| Summary: | Platinum-group elements (PGE) are important precious metals and critical raw materials, but are some of the rarest metals in the Earth’s crust. The PGE are chalcophile elements and their distribution is largely controlled by the behaviour of sulphur (as sulphide) in magmatic environments. Mineralisation of PGE is most likely to occur in mafic and ultramafic intrusive systems and these share an inherent link with intraplate basaltic lavas produced by partial melting of the mantle, particularly associated with mantle plume thermal anomalies. In this thesis, new whole-rock geochemical data from a range of basaltic lavas from geologically-recent intraplate (i.e., mantle plume-related) settings are presented with a particular emphasis on examining chalcophile elements such as Ni, Cu, Co, Au and particularly, the PGE. Much of these data represent the first complete suites of major and trace elements, including PGE and Au analyses for key regions, such as Paraná, Etendeka, and Tenerife. The relationship between the PGE compositions of intraplate magmas and the mantle plumes responsible for their generation is interrogated using the combined application of quantitative geochemical melt modelling and a novel machine learning workflow, created for this project and featuring the PCA, t-SNE and k-means clustering techniques. Variations in melting processes due to different geodynamic conditions for each mantle plume studied dominates the controls on PGE abundances in magmas and thus lavas, as revealed by a quantitative account of partial melting of sulphide and silicate minerals in the mantle. In settings with deep, low degree partial melts (e.g., Canary Islands and Hawaii) chalcophile behaviour inhibits substantial source liberation from residual mantle sulphides. In settings with shallower, higher degree partial melts (e.g., Iceland and Kerguelen), chalcophiles are easily liberated from mantle sulphides. The most strongly PGE-enriched intraplate lavas are located at the edges of continents (e.g., East Paraná and East ...
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