Comprehensive Study of the Platinum-Group Elements (PGE), and S, Se, and Te in Normal and Hotspot Affected Mid-Ocean Ridge Basalts

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The PIs propose to complete the documentation and study of PGE (Os, Ir, Ru, Pt and Pd) and geochemically related Re, S, Se, Te, as well as Ag and Cd in mid-ocean ridge basalt (MORB) glasses from the URI dredged rock collection. The emphasis will be on their systematic spatial variations relative to interactive mantle plumes and relative fractionation patterns. So far, PGE contents in MORB reported in the literature have been very limited due to a variety of problems. However, the recent use of isotope dilution analyses with high resolution, high sensitivity, inductively coupled plasma-mass spectrometry (HR-ICP-MS) combined with the use of the high pressure asher for sample digestion and equilibration with enriched PGE isotope spikes have now overcome most of these problems. The PIs have developed a HR-ICP-MS isotope dilution method for analyzing these elements, which they now propose to extend to include Os as well. They have also implemented a reliable Hydride Generation, HR-ICP- MS isotope dilution method for analyzing Se and Te, for the purpose of studying the fractionation of S, Se and Te on the same glasses. It is well known that sulphides are important hosts of the PGE and may play key roles in controlling the distribution of PGE and their relative fractionation in the Earth.