Genesis of the Archaean Troilus Gold-Copper Deposit, Quebec. Evidence for a Multi-Stage, Mixed Genetic Origin
Abstract
The Troilus gold-copper deposit of Quebec is a past producing, low-grade, high-tonnage project hosted by Archaean volcano-plutonic sequences in the Frotet-Evans greenstone belt, Opatica Subprovince, Superior Province. A lack of consensus on the deposit genesis has presented problems for continued exploration. This work seeks to constrain a genetic model for the deposit by characterizing ore mineral assemblages and hydrothermal fluid signatures. A multi-technique approach consisting of petrography, laboratory and synchrotron X-ray fluorescence, electron probe microanalysis, microthermometry, and quantitative fluid inclusion gas analysis mass spectrometry were used in support of this work. Results indicate a complex deposit genesis consisting of at least four distinct hydrothermal events associated with synvolcanic and metamorphic metal endowments and remobilization separated in time by peak metamorphic conditions in the region. The diverse characteristics of the Troilus deposit suggest the superimposition of mineralization within a favourable geochemical and structural setting were key conditions for ore deposit development.