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TitleGeological investigations of the Cat Creek area in the Neoarchean Bird River greenstone belt, southeastern Manitoba (part of NTS 52L12): new insights into PGE-Ni-Cu-Cr mineralization
AuthorYang, X M; Gilbert, H P; Houle, M
SourceManitoba Department of Energy and Mines, Geological Services, Report of Activities 2012, 2012, 32-53 pages
Year2012
Alt SeriesEarth Sciences Sector, Contribution Series 20150008
PublisherManitoba Geological Survey (Winnipeg, CN)
Documentserial
Lang.English
Mediapaper
File formatpdf
ProvinceManitoba
NTS52L/12
AreaCat Creek
Lat/Long WENS-95.7167 -95.2333 50.6833 50.3833
Subjectseconomic geology; stratigraphy; greenstone belts; platinum; nickel; copper; chromium; mineralization; mineral occurrences; mineral deposits; bedrock geology; Archean; Bird River greenstone belt; Precambrian
Illustrationslocation maps; photographs; tables; plots; ternary diagrams
ProgramMafic-Ultramafic Ore Systems, Targeted Geoscience Initiative (TGI-4)
AbstractThe Cat Creek Lake area in the northern arm of the Bird River greenstone belt is situated approximately 145 km northeast of Winnipeg in southeastern Manitoba. The study area is underlain by a suite of typical greenstone assemblages within a continental margin setting adjacent to the Mesoarchean Maskwa Lake Batholith. The rock assemblages consist of a tonalite-trondhjemite-granodiorite (TTG) suite, supracrustal rocks including mafic to felsic volcanic and synvolcanic intrusive rocks, epiclastic and minor volcaniclastic rocks, the Mayville mafic-ultramafic layered intrusion, and late peraluminous granitoids and related pegmatite. The Mayville intrusion consists of an east-trending lopolith approximately 10.5 km in length and up to 1.5 km in width. The intrusion is emplaced in a mid-ocean ridge basalt (MORB) sequence to the south and west, and is in structural contact with granitoid rocks to the east. To the north, the Mayville intrusion is emplaced in metasedimentary and intercalated volcaniclastic rocks, and is locally structurally juxtaposed against granitoid rocks. Although the Mayville intrusion has recently been the focus of on-going mineral exploration because it hosts a significant amount of PGE-Ni-Cu-Cr mineralization, some key metallogenetic questions remain to be answered.
This report presents the preliminary results of geological mapping at a scale of 1:12 500 conducted by the Manitoba Geological Survey in 2012, together with new petrological, lithogeochemical, and geochronological data acquired within the last year. Twelve map units have been identified in the Cat Creek area. The mapping and geochemical study suggest that the MORB-type basalts and related intrusive rocks, as well as the Mayville intrusion, may have been emplaced in an extensional back-arc environment characterized by a relatively thin crust (~21 km) and a continental margin setting. The present geological map data indicate that the Neoarchean Mayville intrusion (U-Pb zircon age of 2743 ± 1 Ma) consists dominantly of anorthositic gabbro, gabbroic anorthosite and anorthosite, with subordinate melagabbro and pyroxenite at the base and gabbro at the top. This intrusion is similar to Archean anorthosite complexes elsewhere, and can be subdivided into a lower heterolithic breccia zone and an upper anorthosite to leucogabbro zone. The geochemical signature of the Mayville intrusion suggests the parental magma(s) was an alumina-enriched tholeiitic type that may have been derived from a high-degree of partial melting of the subcontinental lithospheric mantle; it may have experienced assimilation and fractional crystallization during its emplacement within the supracrustal rock succession. An early sulphide saturation event triggered by crustal contamination and/or introduced external sulphur is likely to have generated magmatic sulphide Ni-Cu-PGE mineralization at the base of the intrusion. The injection of a new batch(s) of a mafic-ultramafic melt may have resulted in PGE and chromite mineralization at transitional zones between various phases within the intrusion. In addition, it is noted that calcic anorthosite in the Mayville intrusion may represent a potential source for the manufacture of aluminum-bearing chemicals.
Summary(Plain Language Summary, not published)
The Targeted Geoscience Initiative (TGI-4) is a collaborative federal geoscience program that provides industry with the next generation of geoscience knowledge and innovative techniques to better detect buried mineral deposits, thereby reducing some of the risks of exploration. This report presents the preliminary results of geological mapping at a scale of 1:12 500 conducted by the Manitoba Geological Survey in 2012, together with new petrological, lithogeochemical, and geochronological data acquired within the last year. Twelve map units have been identified in the Cat Creek area a succession of supracrustal rocks and the Mayville intrusion.
GEOSCAN ID296298