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TitreCompositional variation and timing of aluminum phosphate-sulfate minerals along the P2 fault and in association with the McArthur River Deposit, Athabasca Basin, SK, Canada
AuteurAdlakha, E E; Hattori, K
SourceAmerican Mineralogist ., https://doi.org/10.2138/am-2015-5069
Séries alt.Secteur des sciences de la Terre, Contribution externe 20140242
Documentpublication en série
Lang.anglais
DOIhttps://doi.org/10.2138/am-2015-5069
Mediapapier
ProvinceAlberta; Saskatchewan
SNRC74E; 74F; 74G; 74H; 74I; 74J; 74K; 74L; 74M; 74N; 74O; 74P
Lat/Long OENS-112.0000 -104.0000 60.0000 57.0000
Sujetsgisements d'uranium; aluminium; roches sédimentaires métamorphosées; dépôts de remblayage des fractures; uranium; altération hydrothermale; diagenèse; altération; géochimie; sédimentologie
ProgrammeÉtude des gîtes d'uranium, Initiative géoscientifique ciblée (IGC-4)
Résumé(disponible en anglais seulement)
Aluminum phosphate-sulfate (APS) minerals in the metasedimentary rocks below the Athabasca Basin record geological events including paleoweathering, alteration by diagenetic fluids of the overlying Athabasca sandstones, and uranium mineralization. Here, we present the occurrence and compositions of APS minerals in metasedimentary rocks along: i) the P2 fault (7 km of its total 13 km strike length), ii) the Bleached Zone along the unconformity between Athabasca Group sandstones and the basement (250 m outside of the P2 fault), and iii) in the Green/ Red Zone paleoweathering profile in the footwall 100 m outside the P2 fault. The APS minerals are common along the P2 fault (the main mineralization-controlling fault of the McArthur River deposit), sparse along the unconformity and rare in the basement outside of the P2 fault zone. The chemical composition of APS minerals and associated clay-sized minerals are dependent on these locations: i) APS minerals along the P2 fault occur with sudoite (± illite, magnesiofoitite) and are zoned with Sr-, Ca- and S-rich cores (solid solution between svanbergite and crandallite) and LREE- and P-rich rims (close to florencite); ii) APS minerals of the Bleached Zone are Sr- and S-rich, close to the svanbergite composition, and occur with an assemblage of dickite, kaolinite and illite; and iii) APS minerals in the Green/ Red Zone occur with sudoite and clinochlore and are zoned with Ce- and As-rich cores (close to arsenoflorencite-(Ce)) and are rimmed by crandallite and svanbergite. The occurrence of svanbergite with dickite-kaolinite-illite of the Bleached Zone suggests formation by diagenetic fluids from the overlying sandstones. Arsenoflorencite-(Ce) likely formed during paleoweathering as it is rimmed by svanbergite of diagenetic origin and found in the paleo-weathering alteration profile. Although the McArthur River deposit strikes 1.7 km, APS minerals with similar composition (close to florencite) and co-existing with alteration assemblages similar to ore zone are found along the entire 7 km of the P2 fault, including non-mineralized areas of the fault. In addition, florencite-type APS minerals are absent beyons 50 m from the centre of the fault. Florencite-type APS minerals proximal to ore also contain appreciable U (up to 16 ppm), suggesting that oxidizing uraniferous fluids travelled along the entire P2 fault and crystallized florencite. Therefore, APS minerals can be excellent vectors when exploring for fertile structures that host uranium deposits.
Résumé(Résumé en langage clair et simple, non publié)
L¿Initiative géoscientifique ciblée (IGC-4) est un programme géoscientifique fédéral de collaboration qui fournit à l¿industrie les connaissances géoscientifiques et les techniques novatrices de prochaine génération dont elle a besoin pour mieux détecter les gîtes minéraux enfouis, réduisant ainsi certains risques liés à l¿exploration. Ce document porte sur les propriétés chimiques des minéraux de phosphate d'aluminium et de sulfate d'aluminium par rapport à l'altération hydrothermale le long d'une faille où se trouve le gisement d'uranium de McArthur River. Les résultats de cette étude confirment la validité des modèles génétiques actuels dans lesquels les fluides uranifères sont concentrés le long des corridors de faille, alors que la précipitation de l¿uranium était contrôlée par la présence de milieux réducteurs découlant des roches du socle.
GEOSCAN ID295313