Collaborative Research: CI Isotope Systematics of Back-Arc Spreading Systems: Insights into Geochecmical Cycling of Volatile Elements Between Crust, Hydrosphere and Mantle

这项研究支持两个机构的研究：马萨诸塞州的世界卫生组织和俄勒冈州立大学。这项工作包括开发技术和方案，在二次离子质谱仪上分析俯冲带火山岩中一种有希望的新示踪剂(氯稳定同位素)。氯稳定同位素被怀疑是火山流体的重要示踪物，这项研究使用来自各种火山玻璃的样本来检验这种可能性。该研究项目包括确定样品中可能影响分析精密度和准确度的基质和其他影响因素，并分析了一套12个样品，这些样品也已在热电离质谱仪上进行了测量和校准。这种重复使得能够定量地确定这一新的原位技术的准确性和精密度，并与标准质谱学获得的结果进行比较，以评估这些分析的可信度。其他样品，包括西太平洋刘盆地弧后扩张中心火山岩晶体中捕获的熔融包裹体中的玻璃，也将被检查。这些分析是第一次对火山玻璃中的熔体包裹体进行现场分析。广泛的影响这项工作的广泛影响是开发新的技术和方案，允许在二次离子质谱仪上分析氯稳定同位素。它还将支持世界卫生组织的分析基础设施，并促进美国两所大学和瑞典斯德哥尔摩的NORDSIM分析设施之间的合作。

This research supports researches at two institutions: WHOI in Massachusetts and Oregon State University. The work involves the development of techniques and protocols to analyze a promising new tracer (chlorine stable isotopes) of volcanic volatiles in subduction zone volcanic rocks on a secondary ion mass spectrometer. Chlorine stable isotopes are suspected to be important tracers of volcanic fluids and this study examines this possibility using samples from a variety of volcanic glasses. The research program includes the identification of matrix and other effects in the samples that can compromise analytical precision and accuracy of the method and analyzes a suite of twelve samples that have also been measured and calibrated on thermal ionization mass spectrometers. This duplication allows a quantitative determination of the accuracy and precision of this new in-situ technique and a comparison with results obtained by standard mass spectrometry to assess the level of confidence that can be placed on these analyses. Additional samples, that include glasses in melt inclusions trapped in crystals from volcanic rocks from back arc spreading centers in the Lau Basin in the western Pacific Ocean, will also be examined. The analyses represent the first time in-situ analyses have been made on melt inclusions in volcanic glasses.Broader ImpactsBroader impacts of this work are to develop new techniques and protocols to permit the analysis of chlorine stable isotopes on a secondary ion mass spectrometer. It will also support analytical infrastructure at WHOI as well as foster collaboration between two universities in the US and the NORDSIM analytical facility in Stockholm, Sweden.