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》(Public Law 111-5)资助的。岩石圈是地球上薄薄的岩石外壳，被分解成不断运动的薄板的马赛克。沿着板块之间的一些边界，一个板块在另一个板块之下滑动，并在一个被称为俯冲的过程中被消耗。大多数大地震和猛烈的火山喷发都发生在俯冲带。这两个过程都受到下沉板块进入内部的水量的显著影响，但这些过程仍然知之甚少，因为进入俯冲系统的水量仍然很少受到限制。水的主要载体是矿物蛇纹石，其中一个主要的不确定因素是蛇纹岩上地幔带进俯冲系统的水量。电磁地球物理方法对地球深处水的存在和浓度很敏感。该项目包括沿尼加拉瓜附近300公里剖面的大型电磁实验，该区域显示地壳和可能的上地幔中有大量与断层有关的流体循环，以及邻近陆上火山岩中的高BA/La比值和水含量，表明强烈的板条流体输入到熔弧中。这项调查将结合可控源电磁学(CSEM)和宽带长周期大地电磁(MT)，提供从海底到上地幔的导电性结构的全面图景，代表中美洲俯冲带这一部分的全部输入。除了提高我们对地震和火山喷发过程的理解的社会相关性外，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.