Unveiling Canada’s Extensional Geothermal Resources: Exploration and Assessment of the Lakelse Geothermal System, British Columbia.

The Lakelse Geothermal Field hosts an extensional, fracture-controlled, convective system located near the southern end of the Stikine Volcanic Zone, in Northwestern British Columbia, and within 60 km of one of Canada’s most recent volcanic eruptions. Historical geothermal exploration in the area was focused on the vicinity of the Mt. Layton Hot Springs, where alkali-chloride neutral waters discharge at temperatures of up to 87 °C. Despite feeding Canada’s hottest hot spring, exploration was halted for over 30 years, as the system underlies a thick glacial cover that poses unique technical challenges. Recent exploratory efforts led by the First Nations-majority owned Kitselas Geothermal Inc. include field, geophysical, and geochemical surveys followed by a core hole drilling campaign. These activities allowed for the generation of a comprehensive conceptual model of the geothermal play, the first one for the region. The Lakelse Geothermal Field is hosted within the Kitsumkalum-Kitimat Graben, developed in the Eocene as a result of arc-perpendicular collapse, and currently active under a transcurrent regime due to coupling with the Pacific Plate. Electromagnetic surveys and core hole data discovered an extensive argillic alteration zone associated with increased fracture permeability and confirmed by mineralogical analyses. Having no documented steam discharge, the system is considered to be liquid-dominated. In addition, geothermometry from hot spring samples suggests maximum fluid temperatures of over 150 °C, with potential contributions from deep-sourced acidic fluids migrating along regional crustal-scale faults. Here we present an updated geological model of the Lakelse Geothermal System together with a third-party reviewed resource estimate, highlighting the potential of this play to provide clean, renewable and baseload energy to the region while contributing to the development of British Columbia’s abundant, yet overlooked, extensional geothermal resources.