Tracing Volatiles Across Volcanic Arcs: I-129, He, N2, CH4 and CO2 in Fluids From New Zealand and Japan

该项目将使用新开发的方法比较三个电弧系统的挥发性通量，该方法将129 I系统与气体浓度和同位素系统学相结合。这些结果对于理解形成火山弧和影响海洋元素收支的俯冲过程具有重要意义。这一方法首次应用于最近完成的一个关于中美洲火山弧主火山区流体的项目，该项目表明海洋沉积物是主弧挥发物的主要来源，但弧前挥发物的历史却大不相同。当前项目的目的是在三个不同的弧上测试这些观测：新西兰北岛、日本南部和日本北方。选择这些位置是因为它们允许从前弧、主弧和后弧取样;相对简单;并且覆盖了俯冲板块的大年龄范围（日本南海海槽：20 Ma;新西兰Hikurangi海沟：90 Ma;日本海沟：130 Ma）。He、N2、CH 4和CO2的浓度和同位素组成将与129 I/I比值和卤素浓度一起确定。结果将深入了解火山弧中的元素通量，它们对俯冲沉积物和地壳的年龄和组成的依赖，并将提高我们对俯冲沉积物中有机物质的动员和再循环的理解。这项研究计划为期三年，将与日本和新西兰的专家合作进行。

FehnEAR-0229100The project will compare volatile fluxes across three arc systems using a newly developed approach that combines the 129I system with gas concentrations and isotopic systematics. The results are important for understanding subduction processes that form volcanic arcs and affect the element budget of the oceans. The approach was first applied in a recently finished project on fluids from the main volcanic zone in the Central American volcanic arc, where it was demonstrated that marine sediments are a major source of volatiles in the main arc, but that volatiles in the fore arc have a considerably different history. The purpose of the current project is to test these observations on three different arcs: North Island of New Zealand, southern Japan, and northern Japan. These locations where chosen because they allow sampling from a fore arc, main arc, and back arc; are relatively uncomplicated; and cover a large age range of subducting plates (Nankai Trough, Japan: 20 Ma; Hikurangi Trench, New Zealand: 90 Ma; Japan Trench: 130 Ma). Concentrations and isotopic compositions of He, N2, CH4 and CO2 will be determined together with 129I/I ratios and halogen concentrations. Results will give insights into element fluxes in volcanic arcs, their dependence on age and make-up of subducting sediments and crust, and will improve our understanding of mobilization and recycling of organic material from subducted sediments. The study is planned for three years, and will be carried out in collaboration with experts from Japan and New Zealand.