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TitreParagenesis of the Centennial unconformity-related uranium deposit and the potential for igneous driven hydrothermal activity in the Athabasca Basin
AuteurReid, K D; Ansdell, K; Jiricka, D; Witt, G; Potter, E
SourceAssociation géologique du Canada-Association minéralogique du Canada, Réunion annuelle, Programme et résumés vol. 35, 2012 p. 116
Séries alt.Secteur des sciences de la Terre, Contribution externe 20120011
ÉditeurSociety for Geology Applied to Mineral Deposits (SGA)
RéunionGAC-MAC 2012; St.John's; CA; mai 27-29, 2012
Documentpublication en série
Mediapapier; en ligne; numérique
SNRC64E; 64L; 64M; 74E; 74F; 74G; 74H; 74I; 74J; 74K; 74L; 74M; 74N; 74O; 74P
Lat/Long OENS-112.0000 -102.0000 60.0000 57.0000
Sujetsparagenèse; uranium; gisements d'uranium; minéralisation; roches ignées; altération hydrothermale; système hydrothermal; Bassin d'Athabasca ; géologie économique; pétrologie ignée et métamorphique
ProgrammeUranium, GEM : La géocartographie de l'énergie et des minéraux
LiensOnline - En ligne
Résumé(disponible en anglais seulement)
The Centennial unconformity-related uranium deposit in the south-central Athabasca Basin has a complex paragenetic history which differs, in some aspects from similar deposits in the basin. The paragenetically earliest uraninite appears to be broadly coeval with the diagenetic illite-sudoitedravite-APS assemblage. However, the deposit is intruded by diabase, which is petrographically and chemically similar to the regionally extensive 1270 Ma Mackenzie dyke swarm. The dykes at the Centennial deposit provide a time constrain not observed at many other deposits in the basin. Clinochlore, euhedral quartz, carbonate and pyrite were precipitated after the diabase and overprint the earlier diagenetic assemblage. Chlorite geothermometry of the earlier sudoite indicates temperatures during diagenesis and mineralization likely reached 200°C whereas the later clinochlore formed at temperatures as high as 320°C probably due to additional heat provided by the intrusion. The latest alteration feature is the ubiquitous development of kaolinite along fractures and pervasively through the ore zone.
The paragenesis developed by other workers for the high-grade McArthur River unconformity-related uranium deposit and the 'apparently
barren' Wheeler River Zone K is very similar to that observed at Centennial with clinochlore, euhedral quartz, carbonate and sulphide
forming late relative to the diagenetic/primary mineralization assemblage. Fluid inclusions associated with late euhedral quartz at McArthur River reveal temperatures higher than those associated with diagenesis. Similarly, the composition of late clinochlore at Wheeler River indicates higher temperatures than the earlier developed diagenetic sudoite. Therefore, similar to Centennial, both areas record a period when temperatures were elevated after diagenesis and primary uranium deposition during the development of the later clinochlore, euhedral quartz, carbonate and sulphide assemblage. In addition, recrystallized uraninite and illite, and isotopically disturbed U-Pb and Ar-Ar systems at the two locations yield ages close to that of the Mackenzie dykes. These observations imply that hydrothermal activity initiated by igneous events, such as the Mackenzie dykes, may be more widespread in the basin, even where dykes are not directly observed. Future studies in the Athabasca Basin should recognize the possibility that igneous activity may have played an important role in developing some of the postmineralization alteration, including precipitation of sulfide minerals which, if formed around a uranium deposit may have aided in preservation.