STRUCTURAL CONTROLS ON THE DISTRIBUTION OF THERMAL SPRINGS IN THE CANADIAN CORDILLERA

The mountain belt of western Canada (the Canadian Cordillera) has countless low temperature springs associated with relatively shallow circulation systems. In contrast thermal springs, indicative of more deeply circulating flow systems, are relatively rare (only ~140 known occurrences). While some springs have an obvious association with high heat flow regions (e.g. the Nahanni area) and/or volcanic belts (Garibaldi, Stikine), the majority of thermal springs occur in moderate to low heat flow settings. These thermal springs show a strong relationship with regional structural geology. Across southern British Columbia springs are almost entirely restricted to crustal scale normal or strike-slip faults, and typically at the intersection of 2 major brittle structures. Thermal springs also occur in the Rocky Mountain Fold and Thrust belt, in the eastern portion of the Cordillera, which is characterized by thin-skin deformation and very low heat-flow. Here springs are associated with anomalous structures, which form complex cross cutting and steep dipping features which locally enhance permeability. The overall dip of fault planes appears to control depth of water circulation and thus temperature.