ABSTRACT

Kurt Kyser contributed significantly to understanding the role that fluids play in the formation of unconformity-related U deposits in Canada and Australia and also in the exploration for these deposits. Kurt's exploration research was collaborative with industry, and arguably the most productive of the many industry-collaborative relationships Kurt developed was with Uravan Minerals, a junior exploration company. Ten years of collaborative U-deposit and exploration geochemical research with Uravan, including development of innovative multi-media surface sampling and analytical methods, culminated with the Stewardson Lake uranium exploration project in the Proterozoic Athabasca Basin, Canada. Soil clay separates, pine and spruce tree cores and vegetation, and glacially transported sandstone boulders collected at Stewardson Lake record 207Pb/206Pb ratios as low as 0.18, indicative of radioactive decay of U in a Proterozoic-aged U deposit, and elevated pathfinder elements such as Ni and Co in two areas of the Stewardson Lake property named Areas A and B. Four diamond drill holes in Areas A and B tested targets consisting of anomalous surface-media geochemistry coincident with conductive host rocks determined using geophysical methods. The favorable targeting characteristics were not explained by two of the drill holes in Area A, where only narrow intervals of elevated U, radiogenic Pb, and pathfinder elements or structural disruption that can accompany Athabasca U deposits were intersected. Two drill holes in Area B intersected a broad zone of characteristic chlorite + hematite + illite alteration and U concentrations >1 ppm (aqua regia) in the basal host sandstone. One drill hole in Area B intersected a ∼30-meter-thick hydrothermal alteration zone consisting of silicification, chlorite + kaolinite clay alteration, smoky quartz, Ni-Fe sulfides, and disseminated uraninite accompanied by elevated gamma count rates. Fractures in the host sandstone in Area B record the highest pathfinder concentrations and the most radiogenic Pb isotope ratios and were likely a conduit for secondary dispersion of alteration-related components to the surface. The results validate the Uravan/QFIR exploration model developed over a decade of collaborative applied research and confirm that the Stewardson Lake area is highly prospective to host unconformity-related U mineralization. Lastly, clay alteration mineralogy in the Stewardson Lake area is contrasted with that in the eastern Athabasca Basin, and the value of the industry–academic relationship that benefited both Uravan Minerals and Kurt's Queen's Facility for Isotope Research laboratory is discussed.

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