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TitreFe isotopic composition of alteration minerals from McArthur River Zone 4 Deposit, Athabasca Basin
TéléchargerTéléchargement (publication entière)
AuteurAcevedo, A; Kyser, T K
SourceTargeted Geoscience Initiative 4: unconformity-related uranium systems; par Potter, E G (éd.); Wright, D M (éd.); Commission géologique du Canada, Dossier public 7791, 2015 p. 61-73, (Accès ouvert)
ÉditeurRessources naturelles Canada
Documentdossier public
Mediaen ligne; numérique
Référence reliéeCette publication est contenue dans Potter, E G; Wright, D M; (2015). Targeted Geoscience Initiative 4: unconformity-related uranium systems, Commission géologique du Canada, Dossier public 7791
ProvinceAlberta; Saskatchewan
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
Sujetsgîte de type discordance; discordances; gisements d'uranium; uranium; gisements minéraux; gîtes minéralogiques; minéralisation; rapports isotopiques; isotopes; fer; argiles; Bassin d'Athabasca ; géologie économique; minéraux radioactifs
Illustrationslocation maps; photomicrographs; cross-sections; tables; histograms; plots
ProgrammeÉtude des gîtes d'uranium, Initiative géoscientifique ciblée (IGC-4)
Diffusé2015 03 02 (08:30)
Résumé(disponible en anglais seulement)
This study examines the Fe isotopic composition of alteration minerals from the McArthur River deposit Zone 4 and investigates the premise that Fe isotopic values can be used to indicate how and where uranium ore deposition occurred. Iron isotopic signatures can be used to discriminate areas where significant redox reactions have occurred and thus, may indicate areas fertile for uranium mineralization. Iron plays an important role as a reducing agent during the formation of U deposits, particularly Fe2+ as it is involved in reducing U as follows:
U6+ (aq) + 2Fe2+ (aq) + 2H2O ? U4+O2(uraninite) + 2Fe3+ (chlorite or hematite) + 4H+ (aq)
Under equilibrium conditions, aqueous Fe3+ species or minerals that contain Fe3+ have higher 56Fe/54Fe ratios than those with Fe3+ and Fe2+ oxidation states.
The d56FeIRMM-014 values in clay mineral separates from both sandstone and basement rocks near the McArthur River deposit have a range of nearly 1.5perthousand. The d56Fe values of clay separates, however, do not correlate with distance from the mineralization nor do they correlate with Fe3+/Fetotal, other isotopic systems such as O or Pb, or any element other than Mg. Instead, d56Fe values are more complex than the single redox reaction above and can be divided into three distinct populations: (1) values ranging from 0 to 0.5perthousand which represent background values for the McArthur River deposit, as reflected by early chlorite in basement rocks that occurs distal to faults and furthest from the system; (2) d56Fe values < 0perthousand reflecting post-ore fluid events in samples that are located near lithologic boundaries or faults, which are susceptible to overprinting by the mineralizing system or later fluids; and (3) d56Fe values >0.5perthousand resulting from the oxidation of Fe during reduction of U6+ as recorded in samples near the ore zone or in the sandstone directly above the extension of the P2 fault system. The ?56Fe values indicate that samples above the silicified zone and up to 300m from the ore zone were affected by the primary dispersion of the mineralizing system and that Fe was a reductant of U in the mineralizing process. Based on these results, Fe isotopes reveal for the first time, processes associated with redox reactions in ore deposits. The redox population also provides an indication on the fertility of an alteration system, particularly along ore-hosting faults.