Collaborative Research: SERPENT: Serpentinite, Extension and Regional Porosity Experiment across the Nicaraguan Trench

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。地球的薄岩壳，即岩石圈，被分解成由不断运动的薄板组成的马赛克。沿着板块之间的一些边界，一个板块滑到另一个板块的下面，并在一个被称为俯冲的过程中被消耗掉。大地震和猛烈的火山爆发大多发生在俯冲带。这两个过程都受到随着板块下沉进入内部的水量的显著影响，但由于进入俯冲系统的水量仍然很少受到限制，因此对这些过程的了解仍然很少。水的主要载体是蛇纹石矿物，其中一个主要的不确定因素是由蛇纹石化的上地幔带入俯冲系统的水量。电磁地球物理方法对地球深处的水的存在和浓度很敏感。该项目包括沿尼加拉瓜附近300公里剖面进行的大规模电磁实验，该剖面显示地壳中存在与断层有关的大量流体循环，可能在上地幔中也存在，并且在邻近的陆上火山中存在高Ba/La比率和水含量，表明有强烈的板块流体输入到弧融过程中。本次调查将结合可控源电磁学（CSEM）与宽带和长周期大地电磁学（MT），提供从海底到上地幔的电导率结构的全面图像，代表了中美洲俯冲带这部分的整个输入。除了提高我们对产生地震和火山爆发过程的理解的社会意义外，该项目还将促进国际科学合作并支持两名博士生。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The thin, rocky shell of the Earth, the lithosphere, is broken into a mosaic of thin plates that are inconstant motion. Along some boundaries between plates, one slides beneath the other and is consumed in a process known as subduction. Most of great earthquakes and violent volcanic eruptions occur at subduction zones. Both of these processes are significantly affected by the amount of water that is carried into the interior with the downgoing plate, but these processes remain poorly understood because the amount of water entering the subduction system remains poorly constrained. A major carrier of water is the mineral serpentine, and one of the major uncertainties is the volume of water that is being carried into the subduction system by serpentinized upper mantle. Electromagnetic geophysical methods are sensitive to the presence and concentration of water at depth in the Earth. This project consists of a large-scale electromagnetic experiment along a 300 km profile off Nicaragua in a region that shows evidence for substantial fault related fluid circulation in the crust and possibly in the upper mantle, and high Ba/La ratios and water contents in adjacent onshore volcanics suggesting a strong slab fluid input into the arc-melting. This survey will combine controlled-source electromagnetics (CSEM) with broadband and long period magnetotellurics (MT) to provide a comprehensive picture of the conductivity structure from the seafloor to the upper mantle, representing the entire input into this part of the Central American subduction zone. In addition to the societal relevance of improving our understanding of processes that produce earthquakes and volcanic eruptions, this project will promote international scientific cooperation and support two Ph.D. students.