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

PIS建议完成对大洋中脊玄武岩玻璃中PGe(Os、Ir、Ru、Pt和Pd)和与Re、S、Se、Te以及Ag和Cd有关的地球化学性质的记录和研究。重点将放在它们相对于相互作用的地幔热柱和相对分馏模式的系统空间变化上。到目前为止，由于各种问题，文献报道的MORB中PGE含量非常有限。然而，最近使用高分辨率、高灵敏度、电感耦合等离子体质谱(HR-ICP-MS)的同位素稀释分析，结合使用高压阿舍尔消解样品并与浓缩的PGE同位素尖峰进行平衡，现在已经克服了大多数问题。私人投资机构开发了一种HR-ICP-MS同位素稀释法来分析这些元素，他们现在建议将这种方法扩大到也包括Os。他们还建立了可靠的氢化物发生-电感耦合等离子体质谱同位素稀释法分析Se和Te，以研究S、Se和Te在同一玻璃上的分馏。众所周知，硫化物是PGE的重要宿主，可能在控制PGE在地球上的分布及其相对分馏方面发挥关键作用。

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.