Geochemical, isotopic, and geochronlologic constraints on the formation of the Eagle Point basement-hosted uranium deposit, Athabasca Basin, Saskatchewan, Canada and recent remobilization of primary uraninite in secondary structures
Cloutier, J and Kyser, K and Olivo, GR and Brisbin, D, Geochemical, isotopic, and geochronlologic constraints on the formation of the Eagle Point basement-hosted uranium deposit, Athabasca Basin, Saskatchewan, Canada and recent remobilization of primary uraninite in secondary structures, Mineralium Deposita, 46, (1) pp. 35-56. ISSN 0026-4598 (2011) [Refereed Article]
The Athabasca Basin hosts many world-class unconformity-related uranium deposits. Recently, uranium reserves for the Eagle Point basement-hosted deposit have increased with the discovery of new mineralized zones within secondary structures. A paragenetic study of Eagle Point reveals the presence of three temporally distinct alteration stages: a pre-Athabasca alteration, a main alteration and mineralization comprised of three substages, and a post-main alteration and mineralization stage that culminated in remobilization of uraninite from primary to secondary structures. The pre-Athabasca alteration stage consists of minor amounts of clinochlore, followed by dolomite and calcite alteration in the hanging wall of major fault zones and kaolinitization of plagioclase and K-feldspar caused by surface weathering. The main alteration and uranium mineralization stage is related to three temporally distinct substages, all of which were produced by isotopically similar fluids. A major early alteration substage characterized by muscovite alteration and by precipitation Ca-Sr-LREE-rich aluminum phosphate-sulfate minerals, both from basinal fluids at temperatures around 240°C prior to 1,600 Ma. The mineralization substage involved uraninite and hematite precipitated in primary structures. The late alteration substage consists of dravite, uranophane-beta veins, calcite veins, and sudoite alteration from Mg-Ca-rich chemically modified basinal fluids with temperatures around 180°C. The post-main alteration and mineralization stage is characterized by remobilization of main stage uraninite from primary to secondary structures at a minimum age of ca. 535 Ma. U-Pb resetting events recorded on primary and remobilized uraninites are coincident with fluid flow induced by distal orogenies, remobilizing radiogenic Pb to a distance of at least 225 m above the mineralized zones.
basement-hosted, Eagle Point, geochemistry, geochronology, secondary uraninite, unconformity-related uranium deposit, fault zone, geochemistry, geochronology, mineral alteration, mineral deposit, mineralization, uraninite, uranium, Athabasca Basin