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

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 mu m; 6-2 mu m; 2-0.6 mu m; 0.6-0.2 mu m; mu m) 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 c. 1000 Ma.