Isotope Ratio and Trace Elemental Imaging of Minerals by Secondary Ion Mass Spectometry

建议发展基于二次离子质谱仪(SIMS)的同位素比值成像技术，用于矿床的同位素微量分析。这一能力将与基于SIMS的微量元素微量分析相结合。矿床的成岩作用通常涉及一种水溶液，含矿组分通过水溶液输送。这些热液还能运输硫磺。不同的水过程产生不同的34S/32S同位素分馏。~(34)S/~(32)S比值可提供硫来源的重要指示，进而可提供经济上重要金属的来源。同位素比值和微量元素成像显示了不同矿物世代之间的相互关系。这些世代通常共存于单一的矿物颗粒中。PIS已经证明，成像SIMS可以成功地确定黄铁矿边缘中痕量金的位置(“看不见的”金)，并且可以对高度富含氢的陨石物质进行同位素比值成像。然而，推广到34S/32S同位素比值成像需要进一步的创新和许多仔细的测量。在第二阶段，这些成像技术将扩展到微分析年龄测定和微分析微量元素成岩。

This is a proposal to develop secondary ion mass spectrometry (SIMS) based imaging isotope ratio techniques for isotopic microanalysis of mineral deposits. This capability will be combined with SIMS based trace element microanalysis. The petrogenesis of ore deposits often involves an aqueous solution by which the ore-bearing components are transported. These hydrothermal solutions also transport sulfur. Different aqueous processes give rise to different 34S/32S isotope fractionations. The 34S/32S ratios can provide important indications of the sulfur origin, and by extension, the origin of economically important metals. Isotope ratio and trace element imaging show the interrelationships of different mineral generations. These generations often coexist within a single mineral grain. The PIs have demonstrated that imaging SIMS can successfully identify the location of trace gold levels ("invisible" gold) in pyrite rims, and that isotope ratio imaging of meteoritic materials highly enriched in deuterium is possible. However, extension to 34S/32S isotope ratio imaging requires further innovation and many careful measurements. In Phase II, these imaging techniques will be extended to microanalytical age dating and microanalytical trace element petrogenesis.