The nature and origin of the Brucejack epithermal gold deposit, British Columbia

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Epithermal gold deposits host a significant portion of the world's known gold reserves and are responsible for a growing share of both global and Canadian gold production. Despite increased attention from the mining industry, discovery rates for new epithermal gold deposits have declined markedly since the late 1990s. Although many factors have influenced this decline, it is widely agreed that a better understanding of the conditions and processes controlling the formation of epithermal gold deposits is needed to help mining companies develop more successful exploration strategies. ** The Brucejack gold deposit in the Stewart-Eskay Creek mining district of northwestern British Columbia is host to a recently discovered, large and exceptionally high-grade (up to 41,000 g/ton Au) low- or intermediate-sulphidation epithermal deposit. Within the Valley of the Kings zone at Brucejack, exploration diamond drill holes have sampled long intervals of epithermal gold mineralisation in support of ongoing exploratory underground mining. Such advanced exploration of the deposit offers an unparalleled opportunity to investigate the source, physico-chemical conditions and processes governing the concentration of gold in epithermal ore-forming systems. ** This project aims to develop a genetic model for the Brucejack deposit by chemically (including isotopically) and petrographically characterising its ore mineralisation and associated hydrothermal alteration, determining the composition of its mineralising fluids through fluid inclusion analysis, reconstructing the physiochemical conditions that controlled gold mineralisation through thermodynamic analysis and quantitatively testing plausible models of ore formation. If successful, the project will improve on existing models for the genesis of epithermal gold deposits and the strategies that guide their exploration. Locally, it will also improve understanding of the genetic links between gold mineralisation at Brucejack and copper-gold mineralisation in adjacent world-class porphyry deposits in the Stewart-Eskay Creek mining district.****