Serpentinization Effects on Forearc Peridotite: Mineralogic, Textural, and Geophysical Study

摘要0752322 （Fryer）学术价值：本研究通过地球化学指标确定俯冲板块的流体通量以及俯冲对上覆板块地幔施加的应力，解决了水在会聚板块边缘中的作用这一基本问题。从马里亚纳前弧的蛇纹岩泥火山喷发的地幔物质样本将从距离海沟15至90公里的地点和沿走向约720公里的地点进行检查。岩石的矿物学和结构将被定量地检查，以确定弧前地幔应力制度的历史和演变。中红外光谱（MIR）将用于确定粗矿物百分比，并通过岩石学验证数据。微拉曼测绘将用于确定详细的矿物学。电子反向散射衍射将给出橄榄石颗粒的取向（显微结构反映弧前地幔的应力模式）。然后将选定的样品进行地震速度测量，以将结构各向异性和蛇纹石化程度与地震场测量结果联系起来。本研究提供了第一个完整的关于自然样品蛇纹石化和弧前地幔应变演化影响的区域数据集。这些数据将有助于更好地解释地球物理野外数据和对俯冲带地震活动的控制。MIR数据加上详细的岩石学和结构分析将能够更准确地分析实地样品和解释遥感数据。更广泛的影响：本研究对大型俯冲带断层研究具有广泛的意义，例如对圣安德烈亚斯和卡尔弗特断层的研究。它将在美国、日本和加拿大培训研究生和本科生。这项工作通过涉及三个机构的多学科研究，加强了研究和教育的基础设施。它还支持两名女性pi，她们都在EPSCoR机构（夏威夷大学）工作。调查结果将在互联网和CD上公布，供K-12学生、本科生和公众接受非正规和正规教育。该项目将加强nsf在马里亚纳地区资助的margins支持的工作，以及在马里亚纳前弧的ODP/IODP钻探。

ABSTRACT 0752322 (Fryer)Intellectual Merit: This research addresses fundamental questions of the role of water in convergent plate margins requires by using geochemical indicators to determine the flux of fluids from a subducting plate and the stresses imposed by subduction affect the overriding plate's mantle. Samples mantle material erupted from serpentinite mud volcanoes on the Mariana forearc will be examined from sites 15 to 90 km from the trench and up to ~720 km along strike. Mineralogy and textures of the rocks will be examined quantitatively to determine the history and evolution of stress regimes in the forearc mantle. Middle-infrared (MIR) spectroscopy will be used to determine rough mineral percentages, with the data being verified by petrography. Micro-Raman mapping will be used to determine for detailed mineralogy. Electron backscatter diffraction will give orientation of olivine grains (microtextures reflect stress patterns in the forearc mantle). Selected samples will then be subjected to seismic velocity measurements to relate textural anisotropy and degree of serpentinization to seismic field measurements. This research provides the first integrated regional data set on the effects of serpentinization of natural samples and of evolution of strain in the forearc mantle. The data will allow better interpretation of geophysical field data and the controls on subduction-zone seismicity. The MIR data coupled with detailed petrographic and textural analysis will enable more accurate analysis of field samples and interpretation of remote sensing data. Broader Impacts: This research has broad implication to large subduction zone fault studies, such as those on the San Andreas and Calvert faults. It will train both graduate and undergraduate students in the US, Japan and Canada. The work enhances the infrastructure for research and education by involving multidisciplinary research at three institutions. It also supports two female PIs, both of whom are at an EPSCoR institution (University of Hawaii). Results will be presented on the internet and on CD for informal and formal education for K-12 students, undergraduates, and the general public. The project will enhance the NSF-funded MARGINS-supported efforts in the Mariana region and ODP/IODP drilling in the Mariana forearc.