CAREER: Geodynamics of subducting slabs in the Earth's deep mantle from seismic anisotropy

职业：地震各向异性研究地幔深部俯冲板片的地球动力学

• 批准号: 1150722
• 负责人: Maureen Long
• 金额: $ 53.99万
• 依托单位: Yale University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-04-01 至 2017-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1150722&HistoricalAwards=false
• 关键词: CAREER; Geodynamics; subducting; slabs; Earth

Subduction zones are among the most important tectonic features on the Earth's surface and represent prime sites for earthquakes, volcanoes, and tsunami hazards. Subduction is also vitally important for understanding the Earth's interior; Earth's long-term evolution is driven by the dynamics of the mantle, and the recycling of oceanic plates back into the mantle through subduction is a major driver for mantle processes. Understanding how slabs sink from the surface to the base of the mantle - and how they interact with the mantle around them - is crucial for understanding the mantle as a dynamic system. The scientific challenge that this CAREER project aims to address is to understand how subducting slabs deform the mantle around them as they descend through the deep mantle using measurements of seismic waves.Observations and modeling of seismic anisotropy will be used to probe subduction dynamics in three regions: the deep upper mantle, the transition zone, and the lowermost mantle. I will examine the pattern of anisotropy and flow in the deep upper mantle beneath subducting slabs, using detailed shear wave splitting data sets to test hypotheses for controls on sub-slab mantle flow. I will explore how subducting slabs deform the transition zone and uppermost lower mantle and whether the style of deformation is related to the dynamic behavior of "stagnant" vs. "non-stagnant" slabs. Finally, I will interrogate the geometry of anisotropy at the base of the mantle in the D" layer, with the goal of understanding how slab remnants impinging on the core-mantle boundary (CMB) drive flow, and how flow patterns are related to other structures above the CMB such as low shear velocity provinces. The research component of this project will be complemented by an education and outreach effort which will focus on providing high school teachers with research experience on broadband field seismology deployments through a pilot program to be called FEST (Field Experiences for Science Teachers). A prime strategy for translating research into the structure and dynamics of the deep Earth to the general public is to involve teachers in deep Earth research, and field-based projects will offer a highly immersive and meaningful research experience.

俯冲带是地球表面最重要的构造特征之一，是地震、火山和海啸灾害的主要场所。俯冲对于了解地球内部也至关重要。地球的长期演化是由地幔动力学驱动的，而海洋板块通过俯冲作用返回地幔是地幔过程的主要驱动力。了解板块如何从地表下沉到地幔底部，以及它们如何与周围的地幔相互作用，对于理解地幔作为一个动态系统至关重要。该职业项目旨在解决的科学挑战是利用地震波测量来了解俯冲板片在穿过深部地幔下降时如何使周围的地幔变形。地震各向异性的观测和建模将用于探测三个区域的俯冲动力学：上地幔深处、过渡带和最下地幔。我将研究俯冲板块下方深层上地幔的各向异性和流动模式，使用详细的剪切波分裂数据集来检验控制板块下地幔流动的假设。我将探讨俯冲板块如何使过渡带和最上层的下地幔变形，以及变形的方式是否与“停滞”板块与“非停滞”板块的动态行为有关。最后，我将探讨 D" 层地幔底部各向异性的几何形状，目的是了解撞击核幔边界 (CMB) 的板片残余物如何驱动流动，以及流动模式如何与其他流动模式相关。该项目的研究部分将得到教育和推广工作的补充，重点是通过即将实施的试点计划为高中教师提供宽带现场地震学部署的研究经验。将研究成果转化为地球深部结构和动力学的一项主要策略是让教师参与地球深部研究，而基于实地的项目将提供高度身临其境且有意义的体验。研究经验。