Finite-frequency Imaging of the Mantle Transition Zone Discontinuities

地幔过渡区不连续性的有限频率成像

• 批准号: 2017218
• 负责人: Ying Zhou
• 金额: $ 20.1万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-07-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2017218&HistoricalAwards=false
• 关键词: Finite; frequency; Imaging; Mantle; Transition

Due to increased pressure, minerals in the Earth’s subsurface undergo major phase transitions in the mantle transition zone at depths of about 410 km and 660 km. Processes in the Earth's mantle transition zone provide important constraints on the mass exchange between the shallower upper mantle and the deeper lower mantle. Those are dynamic processes that are responsible for plate tectonics, earthquakes and volcanoes. This research takes advantage of a new seismic imaging theory and data collected by seismic stations around the world to map the structure of the mantle transition zone. This research aims to advance understanding of mantle dynamics with focuses on major subduction zones (where massive oceanic plates subduct into the deep mantle) as well as volcanic hotspots in global oceanic regions. High-resolution images of the mantle transition zone will be made available to the broader Geosciences community for future multidisciplinary studies. Hands-on course projects and labs based on this research will be developed and implemented in undergraduate teaching, and a graduate student will be supported and trained. Slab pull is generally considered as the dominant force that drives the global movement of tectonic plates. This convection mode is well constrained in the upper mantle but the convection pattern in the mid mantle is more speculative. This research will build a global dataset of finite-frequency travel time measurements of SS precursors to image the global structure of the 410-km and 660-km discontinuities based on Born sensitivities calculated in the framework of traveling-wave mode coupling. Finite-frequency receiver function measurements at GSN and USArray stations will be used as complementary datasets to improve regional resolution beneath continents. The new high-resolution MTZ discontinuity models will be analyzed together with published seismic wave speed and anisotropy models to advance fundamental understanding of Earth processes in the mantle transition zone, with focus on the structure and dynamics of stagnant slabs in subduction zones as well as thermal and compositional variations beneath oceanic hotspots.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.

由于压力增加，地球地下的矿物在深度约410公里和660公里的地幔过渡带中经历主要的相变。 地幔过渡带的过程对浅部上地幔和深部下地幔之间的物质交换提供了重要的制约。这些都是造成板块构造、地震和火山的动态过程。 这项研究利用一种新的地震成像理论和世界各地地震台站收集的数据来绘制地幔过渡带的结构。 这项研究旨在促进对地幔动力学的理解，重点是主要的俯冲带（巨大的海洋板块俯冲到地幔深处）以及全球海洋地区的火山热点。 地幔过渡带的高分辨率图像将提供给更广泛的地球科学界，供今后进行多学科研究。 基于本研究的实践课程项目和实验室将在本科教学中开发和实施，研究生将得到支持和培训。板片拉力一般被认为是驱动全球构造板块运动的主导力量。 这种对流模式在上地幔中受到很好的约束，但在中地幔中的对流模式更具投机性。 这项研究将建立一个全球数据集的有限频率旅行时间测量的SS前兆图像的全球结构的410公里和660公里的不连续性的基础上计算的Born灵敏度的框架内的行波模式耦合。GSN和USAray台站的双频接收器功能测量结果将用作补充数据集，以提高大陆之下的区域分辨率。新的高分辨率MTZ不连续模型将与已发表的地震波速度和各向异性模型一起进行分析，以促进对地幔过渡带地球过程的基本理解，重点研究俯冲带停滞板块的结构和动力学，以及海洋热点下的热力和成分变化。该奖项反映了NSF的法定使命，并被认为值得通过评估予以支持使用基金会的知识价值和更广泛的影响审查标准。

项目成果

Stagnant slabs and their return flows from finite-frequency tomography of the 410-km and 660-km discontinuities

410 公里和 660 公里间断面的有限频率层析成像显示的停滞板片及其回流

• DOI: 10.1029/2020jb02109
• 发表时间: 2021
• 期刊: Journal of geophysical research
• 作者: Guo, Z;Zhou, Y.
• 通讯作者: Zhou, Y.

Age‐Independent Oceanic Plate Thickness and Asthenosphere Melting From SS Precursor Imaging

• DOI: 10.1029/2022jb024805
• 发表时间: 2023-02
• 期刊: Journal of Geophysical Research: Solid Earth
• 作者: Shuyang Sun;Ying Zhou

Transient variation in seismic wave speed points to fast fluid movement in the Earth's outer core

地震波速度的瞬态变化表明地球外核中的流体快速运动

• DOI: 10.1038/s43247-022-00432-7
• 发表时间: 2022
• 期刊: Communications Earth & Environment
• 影响因子: 7.9
• 作者: Zhou, Ying