Next-generation 3D imaging of the on- and off-axis mantle and crustal magmatic systems at the Endeavour segment

Endeavour段轴上和轴外地幔和地壳岩浆系统的下一代3D成像全球洋中脊海底扩张系统占地球年度岩浆预算的约85%，主导着固体地球与水圈之间的质量和能量交换。 扩张中心下方的岩浆系统驱动着高温和低温热液活动，这些活动调节着海洋的长期化学性质，使地壳和地幔水合，支持着新的生态系统，这些生态系统的研究改变了我们对地球生命起源的看法，并沉积了宝贵的矿产资源。 全球洋中脊系统的基本单位是脊段。在一个单一的海脊段内，构造、火山和热液过程有系统的变化。 脊段随扩展速率系统地变化，具有三种基本类型：快速扩展、中间扩展和缓慢扩展。理解什么支配着扩散中心分割，就是理解地球仪环绕系统的基本单位。该项目更广泛的意义和重要性将是使用下一代地震成像方法来限制一个经过充分研究的大洋中脊段之下的岩浆系统结构。 该研究地点位于美国西海岸附近，是国际研究的重点区域，其海底观测节点是Neptune Canada的一部分，与美国海洋观测计划结盟。作为研究的一部分，该项目将支助一名初级女研究员和一名研究生。还与联合王国研究人员就创新的地震数据分析新技术开展了重要的国际合作，要了解大洋中脊的物质和能量转移，就需要绘制地幔和地壳岩浆系统及其与热液和构造过程的关系的地图。岩浆系统的位置、大小、形状和寿命取决于一些因素，如从地幔到地壳的熔体输送模式、熔体上升路径，也许最重要的是，热量去除的效率。热液流动模式又取决于热源分布和地壳渗透率。为了了解这些联系，该项目将更准确地绘制奋进号段轴上和轴外的地幔和地壳岩浆系统。主要目标是确定（i）是什么控制着地壳岩浆体的轴上和轴外特征和分布，以及（ii）热液热传递如何与地壳岩浆系统相互作用并形成地壳岩浆系统。这些目标将通过将三维各向异性旅行时间层析成像和三维全波形反演（FWI）应用于奋进号地震层析成像实验（ETOMO）的广角地震数据来实现。将生成分段尺度的压缩波速度图像，以绘制地壳岩浆体的分布图、从浅地幔通过下地壳的熔体输送模式，并推断地壳温度和熔体分数的空间变化。该研究位于奋进岭，丰富的先前结果，高质量的地震数据和地震成像方法的最新进展可以汇集在一个段，其中段中心和两端之间有强烈的对比。

Next-generation 3D imaging of the on- and off-axis mantle and crustal magmatic systems at the Endeavour segmentThe global mid-ocean ridge seafloor spreading system accounts for ~85% of Earth's annual magma budget, dominating the mass and energy exchange between the solid earth and its hydrosphere. Magmatic systems beneath spreading centers drive high- and low-temperature hydrothermal activity that modulates the long-term chemistry of the oceans, hydrates the crust and mantle, supports novel ecosystems whose study has altered our view of the origin of life on Earth, and deposits valuable mineral resources. The fundamental unit of the global mid-ocean ridge system is a ridge segment. Within a single ridge segment there are systematic variations in tectonic, volcanic and hydrothermal processes. Ridge segments vary systematically with spreading rate with three basic types: fast-, intermediate- and slow-spreading. Understanding what governs spreading-center segmentation is to understand the fundamental unit of a globe encircling system. The broader significance and importance of the project will be to use next-generation seismic imaging methods to constrain the structure of the magmatic system beneath a well-studied mid-ocean ridge segment. The study site is located off the west coast of the US and is a focus area for international research with a seafloor observing node as part of Neptune Canada, which is allied with the US Ocean Observatory Initiative. The project will support a junior female researcher and a graduate student as part of the research. There is also significant international collaboration with United Kingdom researchers on innovative new seismic data analysis techniques.Understanding mass and energy transfer at mid-ocean ridges requires mapping mantle and crustal magmatic systems and their relationship to hydrothermal and tectonic processes. The location, size, shape, and longevity of magmatic systems depend on factors such as the patterns of melt delivery from the mantle to the crust, melt ascent pathways, and perhaps most importantly, the efficiency of heat removal. Hydrothermal flow patterns are in turn determined by the distribution of heat sources and crustal permeability. To understand these linkages, the project will more accurately map mantle and crustal magmatic systems at the Endeavour segment both on- and off-axis. The primary objectives are to determine (i) what controls the characteristics and distribution of crustal magma bodies both on- and off-axis, and (ii) how hydrothermal heat transfer interacts with and shapes crustal magmatic systems. These objectives will be accomplished by applying 3D anisotropic travel time tomography and 3D full-waveform inversion (FWI) to wide-angle seismic data from a seismic tomography experiment (ETOMO) at the Endeavour. Segment-scale compressional wave velocity images will be generated to map the distribution of crustal magma bodies, the pattern of melt transport from the shallow mantle through the lower crust, and to infer spatial variations in crustal temperature and melt fraction. The study is sited at the Endeavour Ridge where a wealth of previous results, high-quality seismic data, and recent advances in seismic imaging methods can be brought together at a segment where there are strong contrasts between the segment center and ends.