Enigmatic massive sulphide mineralization in the High Arctic Large Igneous Province, Nunavut, Canada

Abstract

Modern mineral exploration strategies should take into account nontraditional metallogenic models for a given geological environment. Here we document the first detailed study of a massive sulphide showing associated with the High Arctic Large Igneous Province (HALIP) and Sverdrup Basin and in fact, only the second example of mineralization described from Axel Heiberg Island, Queen Elizabeth Islands, Canadian Arctic Archipelago. The Between Lake showing (western Axel Heiberg Island) is a small massive sulphide occurrence within scree/talus below a large ridge of gabbro. It was originally described by explorationists as an orthomagmatic sulphide occurrence hosted within a dioritic dyke. New petrographic and mineralogical analyses indicate that the showing consists predominantly of pyrrhotite with lesser pyrite, trace chalcopyrite, and rare sphalerite. No Ni- or Pb-bearing sulphide minerals were detected. Geochemically, the showing contains some Co and Cu, rare Zn, and generally very low Ni contents (<9 ppm). Sulphur isotope ratios of sulphide minerals range from +3.6 to + 6.6‰, somewhat heavier than expected for magmatic-derived S but isotopically lighter than S associated with local evaporite diapirs (+5.8‰ to +12.2‰). Orthomagmatic sulphides hosted in the diorite typically exhibit even lighter isotopic ratios of –3.9‰ to –1.00‰. The data are consistent with potential mafic–siliciclastic volcanogenic massive sulphide mineralization, or the like, the first documented in the HALIP. High heat flow associated with extensive HALIP magmatism was likely the driving force for such mineralization. Mineral prospectivity in Canada’s High Arctic had been predicated upon the potential presence of magmatic Ni – Cu – platinum group element sulphide mineralization. Rather than negating this potential, our findings provide evidence for additional metallogenic potential for this region of Nunavut.