An evaluation of hydrocarbon resource potential in Eagle Plain is one aspect of the Yukon Sedimentary Basins Project, a five-year (2008-2013), collaborative Geo-Mapping for Energy and Minerals (GEM) Program of the Geological Survey of Canada (GSC), in partnership with the territorial governments and universities. As part of this project, Yukon Geological Survey (YGS) and Northern Cross (Yukon) Limited (NCY) are collaborating with the GSC to assess shale gas potential of Devonian shale at Eagle Plain. Diamond drill core was retrieved from mineral exploration properties to evaluate shale gas potential of Devonian shale of Road River Group and Canol and Imperial formations. Diamond drill core from four holes, located on the Rich property east of Eagle Plain Hotel, were examined and sampled. The core was systematically sampled and analysed by Rock-Eval pyrolysis, optical microscopy, X-ray diffraction (XRD) mineralogy, and palynology. The results indicate that the succession is thermally overmature with respect to hydrocarbon generation. Due to the high levels of thermal maturity, the Rock-Eval data are unreliable. However, high amounts of residual organic carbon suggest that the Canol Formation has the potential to be an important source rock in the region, under favourable burial conditions. The very high level of thermal maturity of the strata also resulted in very few identifiable Palynomorphs; however, Canol and Imperial formation samples yielded dates of Middle to Late Devonian and Frasnian to Famennian, respectively. XRD analyses indicate Canol Formation shale is highly siliceous whereas Road River Group shale and silty shale of the Imperial Formation are less siliceous and exhibit a more varied lithology. This study suggests that the Canol Formation is more prospective for shale gas than strata of the Imperial Formation or Road River Group.

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In collaboration with the Yukon Geological Survey, Innovate Geothermal Ltd. performed a multi-component geoscientific investigation in southwestern Yukon to initiate the search for subsurface geothermal energy resources that could be used for direct use applications and, possibly, the generation of electricity. The study area for this project is located near the community of Burwash Landing and straddles the eastern Denali fault zone. The aim of this project is to analyze and interpret a variety of pre-existing and newly-acquired geological and geophysical data sets to identify favourable subsurface targets for a shallow, exploratory geothermal drilling program that could take place in the future. The geoscience work accomplished here includes both 2D map interpretation as well as construction of a 3D geologic model that was tested by geophysical inversion modelling of gravity and magnetic survey data. In addition, a literature review was conducted to identify analogous geothermal structural environments located in similar crustal-scale transform fault zones for comparison with geothermal systems that may be present in the vicinity of the Denali fault. Importantly, geophysical data from this study discovered a right-step in the Denali fault that has the appropriate orientation to form a small pull-apart zone in the Earth’s crust within the project area south of Duke River. Such crustal extension may generate fractures and permeability in rocks in the subsurface. Subsurface permeability in geothermal systems provides the pathway for hot geothermal fluids to ascend to drillable depths. This study has identified seven drilling targets, all located in the vicinity of the previously mentioned right-step in the Denali fault. The 3D geologic model generated for this study was utilized to help understand the lithologic domains and structures likely to be encountered by the proposed exploratory boreholes. The distribution of temperature in the subsurface, however, remains a significant unknown. Regional-scale, Curie point depth estimates suggest an average geothermal gradient of ~40°C/km near the eastern Denali fault, but drilling is required to measure actual subsurface temperatures. Based upon the encouraging results of this study, it is recommended that at least two of the seven targets are drilled to depths of 500–1000 m to obtain data on subsurface temperatures, fluids and geology.

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New mineral discoveries in the Dawson Range have been heavily supported by soil geochemistry. The use of soil augers to penetrate through loess-rich units and into locally derived weathered bedrock has been important in the successful application of this technique. To assist the mineral exploration industry, we characterized the surficial geology, soils and permafrost of the northern Dawson Range. Mapping indicated that widespread loess is present in the study area and the thickest deposits are located in basins on the south side of the Dawson Range near the Donjek and White rivers. A mantle of weathered bedrock covers virtually the entire landscape. The texture of fluvial deposits is affected by stream order and base level changes along the Yukon River. By understanding the effects of slope, aspect, elevation and permafrost processes on surficial materials, a landscape model can be developed that will facilitate geochemical exploration and mineral development in the region.

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.

Results of surficial geology investigations in Wellesley basin and the Nisling Range can be summarized into four main highlights, which have implications for exploration, development and infrastructure in the region: 1) in contrast to previous glacial-limit mapping for the St. Elias Mountains lobe, no evidence for the late Pliocene/early Pleistocene pre-Reid glacial limits was found in the study area; 2) placer potential was identified along the Reid glacial limit where a significant drainage diversion occurred for Grayling Creek; 3) widespread permafrost was encountered in the study area including near-continuous veneers of sheet-wash; and 4) a monitoring program was initiated at a recently active landslide which has potential to develop into a catastrophic failure that could damage the White River bridge on the Alaska Highway.

This is a product of the Gold and base metals–southeastern Yukon (Selwyn basin) project funded jointly by the Geo-mapping for Energy and Minerals (GEM) program of Natural Resources Canada, and the Yukon Geological Survey (Government of Yukon).

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