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TitreMultivariate statistical analysis of the REE-mineralization of the Maw Zone, Athabasca Basin, Canada
AuteurChen, S; Hattori, K; Grunsky, E C
SourceJournal of Geochemical Exploration vol. 161, 2016 p. 98-111,
Séries alt.Secteur des sciences de la Terre, Contribution externe 20160021
Documentpublication en série
Mediapapier; en ligne; numérique
Lat/Long OENS-106.0000 -104.0000 58.0000 57.0000
Sujetsassemblages de minéraux; terres rares; analyses de la roche, éléments de terres rares; uranium; gisements d'uranium; minéralisation; gisements minéraux; roches sédimentaires; grès; méthodes analytiques; analyses statistiques; statistiques de prospection minière; Formation de Manitou Falls ; Formation de Read ; Bassin d'Athabasca ; géomathématique; géologie économique; Précambrien
Illustrationslocation maps; plots; tables; photomicrographs
ProgrammeÉtude des gîtes d'uranium, Initiative géoscientifique ciblée (IGC-4)
Résumé(disponible en anglais seulement)
To evaluate the relationship between the enrichment of rare earth elements (REEs) and U, we carried out a principal component analysis (PCA) of sandstones in the REE-rich Maw Zone in the Athabasca Basin, Canada. The Maw Zone, a breccia pipe with surface exposure of 300 × 200 m, consists of highly silicified, hematitized, tourmaline-rich rocks with high REEs (up to 8.1 wt.% as total REE oxides). It is ~4 km southwest from the south end of the Phoenix U deposits, however, rocks in the Maw Zone do not show high U (b7.8 ppm in most rocks). We used RQ-mode PCA to compute variable and object loadings simultaneously, which allows the displays of observations and the variables at the same scale. PCA biplots of the Maw Zone data show that U is strongly correlatedwith V, Cr, Fe, Ni, Cu, Na, Li and Ba, but veryweakly correlatedwith heavy rare earth elements (HREEs)+Y, and inversely with light rare earth elements (LREEs) and P. Relative enrichment of HREEs, Y, and P suggests xenotime as the predominant host of the HREEs. The grouping of LREEs + Sr + Th + P suggests the probable occurrence of monazite and/or aluminum phosphate-sulfate (APS) minerals. A mineralogical study confirmed the common occurrence of xenotime and APS minerals. The positive association between U and Fe in the PCA plot in the Maw Zone suggests that U was transported by oxidized fluids. The absence of U mineralization in theMaw Zone is explained by lowU in the oxidizing fluids, or a lack reducing fluids to precipitate U. The PC1 and PC2may reflect themajor element assemblages related to the REE mineralization. The comparison of the maps of PC scores and the concentrations of HREEs+ Y and P shows that the scores of PCs are better indicating the hydrothermal REE mineralization. For prospecting HREEs, PC2 is more reliable than PC1 because PC2 has the largest variance of HREEs and the second largest variance of LREEs.