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再循环回地幔是地幔过程的主要驱动力。了解板块如何从地幔表面下沉到底部-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。CAREER项目旨在解决的科学挑战是通过测量地震波来了解俯冲板块在通过深部地幔下降时如何使其周围的地幔变形。将使用地震各向异性的观测和建模来探测三个区域的俯冲动力学：深部上地幔，过渡带和最低地幔。我将研究模式的各向异性和流动在俯冲板下的深部上地幔，使用详细的剪切波分裂数据集来测试假设的控制板下地幔流。我将探讨俯冲板块如何变形的过渡带和最上部的下地幔和变形的风格是否与“停滞”与“非停滞”板块的动态行为。最后，我将询问在D”层的地幔底部的各向异性的几何形状，目的是了解板片残留物如何撞击核幔边界（CMB）驱动流动，以及流动模式如何与CMB上方的其他结构（如低剪切速度区）相关。该项目的研究部分将通过教育和推广工作来补充，重点是通过一个名为FEST（科学教师现场经验）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。将研究转化为地球深部的结构和动力学的一个主要战略是让教师参与地球深部的研究，实地项目将提供一个高度身临其境和有意义的研究经验。