Structural evolution, geochemistry, and geochronology of the Magino Gold Deposit, Michipicoten Greenstone Belt, Northern Ontario

Abstract

The Magino gold mine is located approximately 40 km northeast of the town of Wawa within the Michipicoten greenstone belt of the Archean Wawa subprovince. Mineralization is hosted by the ca. 2724 Ma tonalitic Webb Lake stock within the Goudreau Lake Deformation Zone. The Magino deposit formed during two gold mineralization events. The first mineralizing event is coeval with the emplacement of the Webb Lake stock and is manifested by corridors of strong phengite/muscovite-quartz-pyrite alteration and saccharoidal quartz veins. The latter are dated at 2731 ± 6.9 Ma (Re-Os molybdenite) and overlap within error with the age of the host intrusion. The second gold mineralization event is associated with epigenetic quartz-tourmaline-carbonate veins, which were emplaced during the formation of the steep regional foliation along the Goudreau Lake Deformation Zone. The Magino deposit is an excellent example of an Archean intrusion-related gold system later overprinted by deformation, orogenic mineralization, and metamorphism.