Xenoliths in 2.7 Ga diamondiferous lamprophyres: a record of upper mantle compositions and metasomatism during orogeny

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This study will use upper mantle fragments, or xenoliths, from lamprophyres associated with the world's oldest in situ diamond deposits to investigate the formation of the 2.7 Ga lithosphere. The xenoliths were permeated by hydrous fluids prior to emplacement and therefore are a window into both the composition of the upper mantle and the nature of metasomatic processes during orogeny. The volatile-rich lamprophyres were emplaced at the same time as nearby gold deposits. Understanding the origin and distribution of deep fluid plumbing systems recorded in the xenoliths will resolve the mechanisms responsible for gold mineralisation and will provide an improved understanding of the links between tectonics and metasomatism. These results will have significant implications for the development of ore deposit models and will potentially lead to new discoveries.