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 |
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Authors: | Jonathan Cloutier Kurt Kyser Gema R Olivo Dan Brisbin |
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Institution: | (1) Department of Geological Sciences and Geological Engineering, Queen’s University, Kingston, ON, K7L 3N6, Canada;(2) Cameco Corporation, 2121, 11th Street West, Saskatoon, SK, S7M 1J3, Canada |
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Abstract: | 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. |
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