Mapping P-wave Azimuthal Anisotropy near the Core-Mantle Boundary using Novel Observations of Core-Diffracted waves PcSdiff

使用核心衍射波 PcSdiff 的新观测来绘制核心-地幔边界附近的 P 波方位各向异性

基本信息

批准号：
NE/T001372/1
负责人：
Teh-Ru Alex Song
金额：
$ 50.74万
依托单位：
University College London
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2019
资助国家：
英国
起止时间：
2019 至无数据
项目状态：
未结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FT001372%2F1
关键词：
Mapping wave Azimuthal Anisotropy near

项目摘要

While the Earth's surface marks the boundary between the atmosphere and the solid earth, the core-mantle boundary (CMB) separates the solid mantle from the liquid core, modulating the loss of heat and driving the earth's dynamo and magnetic field.Constraining seismic anisotropy in the CMB region is challenging. Previous results on S wave anisotropy are subjected to some limitation in geographical sampling, azimuthal coverage or/and proper correction of upper mantle seismic anisotropy, which is not trivial. None of previous studies, neither in isolation or in combination, regional or global scale, has yielded any estimate of P-wave azimuthal anisotropy in the D'' layer. We do NOT know P wave anisotropy property of ultra-low velocity zones (ULVZs), large low-velocity provinces (LLVPs) or slab graveyards.We will use novel observations of core-diffracted PcSdiff wave in the radial P wave receiver function stacks to constrain P wave azimuthal anisotropy in the core-mantle boundary, with a particular focus on the regions of possible slab graveyard, ULVZs and the base of LLVPs. These renewed descriptions of P wave anisotropy models will be used to explore outstanding questions including the rheology or the deformation mechanism, the mantle flow patterns near the core-mantle boundary and the nature of LLVPs and ULVZs.A series of outstanding questions can be much better addressed with our new seismic observations:What's the rheology and deformation mechanism operating in the D'' layer? How did the slab graveyard, LLVPs and ULVZs deform and their anisotropy properties? Are LLVPs and ULVZs compositional distinctly from the rest of the D'' layer?Is the deformation accommodated by bridgmanite, post-perovskite or secondary minerals such as ferropericlase and calcium-perovskite? Is the dislocation creep, responsible for upper mantle seismic anisotropy, operating in the D'' layer?These unprecedentedly rich observations will provide renewed constraints on fundamental processes relevant to the Earth's interior and evolution.

尽管地球的表面标志着大气与固体地球之间的边界，但核心掩体边界（CMB）将固体地幔与液态芯分开，调节热量的损失并驱动地球的发电机和磁场。约束CMB区域中的地震各向异性。 S波各向异性的先前结果在地理采样，方位角覆盖范围或/和适当校正上地幔地震向上的校正方面受到一定限制，这并非微不足道。先前的研究均未孤立或组合，区域或全球尺度，均未产生d'层中P波方位各向异性的任何估计。我们不知道超低速度区（ULVZ），大型低速省（LLVP）或板墓墓地的P波各向异性特性。我们将使用核心 - 脱落的PCSDIFF波的新颖观察到径向P波接收器在prove pove pove pove pove pove pove pove pow a pove a pow a powsion a zim cornies cornies corece corece corecion的核心群中的核心群体的核心群，该核心均具有核心的核心。墓地，Ulvzs和LLVPS的基础。 P Wave各向异性模型的这些更新的描述将用于探索包括流变学或变形机制，核心 - 核心边界附近的地幔流动模式以及LLVPS和ULVZ的性质，一系列出色的问题可以更好地解决我们的新的地震观察：Rheology和Deformative机制的操作'''''''''''''''''''''''''''，平板墓地，LLVP和ULVZ如何变形及其各向异性特性？ LLVP和ULVZ的组成是否明显与d'层的其余部分？在d'层中运行的上地幔地震各向异性的蠕变是否是蠕变？这些空前的丰富观察结果将对与地球内部和进化相关的基本过程产生重新限制。