which now makes it part of the Nain Plutonic suite. This means that potential for Voisey's Bay Ni-Cu-PGE mineralization may extend as far as 300km further west of presently known occurrences.
GEOSCAN ID314596