The Yukon Placer Mining Industry report reflects the strong relationship between the Yukon Geological Survey (YGS) and the Yukon placer mining industry. Our annual tours into the various gold fields are always productive and provide new details on placer gold settings, which this report encapsulates.

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.

The Yukon Placer Industry Report is a reflection of the strong working relationship between the Yukon Geological Survey (YGS) and the Yukon placer mining industry. Our annual tours into the various gold fields are always productive and provide new details on placer gold settings, which are encapsulated in this report.

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A regional till geochemistry project was completed in conjunction with bedrock mapping across rocks of Yukon-Tanana Terrane and North American affinity in central Yukon. The high mineral potential of the area is based on recent discoveries in the Finlayson Lake area to the southeast, an area thought to juxtapose the Glenlyon area prior to displacement on the Tintina Fault. The study area lies at the limit of the Late Wisconsinan McConnell glaciation. Ice flow was largely directed by topography. Soil profiles reveal a veneer of White River ash and loess over most till deposits. Geochemical results from 285 till samples highlight new anomalies in gold, gold/arsenic (intrusive- and fault-related), copper (veins), copper/nickel (ultramafic rocks) and zinc (sedimentary-exhalative (SEDEX) and epithermal). An orientation survey was completed at the Clear Lake SEDEX deposit to evaluate the extent of glacial dispersion down-ice from mineralization.

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 is the third in a series of five-year planning documents that have guided government geoscience in Yukon over the last ten years. It presents a broad set of needs and priorities for Yukon geoscience for the next five years, but is not a business or work plan. Although developed primarily from the Yukon Geological Survey (YGS) perspective, the Geological Survey of Canada and universities will help to meet these needs either independently or through partnerships with the YGS. It was developed during the spring, summer of 2004 as an internal draft that was later modified and refined through consultation with the Geological Survey of Canada and the Technical Liaison Committee to the YGS. Over the last five years, the need for geoscience information has grown and spread to a wider and wider audience. Geoscience is utilized primarily by the mining and petroleum sectors to support exploration for minerals and hydrocarbons, but it is increasingly playing a role in other industries such as forestry, fisheries and tourism. In all of these industries it is playing a role in their development and management. Decisions related to the utilization of natural resources are increasingly being made or influenced by many groups including developers, land managers planners, regulators, First Nations, and the general public. Their decisions need to be formed with accurate information about the nature and potential of resources, and the best practices in mitigating and preventing environmental damage. This volume includes sections on: bedrock mapping, mineral deposit studies, mineral assessments, regional geochemical and geophysical surveys, subsurface geology, energy/hydrocarbons, surficial geology and placer deposits, information management and outreach.

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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.

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