As part of an emerging program to understand ground temperature and geothermal heat potential in Yukon, the Yukon Geological Survey drilled two temperature gradient wells in south-central Yukon: one near the Takhini Hot Springs in 2017, and a second in the Tintina Trench in 2018. This study presents the thermo-hydraulic properties of drill core from these wells and from selected outcrops, to evaluate heat transfer mechanisms in the subsurface and provide a heat flow model to characterize the geothermal potential of these regions. Thermo-hydraulic properties of the rocks in the Takhini well have a moderate thermal conductivity and a low matrix hydraulic conductivity for consolidated rocks, corresponding to a linear geothermal gradient in the upper part of the well. The rocks in the Tintina well have low thermal conductivity and hydraulic conductivity. The linear geothermal gradient indicates conductive heat transfer even though the rocks are permeable. The proximity of the well to a mountain range suggests a shallow groundwater path in the Tintina well area, with no evidence of surface hot springs.
The location of steep faults appears to be a key pathway for deep groundwater to seep to surface and can explain the geothermal context near the Takhini well. Such a framework is a typical geothermal play type in orogenic belts. Although the Tintina well is found in a similar setting, this study does not identify potential for deep forced convective groundwater flow movements because hydraulic head difference along the faults may not be enough for the deep groundwater to rise since the faults are expected to be subvertical. This research, therefore, helps to characterize the subsurface and provides critical information needed for a successful exploration of geothermal energy resources.