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TitleThe world-class Musselwhite BIF-hosted gold deposit, Superior Province, Canada: new high-precision U-Pb geochronology and implications for the geological setting of the deposit and gold exploration
AuthorMcNicoll, V; Dubé, B; Castonguay, SORCID logo; Oswald, W; Biczok, J; Mercier-Langevin, P; Skulski, TORCID logo; Malo, M
SourcePrecambrian Research vol. 272, 2016 p. 133-149,
Alt SeriesEarth Sciences Sector, Contribution Series 20150050
PublisherElsevier BV
Mediapaper; on-line; digital
File formatpdf
AreaNorth Caribou Lake
Lat/Long WENS -91.5000 -90.5000 53.0000 52.5000
Subjectsgeochronology; general geology; iron formations; uranium lead dates; zircon dates; epigenetic deposits; exploration activities; Superior Province; North Caribou greenstone belt
Illustrationsgeological sketch maps; location maps; tables; photographs; Concordia diagrams
ProgramTargeted Geoscience Initiative (TGI-4) TGI-4 Program Coordination
Released2015 10 19
New high-precision U-Pb ages from the 5.7 Moz Au Musselwhite banded iron formation (BIF)-hosted epigenetic gold deposit and host succession in the North Caribou greenstone belt of the Superior Province provide timing constraints on the setting of the deposit, with implications for regional geological and exploration models. The deposit is mainly hosted by a folded garnet-grunerite-chert silicate facies of the Northern BIF, part of the Opapimiskan-Markop assemblage. Dating of a volcaniclastic sedimentary rock and a garnet-biotite +/- staurolite schist both indicate that the Northern BIF is <2967 Ma. A ca. 2909 Ma foliated felsic dike further constrains the age of the Northern BIF and provides a maximum age for D2 deformation. Felsic tuff (ca. 2979 Ma) from the South Rim volcanic assemblage structurally overlies the ore-bearing Northern BIF. These data combined with stratigraphic and field evidence indicate that the deposit host succession is overturned, probably due to early F1 folding, which is documented in areas of lower D2 strain. Felsic ash tuff and a fine-grained siliciclastic sedimentary rock from the 'Lower Sediments' unit (Zeemel/Eyapamikama assemblage) have much younger ages of <2850 Ma and <2846 Ma, respectively. The ~120 m.y. time gap between the latter and the structurally overlying Opapimiskan-Markop assemblage is coincident with the location of a high-strain zone within iron-carbonatized ultramafic rocks. The youngest supracrustal assemblage in the studied area is similar to Timiskaming-type sedimentary rocks of the Southern Abitibi greenstone belt and therefore, the unconformity/thrust contact between volcanic and sedimentary assemblages may constitute a key gold exploration target.
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 gold mine is located in the geological Superior Province, 500 km north of Thunder Bay, Ontario. In this study the ages of the rocks that host the gold deposit have been determined. They have helped determine that there is a major fault or break in the succession, with rocks on one side of the fault that are 120 million years younger than those on the other side. These structural complications to the rock succession are some of the factors that have contributed to a favourable environment for gold. The new age results have important implications for gold exploration in both the local and regional geological areas in the Superior Province.

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