Collaborative Research: CSEDI: Integrating Seismic Anisotropy, Mantle Flow, and Rock Deformation in Subduction Zone Settings

合作研究：CSEDI：在俯冲带环境中整合地震各向异性、地幔流和岩石变形

• 批准号: 2153910
• 负责人: Philip Skemer
• 金额: $ 32.15万
• 依托单位: Washington University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2153910&HistoricalAwards=false
• 关键词: Collaborative; Research; CSEDI; Integrating; Seismic; Collaborative; Research; CSEDI; Integrating; Seismic

Subduction zones are locations where one tectonic plate dives underneath another. They are an essential component of plate tectonics and the setting of the most hazardous earthquakes and volcanoes. Mantle flow above and below the subducting plate is driven by the motion of the subducting slab. The primary tool for investigating mantle flow at subduction zones is measuring the directional dependence of seismic wave speeds. Variations in wave speeds - called seismic anisotropy - arise from the alignment of minerals caused by mantle flow. However, this technique requires linking seismic observations to data on the alignment of mineral grains in deformed rocks, in the context of mantle flow. Here, the team combines state-of-the art rock-deformation experiments with models of mantle flow and models of seismic anisotropy in mantle rocks. They generate synthetic seismic waves that are compared with observations in Alaska, Cascadia, and South America. The overarching goal is to improve the understanding of mantle flow in subduction zones and better constrain plate tectonics. The project provides support for graduate and undergraduate students trained in a rich interdisciplinary environment. It also fosters outreach to K-12 students and teachers. The project outcomes will be shared with the community, notably through a multi-disciplinary conference on this topic. The project activities yield a holistic view of mantle flow, olivine texture development, and seismic anisotropy observations in subduction zones. The project is organized around three tasks. First, the researchers conduct a new set of high pressure and temperature olivine deformation experiments using the Large Volume Torsion (LVT) apparatus at Washington University in St. Louis. The aim is to determine how strain produces and subsequently modifies crystallographic preferred orientation (CPO). They use these results to produce a suite of experimentally validated parameters for use in the D-Rex texture modeling program, which simulates the formation and evolution of olivine CPO. Second, the updated D-Rex model is incorporated into new 3D models of subduction zones; these models use a nonlinear rheology and a set of alternative assumptions on the distribution of water in subduction zones. Third, the team uses the results of the numerically modeled subduction zones to simulate shear wave splitting in the mantle wedge and sub-slab mantle, using full-wavefield simulation techniques. Through these steps, the researchers define an ensemble of potential interpretations of mantle flow near subduction zones that are supported by existing and new data.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

俯冲带是一个构造板在另一个构造板上潜水的位置。 它们是板块构造的重要组成部分，也是最危险的地震和火山的设置。俯冲板上和下方的地幔流由俯冲平板的运动驱动。调查俯冲区域地幔流的主要工具是测量地震波速度的方向依赖性。波速的变化 - 称为地震各向异性 - 由地幔流引起的矿物对齐。 但是，该技术需要将地震观测与在地幔流的背景下，将地震观测与变形岩石中矿物晶粒对齐的数据联系起来。 在这里，该团队将最先进的岩石形成实验与地幔岩石中的地震各向异性模型结合在一起。它们产生的合成地震波与阿拉斯加，卡斯卡迪亚和南美的观察结果进行了比较。 总体目标是提高对俯冲区域地幔流的理解，并更好地限制板块构造。该项目为在丰富的跨学科环境中培训的研究生和本科生提供了支持。 它还促进了K-12学生和老师的宣传。该项目的结果将与社区共享，特别是通过有关该主题的多学科会议。项目活动对俯冲带中的地幔流，橄榄石纹理发展和地震各向异性观测产生了整体视野。该项目围绕三个任务进行组织。首先，研究人员使用圣路易斯华盛顿大学的大容量扭转（LVT）设备进行了新的高压和温度橄榄石变形实验。 目的是确定应变如何产生并随后修饰晶体学首选方向（CPO）。他们使用这些结果来生成一套经过实验验证的参数，以用于D-Rex纹理建模程序，该计划模拟了Olivine CPO的形成和演变。 其次，更新的D-Rex模型被整合到俯冲区的新3D模型中。这些模型使用非线性流变学和一组关于俯冲区域水分布的替代假设。第三，该团队使用数字建模的俯冲区的结果模拟了使用全波菲尔德模拟技术模拟地幔楔形和子板套中的剪切波分裂。通过这些步骤，研究人员定义了对俯冲区附近地幔流的潜在解释的集合，并得到了现有数据的支持。该奖项反映了NSF的法定任务，并被认为是通过基金会的智力优点和更广泛影响的评估标准来评估值得支持的。