Mapping Small-Scale Structure Above the Core-Mantle Boundary

WyessionEAR-0207751这个项目的目的是通过研究与地幔底部D“相互作用的剪切波的小尺度区域变化，促进我们对核-地幔边界地区地球物理的理解。具体地说，调查人员将寻找CMB地幔热柱、化学边界层和俯冲板块基础的直接证据，因为不断增长的宽带阵列数据数据库提供了更高的分辨率。CMB在岩石圈以下的地球上表现出无与伦比的复杂性和多变性。作为岩石地幔和液态外核之间的主要化学和热边界层，CMB可能在地幔内部和地核之间的物质循环和热量传递中发挥着重要作用。研究人员将具体解决以下问题：1)地幔热柱是否在D“形成？2)D”内是否存在横向离散的化学边界层？3)板块是否到达CMB？D“结构的一维模型将使用反射率合成器生成，但最终的模型也将使用全3D合成器进行测试，该方法使用Komatitsch和Tromp(2001)的光谱元素方法，该方法已安装在华盛顿大学的SGI并行处理机上。

WysessionEAR-0207751 The aim of this project is to advance our understanding of the geophysics of the Core-mantle boundary (CMB) region through examination of small-scale regional variations in shear waves that interact with D", the base of the mantle. Specifically, the investigators will look for direct evidence of the foundations of mantle plumes, chemical boundary layers, and subducted slabs at the CMB with the increased resolution provided by the growing database of broadband array data. The CMB displays complexity and variability unequalled within the sub-lithospheric earth. As a major chemical and thermal boundary layer between the rocky mantle and liquid outer core, the CMB likely plays significant roles in the circulation of mass, as well as the transfer of heat both within and between the mantle and core. The investigators will specifically address the following questions: 1) Do mantle plumes form in D"? 2) Are there laterally discrete chemical boundary layers within D"? 3) Do slabs reach the CMB? One-dimensional models of D" structure will be generated using reflectivity synthetics, but final models will also be tested with fully 3D synthetics using the spectral-element method of Komatitsch and Tromp (2001), which has been installed on Washington University's SGI parallel processing machine.