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

FEHNEAR-0229100该项目将使用一种新开发的方法来比较三个电弧系统的挥发性通量，该方法将129I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并影响海洋元素收支的俯冲过程很重要。这一方法最初是在最近完成的一个关于中美洲火山弧主火山带流体的项目中应用的，在该项目中，证明海洋沉积物是主弧中挥发物的主要来源，但前弧中的挥发物具有相当不同的历史。目前项目的目的是在三个不同的弧线上测试这些观测结果：新西兰北岛、日本南部和日本北部。之所以选择这些地点，是因为它们允许从弧前、主弧和弧后取样；相对简单；覆盖了大范围的俯冲板块(日本南开海槽：20 Ma；新西兰Hikurangi海沟：90 Ma；日本海沟：130 Ma)。氦、氮、甲烷和二氧化碳的浓度和同位素组成将与129I/I比值和卤素浓度一起测定。这些结果将使我们深入了解火山弧中的元素通量及其对年龄和俯冲沉积物和地壳组成的依赖关系，并将加深我们对俯冲沉积物中有机质的活化和再循环的理解。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.