Grant: Discovery Grants Program - Individual

Platinum-group element (PGE; Os, Ir, Ru, Rh, Pt, Pd) geochemistry plays a central role in the investigation of numerous first order geological problems, including chemical evolution of the terrestrial mantle, early Earth accretion and the formation of precious- and base-metal mineralization. In precious metal ore deposits and in rocks typical of the Earth's crust and mantle, platinum-group minerals (PGM) exert a major control on the composition and distribution of the PGE. Linking PGE signatures to the PGM inventory of rocks is a crucial step when interpreting the geochemical data but is significantly hampered by gaps in our understanding of the conditions of PGM crystallization. The latter, in turn, is partly a consequence of the very fine (nm-µm) grainsizes of the PGM in most rocks, including ore deposits. The overarching long-term goal of my research program is therefore to drive a step-change in understanding the controls on PGM crystallization in magmatic environments. My proposal is underpinned by four sub-projects, together directed at addressing three scientific objectives that focus on understanding the conditions and timing of PGM formation in magmatic ores, as well as constraining the extent to which they influence isotopic signatures in terrestrial and extraterrestrial materials. A new laboratory at uOttawa housing state-of-the-art equipment for visualizing and separating the PGM will be operational by mid-late 2023 and will provide a stimulating and inclusive environment for my students to work in. Coupled with the excellent electron microscopy facilities at uOttawa, my students will be able to establish excellent petrological sample context before applying novel PGE abundance/isotopic and heavy halogen measurement techniques. For the latter, all students will have opportunities to exploit my existing collaborative relationships and work with world-leading scientists in internationally renowned laboratories, providing them with formative experiences and training on advanced geochemical instrumentation. The proposed research will break new ground in establishing links between PGE geochemistry and PGM in geological materials, leading to a transformative change in the use of the PGM as petrogenetic indicators for high-temperature (magmatic) environments. As well as academia, project outcomes will have impact and relevance for the mining industries involved in producing these critical metals, particularly with respect to beneficiation of PGE ores and recovery of secondary metal from tailings piles, as well as exploration for new deposits. For example, this project will lead to a much deeper understanding of PGM relationships with other silicate, oxide and sulfide phases in ore bodies; essential knowledge for effective beneficiation. In relation to exploration, elucidating heavy halogen behavior during sulfide crystallization will pave the way for these elements to be used as pathfinder tools for PGM in and around sulfide ore deposits.