Four years after the first Yukon Geoscience Planning Workshop (the Marsh Lake Workshop, Yukon Geoscience - A Blueprint for the Future, Yukon Geology Program, March, 1995), forty-two representatives of industry, academia, and government met at the High Country Inn in Whitehorse to re-examine the state of Yukon geoscience. Over two days, with the expert facilitation of Steve Morison, Gartner Lee Ltd., the participants reviewed the first plan, the work that was done since 1995, and produced a new set of priorities to guide Yukon geoscience into the next millenium. The 1999 Yukon Geoscience Planning Workshop had a format similar to the 1995 workshop and many of the original participants were able to attend. This continuity greatly added to the quality and credibility of the input.

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As part of the Canadian government’s commitment to establishing clean energy in the North, the Yukon Geological Survey is collecting subsurface temperature data near communities in the southern part of the territory. The research is a collaborative effort among federal and territorial geoscientists, universities, First Nation governments, and geothermal consultants. A major goal of the project is to determine whether ground temperatures warrant further geothermal exploration in the territory. The study also presents an opportunity for Yukon Geological Survey to educate the public about geothermal energy. This paper summarizes the methods and results of the drilling of two ~500 m geothermal temperature gradient wells. The first was drilled in the fall of 2017 in the Whitehorse area, near Takhini Hot Springs, where a surface water seep measures 46°C. The second well was drilled in winter 2018 in the Tintina fault system, near Ross River. Results to date suggest warm fluids and possible permeable rocks in the Takhini well between 450 and 500 m from surface, and a higher than average geothermal gradient of ~31°C/km in the Tintina Trench near Ross River. The results do not indicate temperatures for power generation at economic depths, however, they are encouraging enough to warrant further geothermal studies in southern Yukon.

This report was written and prepared by the Canadian Geothermal Energy Association. It was developed with support from the Canadian Northern Economic Development Agency, Yukon Energy, and the Government of Yukon's Department of Energy, Mines, and Resources, including the Yukon Geological Survey and the Energy Solutions Center.

In collaboration with the Yukon Geological Survey, the Geological Survey of Canada, and other project partners, Innovate Geothermal Ltd. performed an analysis of geoscience data in southwestern Yukon as part of an effort to better understand the potential for geothermal energy resources that, if present, could be utilized to help reduce fossil fuel use. The study area for this project is located in the vicinity of the Village of Haines Junction (Dakwäkäda) and lies between the Denali and Shakwak fault zones. The main aim of this project is to analyze and interpret a variety of pre-existing and newly acquired geological and geophysical datasets to evaluate where geothermal reservoirs may be present within the study area. A secondary aim is to propose favourable drilling locations, if warranted, for exploratory wells to collect information on subsurface temperature and permeability. The geoscience work accomplished here includes both 2D map interpretation as well as construction of a 3D geologic model that was guided by geophysical inversion modelling of gravity, magnetic and audio-magnetotelluric survey data. At a regional scale, multiple lines of evidence suggest that subsurface temperatures are above the crustal average. More importantly, a municipal water well drilled in 2002 in the Village of Haines Junction produce warm (~20 °C) water from a depth of ~350 m. This water well proves that at least one permeable sediment-hosted geothermal aquifer is present under Haines Junction. Additional geothermal aquifers within the pile of young sediment that sits atop the bedrock are likely present. However, due to a lack of deep drilling in the area, the exact location, temperature, thickness and permeability of such aquifers remains unknown. In this study, a depth-to-bedrock model has been generated to aid with the identification of favourable target areas for exploratory drilling of geothermal wells. The four areas where the top-of-bedrock is deepest have estimated depths in the range 650 to 1225 m below ground surface. Temperature data from two wells in the Haines Junction area suggests the temperature gradient is ~60 °C/km. Thus, geothermal aquifers located near the top-of-bedrock in the four areas identified could have temperatures in the range of 39–74 °C. Production of geothermal fluids from these areas requires permeability in the sediments that sit above the bedrock. Deeper drilling is needed to measure actual subsurface temperatures beneath the village and to identify permeable intervals. Geologic structures and faults that may control permeability in the bedrock remain poorly constrained.

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