Geological characteristics and metallogenic model of the Cannington Ag-Pb-Zn deposit, Australia

The Cannington Ag-Pb-Zn deposit represents an important discovery of Ag-rich Broken Hill-type mineralization in the eastern segment of the Mount Isa inlier. Lithostratigraphic correlations of the host lithologies with other units in the eastern segment are unclear. Limited dating of probable stratigraphic equivalents has given an age of 1677±9Ma, which is basically coeval with host depositional ages for Pb-Zn-Ag mineralization at Mount Isa and Broken Hill. The orebodies are divided on the basis of late structural displacement of the zone into Northern and Southern zones. The Southern zone is the focus of current development, and its mineralization occurs as crudely stratabound massive sulfide lenses that display complex brittle and ductile disruption. Mineralization within the Cannington Southern zone is divided into five main economic lode horizons that comprise nine mineralization types. Dominant sulfides are galena and sphalerite, which show multiple generations and variable intergrowths. Extreme Ag enrichment is a consistent association of all mineralization types in the Cannington deposit, and is mainly related to argentiferous galena with freibergite inclusions. High levels of Sb, Cd, As, Cu, and F are also a feature of specific mineralization types. When in full production, Cannington will be one of the world's largest Ag producers. A genetic model is proposed that involves high-temperature metasomatic zone refining of a preexisting Fe-Ca-Mn-Pb-Zn-Ag-rich mineralized system.