Tracing Early Earth Evolution

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This research program proposes to use precious metals and their radiogenic isotopes to address some of the most long-standing and controversial issues in solid Earth geochemistry. The formation of the Earth's core should have left an irreversible imprint on the chemistry of the rest of the Earth. Yet many precious metals, such as the platinum group elements (PGEs), remain "over-abundant" in the mantle if core-formation was the sole control on its evolution. This indicates that the mantle was re-enriched at some point soon after its formation. New research has revealed hints of a temporal enrichment in PGEs that peaked almost 2 billion years after core formation. I plan a detailed investigation into the timing and nature of this re-enrichment, using magmatic rocks in Arctic Canada's ancient "greenstone belts". Understanding the early evolution of the Earth's mantle has fundamental implications for our knowledge of how the Earth evolved chemically and physically, from its initial accretion, to today. The uniquely fresh nature of some of the volcanic rocks allow investigation of geochemical changes in this critical period of Earth history, Many important precious metal deposits were generated in the earliest phases of Earth history, within the Archean eon (3.8 and 2.5 Ga) and so understanding how PGE abundances may have changed with time in the mantle has an important bearing on the origin of Archean precious metal deposits. Moreover, greenstone belts are host to major base-metal, gold and PGE deposits in Canada and globally, hence understanding their genesis and time of eruption is crucial for mineral exploration. The research program will provide training in state-of-the-art geochemical techniques that have applications in several high-tech industries and will train HQP in Arctic geology and field techniques . The research builds on my international reputation, established in the UK, for leadership in platinum group element and Os isotope research applied to diverse geological and biochemical/pharmacological problems. The techniques to be established for this research program do not yet exist in Canada and so will enhance Canada's reputation as a leader in the field of solid-Earth geochemistry.