Evaluation of primary and secondary geological processes at the Flin Flon CuZn deposit, Manitoba and Saskatchewan, Canada, using factor-vector analysis of ore geochemistry

Abstract

The Flin Flon volcanogenic CuZn deposit consists of massive and disseminated ores within Amisk volcanic strata of the Precambrian Shield. During the Hudsonian Orogeny the ores and their enclosing rocks underwent regional metamorphism, dynamic metamorphism, and contact metamorphism by post-Amisk intrusions. Using two sets of geochemical data, the nature of underlying causal influences on the geochemistry of the ores are tested by computer-processed varimax R-mode factor-vector analysis with computed factor scores. The first set of data comprises the analyses of 80 massive and disseminated ore samples made during the present study, for Fe, Cu, Zn, Pb, Mn, Cd, Ni, Co, Te, Sb, Bi, Ag, Au, and insoluble residue. Factor-vector analysis of the data shows three distinct associations of the metals in the ores, namely: FeCuTeNi, ZuPbCdSbCo, and AuAgBi. These associations are consistent with a mineralogical zoning, which has been interpreted as primary on strictly geological grounds, and shows a relative enrichment in sphalerite, galena, tetrahedrite and electrum over chalcopyrite toward the stratigraphic hanging wall. Mn and insoluble residue are the integral parts of the silicate matrix in the ores, as suggested by their inverse proportionality in concentration to the ore metals. The analysis confirms a trend to relative enrichment of FeCuTeNi, and depletion of ZnCdPbSbCo in the ores as a result, respectively, of contact metamorphism and dynamic metamorphism. The second set of data consists of mine analyses taken as average grades of Au, Ag, Cu and Zn for each of 92 assay crosscuts selected over the entire massive ore zone. Factorvector analysis of this data emphasizes a close association of Zn with AgAu in the massive ore. The amount of Cu increases with respect to Zn, Ag and Au with increasing depth in the mine, an effect attributable to dynamic metamorphism.