Controls on the distribution of thermal springs in the southern Canadian Cordillera

Thermal springs examined in southern British Columbia are restricted to six major Eocene or later brittle fault systems. These faults provide a high-permeability flow path that allows for deep circulation of meteoric water. The depth of circulation, and thus temperature, is largely influenced by fault plane geometry. Calculated circulation depths of up to 4.8 km are consistent with models for hydrothermal ore deposits that invoke the mixing of mineralizing fluids with sulphur-rich meteoric water at depth. Mass-flux calculations indicate that a relatively small spring (5 L/s) can transport large amounts of bacterially reduced sulphur to ore-forming depths over a short geological time scale and can easily account for the sulphur associated with Pb–Zn deposits in the southern Canadian Cordillera. Modern thermal springs may be good analogies for the upper-crustal flow systems in hydrothermal ore deposit models.