Oxygen Isotope Studies of the Sources of Basaltic Volcanism: A Reevaluation Using Laser Fluorination of Phenocrysts

9628142斯托尔伯氧同位素比值可以对玄武岩熔岩地幔源区化学和同位素不均一性的来源提供重要的制约。全岩样品和玻璃的常规测量通常受到岩浆过程中样品蚀变和同位素分馏效应的显著影响。P.I.建议使用激光氟化技术对弧形熔岩中斑晶(主要是橄榄石)中的氧同位素变化进行全面调查。到目前为止的结果表明，激光氟化技术为分析橄榄石和其他斑晶中的18O/16O比值提供了一种准确和精确的手段。这项工作将包括对与弧有关的熔岩进行调查，重点是玄武岩弧后熔岩，这些熔岩可以提供俯冲带上方地幔“楔形”的信息。

9628142 Stolper Oxygen isotope ratios can provide important constraint on the origins of chemical and isotopic heterogeneity in the mantle sources of basaltic lavas. Conventional measurements of whole-rock specimens and glasses are typically significantly influenced by the effect of sample alteration and isotopic fractionation during magmatic processes. The P.I.s propose to use laser fluorination techniques to undertake a comprehensive survey of oxygen isotope variations in phenocrysts (primarily olivine) from arc-related lavas. Results thus far indicate that laser fluorination technique provides an accurate and precise means of analyzing 18O/16O ratios in olivine and other phenocrysts. The work will involve a survey of arc-related lavas, emphasizing basaltic back-arc lavas that can provide information on the mantle "wedge" above subduction zones.