The application of platinum group elements in komatiite-hosted nickel sulfide exploration

[Truncated abstract] Exploration for komatiite-hosted nickel (Ni) deposits is a continued challenge, due to small target size, discontinous nature, and lack of an alteration halo associated with the ore forming process. New komatiite-hosted Nil deposits are becoming increasingly difficult to locate, as the remaining prospective areas are typically under cover and at greater depths. Lithogeochemistry has the capacity to increase the target size beyond the physical mineralization and indicate whether the system is prospective to host mineralization. The potential use of the chalcophile elements, specifically the platinum group elements (PGE: iridium, rhodium, ruthenium, platinum, and palladium), as lithogeochemical prospectivity indictors is widely recognized, since the chalcophile elements are intimately associated with Ni ore formation process. The ore formation in komatiites is a consequence of sulfur saturation and the strong partitioning of the chalcophile elements from the silicate magma into the sulfide phase. During these processes, two mineralization signatures develop: chalcophile element enrichment and chalcophile element depletion. As such, chalcophile elements are used as prospectivity indicators. Previous applications utilizing the chalcophile elements as prospectivity (mineralization) indicators were limited, as the size of the ore forming system remained unconstrained. This limitation prevented the transformation of these prospectivity indicators into lithogeochemical vectors to Ni mineralization. This research identified two scale (size) components critical to the development of a Ni mineralization vector: 1) chalcophile element signature magnitude (relative enrichment and depletion): and 2) the spatial correlation (distance) between chalcophile element signatures and known Ni mineralization. These scale components of mineralized komatiite Ni systems are addressed through the investigation of three komatiite-hosted Ni sulphide areas.