Volatiles in Tonga Arc Magmas

摘要(0526450)普朗克智力价值岩浆中最重要的化学物种之一，水，影响着与俯冲带火山作用有关的一系列科学和社会问题。水不仅对俯冲和喷发的物理过程至关重要，而且对导致地幔熔融和岩浆产生的过程也至关重要。该项目旨在开展对汤加弧岩浆挥发分(H2O、CO2、SO2、Cl、F)含量的首次全面研究，或检验关于以下假设的假设：(1)板条流体的组成，(2)它们在地幔中的分布，以及(3)它们对熔融的影响。汤加弧提供了几个明确的假设测试，涉及世界上最高的构造板块会聚速度、异常高的地幔温度和200多公里的交叉走向成分变化，其中包括刘盆地的火山活动。这个项目通过使用离子和电子微探针测量熔体包裹体中的挥发性浓度来解决熔融和地幔组成的问题。这些数据将与电子探针和激光ICPMS的主量元素和微量元素组成相结合。数据将被用来建立板坯流体成分和地幔熔融过程之间的定量关系。样本目前来自澳大利亚组织支持的最近的研究邮轮，持续覆盖1000公里长、主要是海底的汤加弧。更广泛的影响这个项目补充了NSF-GEO中其他主要活动的科学计划，包括刘盆地的Ridge 2000和边缘俯冲工厂实验。一项重要成果将是来自汤加弧区的全面斑晶数据集，这在目前的在线数据库中没有得到很好的反映。该项目利用了澳大利亚来源的基础设施和运输时间成本。该项目的成果将被纳入波士顿大学的本科生和研究生课堂，并将支持一名女性研究生的博士论文和一名高级女性教职员工在马萨诸塞州波士顿大学的新研究方向。

ABSTRACT (0526450) PlankIntellectual MeritOne of the most important chemical species in magmas, H2O, affects a host of scientific and societal problems related to volcanism at subduction zones. Water is critical not only to the physics of subduction and eruption, but also to the processes that lead to melting and magma production in the mantle. This project seeks to develop the first comprehensive study of the volatile content (H2O, CO2, SO2, Cl, F) of Tonga arc magmas, or order to test the hypotheses regarding: (1) the composition of slab fluids, (2) their distribution in the mantle, and (3) their effect on melting. The Tonga arc provides several well-defined tests of hypotheses relating to the highest tectonic plate convergence rate in the world, anomalously high mantle temperatures, and cross-strike compositional variations along more than 200 km, which includes volcanism in the Lau Basin. This project addresses questions of melting and mantle composition by measuring volatile concentrations in melt inclusions using both ion and electron microprobes. These data will be combined with major and trace element compositions from electron microprobe and laser-ICPMS. Data will be used to develop quantitative relationships between slab fluid compositions and mantle melting progress. Samples are currently in-hand from recent research cruises supported by Australian organizations, with continuous coverage of the 1000 km long, largely submarine Tonga arc. Broader ImpactsThis project complements the science plans of other major initiatives in NSF-GEO, including RIDGE 2000 in the Lau Basin, and the MARGINS Subduction Factory experiment. One important outcome will be a comprehensive phenocryst dataset from the Tonga arc area, which is poorly represented in current on-line databases. This project leverages infrastructure and ship-time costs contributed from Australian sources. Results from this project will be incorporated into the undergraduate and graduate classrooms at Boston University, and will support the Ph.D. thesis of a female graduate student and a new research direction for a senior female faculty members at Boston University in Massachusetts.