Magmatism, metamorphism and deformation at Hemlo, Ontario and the timing of Au-Mo mineralization in the Golden Giant mine

The Golden Giant mine is developed in the Archean Hemlo gold-molybdenum deposit hosted within the Hemlo-Heron Bay greenstone belt in NW Ontario, Canada. The ore occurs in steeply dipping tabular zones within metasedimentary rocks and within quartz-eye muscovite schists in association with microcline-mica-pyrite alteration, and a variety of other minerals. It is proposed that the primary Au-Mo mineralization occurred before the M₁ metamorphic event, possibly related to emplacement of the Golden Giant quartz porphyry in a premineralization structural zone. The mineralization was modified by the M₁ event, and severely deformed during mylonitization. Dikes from the Cedar Creek stock intruded the deposit sequence and overprinted the M₁ event with an M₂ metamorphism. -from Authors