Geology and Evolution of Gold Deposits, Timmins Area, Ontario

Special Volume, Vol. SV 24, No. 1982, 1982

In the Timmins area, a close spatial and chronological association exists between gold deposits and two major stratabound carbonate-rich members and related quartz-feldspar porphyries. Synvolcanic and metamorphogenic are the two main types of mineralization recognized. Synvolcanic ores include the stratiform quartz-ankerite "veins", pyritic carbonates and chert-carbonate-tuff sedimentary rocks and epigenetic ventrelated breccias and stringer zones. Metamorphogenic ores consist of quartz-carbonate fracture fillings in dilatant zones developed during various phases of regional deformation and metamorphism. They are classically epigenetic in character. The evidence suggests a primary syngenetic enrichment of gold on the ocean floor and in vent areas during submarine felsic volcanism and related exhalative-hydrothermal activity followed by further enrichment into quartz-carbonate stockworks during regional deformation and greenschist metamorphism. Although normally thin (a few hundred metres), carbonate members in Archean volcanic terrain represent intense hydrothermal activity which could have transported and enriched gold. They should be used to locate fossil vents and structurally favourable zones where economic concentrations of gold may be found.

Mots Clés: Gold, gold deposits, geology, Timmins, submarinefelsic volcanism, hydrothermal activity