Volatiles in Tonga Arc Magmas

水是岩浆中最重要的化学物质之一，它影响着与俯冲带火山活动有关的许多科学和社会问题。 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。 该项目旨在对汤加弧岩浆的挥发性成分（H2O、CO2、SO2、Cl、F）进行首次全面研究，或检验有关以下方面的假设：（1）板状流体的成分，（2）它们在地幔中的分布，（3）它们对熔融的影响。 汤加岛弧提供了几个定义明确的假设测试有关的最高构造板块收敛速度在世界上，异常高的地幔温度，和跨走向成分变化沿着超过200公里，其中包括在劳盆地的火山活动。 该项目通过使用离子和电子微探针测量熔融包裹体中的挥发分浓度来解决熔融和地幔成分的问题。 这些数据将与电子探针和激光ICPMS的主要和微量元素组成相结合。 数据将被用来建立板片流体成分和地幔熔融过程之间的定量关系。目前已从澳大利亚组织支助的最近的研究航行中取得了样本，这些研究航行持续覆盖了1 000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国家科学基金会地球观测组织的其他主要倡议的科学计划，包括劳盆地的RIDGE 2000和MARGINS俯冲工厂实验。一个重要的成果将是一个全面的斑晶数据集从汤加弧区，这是在目前的在线数据库中表现不佳。该项目利用澳大利亚提供的基础设施和运输时间费用。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，并将支持博士学位。一名女研究生的论文和马萨诸塞州波士顿大学一名高级女教员的新研究方向。

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.