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TitleNew insights on the geological and structural settings of the Musselwhite banded iron-formation-hosted gold deposit, North Caribou greenstone belt, Superior Province, Ontario
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AuthorOswald, W; Castonguay, S; Dubé, B; Malo, M; Mercier-Langevin, P; Biczok, J
SourceGeological Survey of Canada, Current Research (Online) 2015-3, 2015, 22 pages, https://doi.org/10.4095/295570
Year2015
PublisherNatural Resources Canada
Documentserial
Lang.English
Mediaon-line; digital
File formatpdf
ProvinceOntario
NTS53B/09; 53B/10; 53B/15; 53B/16
AreaNorth Caribou Lake; Opapimiskan Lake; Schade Lake
Lat/Long WENS-92.0000 -79.5000 53.0000 48.0000
Subjectsstructural geology; economic geology; structural analyses; structural features; antiforms; deformation; cherts; iron; iron formations; Archean; gold; mineral deposits; exploration; metallogeny; ore mineral genesis; fault zones; Algoma type iron formations; Algoma type deposits; mineralization; bedrock geology; Musselwhite mine; North Caribou greenstone belt; Northern Iron Formation; Musselwhite deposit
Illustrationslocation maps; stereonets; photographs; block diagrams
ProgramGold Ore Systems, Targeted Geoscience Initiative (TGI-4)
LinksErratum
Released2015 05 12
AbstractThe Musselwhite mine is a world-class gold deposit hosted in polydeformed amphibolite-facies banded iron-formation of the Mesoarchean North Caribou greenstone belt, northwestern Superior Province. The deposit is located about 2 km west of the tectonic boundary with the gneissic Island Lake domain. Detailed underground and surface mapping, core logging, and structural analyses have been undertaken to better characterize the various controls on gold mineralization. The west antiform trench 1 and esker docks exposures show the dominant northwest-trending structural pattern related to the main (D2) deformation phase. Multiple metre-scale type 3 F1-F2 and F2-F3 fold interference patterns are documented in the banded iron-formation. Coupled with regional-scale geological and U-Pb geochronological data, structural observations by the authors suggest that the mine area is located along the overturned limb of a kilometric-scale F1 syncline that influenced the regional distribution and geometry of the prospective banded iron-formation units, preceding the main D2 deformation. Underground mapping of the 1045 main ramp and 770 level 11780N crosscut sections indicates that the ore, in the northern iron-formation, mainly occurs as stratabound pyrrhotite-rich replacements and associated quartz-flooding of the garnet-rich silicate banded iron-formation facies, and locally as discordant syndeformation quartz±pyrrhotite veins. The ore zones are associated with D2-related high-strain zones, and are concentrated in hinges and along strongly attenuated limbs of F2 folds. The composition of the garnet-rich silicate facies and layered mechanical anisotropy induced by competent banded iron-formation horizons embedded in less competent mafic and ultramafic volcanic rocks strongly influenced the deformation style and played an important role in controlling flow of gold-bearing fluids and formation and distribution of the ore.
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. The Musselwhite mine is a world-class gold deposit hosted by polydeformed metamorphosed banded iron formation (BIF) located in the Archean North Caribou greenstone belt, northwestern Superior Province. Detailed mapping and structural analysis of key stripped outcrops in the mine area and underground workings have been undertaken to better understand the geometry and structural controls of the deposit and its host rocks. Two large outcrops have been mapped in detail. Observations suggest the presence of an early map-scale fold that influenced the distribution and geometry of the BIF units hosting the bulk of gold mineralization.
GEOSCAN ID295570