Late Cretaceous Volcanoplutonic Arcs in Northwestern British Columbia: Implications for Porphyry and Epithermal Deposits

Porphyry Cu and epithermal deposits are spatially and temporally related to specific volcanic and plutonic rocks emplaced during the formation of long-lived magmatic arcs formed along convergent plate boundaries (e.g., Sillitoe, 1972; Sutherland Brown, 1976; Titley, 1982; Sawkins, 1990; Bissig et al., 2003). Recognizing the presence, types of deposits, and age of the mineralized volcanoplutonic complexes in underexplored terranes is an important step toward identifying the metallogenic potential of a terrane as a means to aid exploration. Historically in British Columbia (BC), porphyry Cu deposits have dominated exploration and mining activity (e.g., Highland Valley, Gibraltar, Afton, Copper Mountain, Galore Creek). In contrast, epithermal deposits have until recently (e.g., Toodoggone district deposits) remained largely underexplored because of their low preservation potential coupled with the Mesozoic age of most of the convergent margin arcs in the western Canadian Cordillera. For example, the known porphyry Cu and several epithermal deposits in British Columbia are associated with Jurassic arcs, with the Cretaceous arc seemingly of less interest from a metallogenic viewpoint.