Mineralogy and K-Ar geochronology of clay alteration associated with uranium mineralization in the Patterson Lake Corridor, Saskatchewan

Abstract: The Patterson Lake corridor (PLC) along the southwestern margin of the Athabasca Basin contains high-grade uranium deposits entirely within crystalline basement rocks. Visible-near infrared - shortwave infrared (VNIR-SWIR) spectroscopy measurements were collected on drill core samples from several locations in the PLC. The Triple R and Arrow deposits exhibit downhole spectral trends related to the crystallinity and thermal maturity of clays (illite and kaolinite) and mineralization. The K-Ar dates of silt-and-clay size fractions (10–6 µm; 6–2 µm; 2–0.6 µm; 0.6–0.2 µm; <0.2 µm) from five clay-altered samples decrease with grain size, and span 1608  ± 17 Ma to 1060  ± 14 Ma for the Spitfire discovery (n = 14) and 1342  ± 17 Ma to 289  ± 4.3 Ma for the Arrow deposit (n = 4). Alteration assemblages are broadly similar to Athabasca Basin basement-hosted deposits, and K-Ar dates indicate that high-grade uranium mineralization in the PLC reflects remobilization and concentration of primary ores. Integration of geochronology, clay mineralogy and VNIR-SWIR spectral parameters identify fertile fluid conduits when expanded to property- or corridor-scales, and provide additional evidence that ore grades of the Athabasca Basin deposits reflect several stages of hydrothermal mineralization spanning ~1000 Ma.