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TitleSurficial geochemical surveys over concealed uranium ore of the Phoenix and Millennium deposits in the Athabasca Basin, Saskatchewan
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AuthorHattori, K; Power, M; Chen, S; Krahenbil, A; Dudek, N; Sorba, C; Kotzer, T; Potter, E G
SourceTargeted Geoscience Initiative 4: unconformity-related uranium systems; by Potter, E G (ed.); Wright, D M (ed.); Geological Survey of Canada, Open File 7791, 2015 p. 32-42, https://doi.org/10.4095/295781 (Open Access)
Year2015
PublisherNatural Resources Canada
Documentopen file
Lang.English
Mediaon-line; digital
RelatedThis publication is contained in Potter, E G; Wright, D M; (2015). Targeted Geoscience Initiative 4: unconformity-related uranium systems, Geological Survey of Canada, Open File 7791
File formatpdf
ProvinceSaskatchewan
NTS74H
AreaMcArthur River; Key Lake
Lat/Long WENS-106.0000 -104.0000 58.0000 57.0000
Subjectseconomic geology; radioactive minerals; soils science; geochemistry; unconformity-type deposit; unconformities; uranium deposits; uranium; mineral deposits; mineral occurrences; mineralization; soil geochemistry; Athabasca Basin; Phoenix Deposit; Millennium Deposit
Illustrationslocation maps; cross-sections; photographs; histograms; plots
ProgramUranium Ore Systems, Targeted Geoscience Initiative (TGI-4)
Released2015 03 02 (08:30)
AbstractGeochemical surveys of surficial media (soil, water, and gas) have been conducted to evaluate and prioritize methods of detecting the presence of deeply-buried unconformity-related U deposits. The study selected two sites: the Phoenix and Millennium deposits in the eastern Athabasca Basin, Saskatchewan. The Phoenix deposits lie at a depth of ca. 400 m along the unconformity between Athabasca sandstones and the basement rocks, and the Millennium deposit at a depth of ca. 750 m along a major shear deformation zone in the basement. Humus and B-horizon soil samples show elevated metal contents including U directly above the ore bodies and WS Shear Zone at the Phoenix deposits, and broad areas over shear zones at the Millennium property. The elevated values of metals in the soil samples were reproduced in subsequent years of sampling in both properties. Laboratory leach experiments on humus using a variety of acids indicate that the elevated contents of metals are tightly held in organics, not adsorbed on the surface of clays or organic matter. Examination of sandstone geochemistry over the Phoenix deposits shows a chimney-like distribution of elevated metal contents from the deposits to the upper sandstones. The uppermost sandstones contain elevated metal contents, including U. Principal component analysis reveals high scores of elements associated with U, such as rare earth elements and Pb in the basal Read Formation and the uppermost Dunlop Member of the Manitou Falls Formation. The evidence suggests that metals were dispersed in the sandstones during hydrothermal alteration related to ore-formation but were recently dispersed into the surface media. The proposed interpretation is consistent with low 206Pb and 207Pb in humus samples and high contents of 222Rn in ground waters. With a half-life of 3.8 days, 222Rn cannot be transported from the deeply-seated ore to the surface in several days, and likely originated from U and/or 226Ra (direct parent of 222Rn) present in upper sandstones and soil. The concentrations of He are extremely high in groundwater close to the surface projection of the Millennium ore body and higher at deeper levels. The data appears to suggest upward diffusion of He from the U ore, but the distribution of high He in two study sites suggests its dispersion both vertically and laterally with groundwater flow. In summary, deeply-buried U deposits produce geochemical anomalies in surface media, but the expression of anomalies and media vary at different sites in response to local glacio-fluvial history, soil development and hydrological conditions.
GEOSCAN ID295781