Development of a magmatic-hydrothermal model for the genesis of platinum-group element (PGE) deposits in porphyry and epithermal settings in the Canadian Cordillera

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Porphyry and epithermal deposits, traditionally mined for Cu-Au-Mo-Ag, may host important resources of platinum-group elements (PGE; notably Pd and Pt). In Canada, the province of B.C. hosts porphyry deposits that contain zones that may potentially be classified as significant future PGE resources (~1-6 grams/ton of Pd; Ref. 1). Compared to deposits in traditional mafic-ultramafic settings, PGE-bearing porphyry and epithermal systems are economically and environmentally preferable to most known magmatic sulfide deposits because of the lower cost of mining by open pit methods, and the high acid-buffering potential of ores and wastes. With increasing pressure on Canadian industry and the public as energy consumers to meet emissions targets set in motion under the Copenhagen Accord (17% reduction from 2005 levels by 2020), there is a growing urgency for multi-million ounce supplies of PGE that will play a vital role in the production of catalysts, exchange membranes for hydrogen purification, fuel storage media and components for a variety of alternative energy technologies (wind, solar thermal, tidal). However, the overall success rate for PGE exploration is very low, and it is unlikely that an adequate long-term resource base from "traditional" settings in Canada will stabilize. In porphyry-epithermal settings, understanding of the origin of PGE is very poor and prevents cost-effective and successful discrimination between geological host environments that may or may not contain economic concentrations of the metals. The proposed study will increase our scientific knowledge of the origin of PGE deposits in atypical, non-traditional geological environments, and in general, will elucidate uncertainties about the geochemical and petrological processes active in orogenic belts that are responsible for the transfer ore metals from the mantle to the shallow crust. The research will also provide mining exploration companies in Canada and elsewhere with field-tested geological criteria to enable discrimination between PGE-barren and PGE-fertile arc terranes.