Classification and origin of vein-related Cu-Ag-Pb-Zn mineralization at Salkeld Lake, Nonacho Basin, Northwest Territories, Canada

Abstract

The Paleoproterozoic Nonacho Basin, Northwest Territories, Canada, contains a variety of poorly characterized mineral deposits, including hydrothermal Cu-Ag-(Pb-Zn) mineralization with one of the most representative examples at Salkeld Lake. The mineralization occurs in breccias, veins and disseminations within fracture networks and shear zones, cross-cutting granitic gneiss, metasedimentary rocks and alkali granitoids. Utilizing a variety of bulk and microanalytical methods, this study provides the first genetic constraints for, and a classification of, the mineralization at Salkeld Lake. The results of fluid inclusion and stable O isotope analyses of quartz and calcite suggest mixing, dilution and oxidation of a carbonic-aqueous mineralizing fluid by the introduction of cooler meteoric water, which led to metal precipitation. End-stage mineralizing conditions were at near surface P and T ~150-180 oC. The Cu-Ag-(Pb-Zn) mineralization formed at ~1831 ± 2 Ma (laser Ar-Ar of pre- to syn-mineralization muscovite) and is classified as an intrusion-related, sediment-hosted vein- and breccia related Cu-Ag-(Pb-Zn) deposit. Possible heat and metal sources are the calc-alkalic mafic Sparrow Dykes or related magmatic events, timed with the waning stages of Trans Hudson Orogen (~2.0-1.8 Ga).