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TitreSurficial geochemical surveys over concealed uranium ore of the Phoenix and Millennium deposits in the Athabasca Basin, Saskatchewan
TéléchargerTéléchargement (publication entière)
AuteurHattori, K; Power, M; Chen, S; Krahenbil, A; Dudek, N; Sorba, C; Kotzer, T; Potter, E G
SourceTargeted Geoscience Initiative 4: unconformity-related uranium systems; par Potter, E G (éd.); Wright, D M (éd.); Commission géologique du Canada, Dossier public 7791, 2015 p. 32-42,
ÉditeurRessources naturelles Canada
Documentdossier public
Mediaen ligne; numérique
Référence reliéeCette publication est contenue dans Potter, E G; Wright, D M; (2015). Targeted Geoscience Initiative 4: unconformity-related uranium systems, Commission géologique du Canada, Dossier public 7791
Lat/Long OENS-106.0000 -104.0000 58.0000 57.0000
Sujetsgîte de type discordance; discordances; gisements d'uranium; uranium; gisements minéraux; gîtes minéralogiques; minéralisation; géochimie du sol; Bassin d'Athabasca ; géologie économique; minéraux radioactifs; pédologie; géochimie
Illustrationslocation maps; cross-sections; photographs; histograms; plots
Bibliothèque de Ressources naturelles Canada - Ottawa (Sciences de la Terre)
ProgrammeÉtude des gîtes d'uranium, Initiative géoscientifique ciblée (IGC-4)
Diffusé2015 03 02 (08:30)
Résumé(disponible en anglais seulement)
Geochemical 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.