地壳分层各向异性的接收函数研究

发布时间：2018-04-26 16:41

本文选题：地壳各向异性 + 接收函数　；参考：《中国地震局地质研究所》2016年博士论文

【摘要】：大陆动力学是当今固体地球科学各领域研究的主导方向。尽管大陆动力学研究所涉及的问题十分广泛,但其核心问题是研究大陆的变形及其动力学机理。地球介质的各向异性与其矿物组成、温压条件、应力状态以及变形历史密切相关,因此,地球介质的各向异性参数已成为推测地下不同层位介质变形的重要依据。早期的研究认为,地球内部的各向异性主要源自地幔物质在高温高压环境下塑性流动形成的橄榄石晶格优势排列,且主要表现在上地幔或者上地幔的顶部,而地壳的各向异性可以忽略。但是,近年来远震P波接收函数研究的结果业已表明,不但地壳各向异性的影响不可忽略,而且地壳不同层位的各向异性及其形成机理并不相同。因此,关于地壳各向异性的研究不但对测定岩石圈地幔的各向异性是重要的,而且对于了解地壳不同层位的变形方式具有重要意义。远震体波接收函数现已成为研究地壳各向异性的重要方法。但是,鉴于地壳介质的复杂性,如何从远震体波接收函数中提取不同深度的各向异性参数仍是一个有待不断深入研究的课题。利用远震体波接收函数研究地壳各向异性主要面临两方面的困难:1)地壳介质及其横向非均匀结构引起的散射波场常常给提取各向异性参数带来难以容忍的干扰;2)利用远震体波接收函数研究地壳各向异性有赖于完整方位的接收函数波场,但是,由于台站和地震事件分布的限制,接收函数的方位缺失常常给各向异性参数的测定带来困难。本文的主要工作包括:1)在已有研究的基础上,利用广义反射透射系数矩阵方法计算的合成地震图,进一步研究了分层地壳各向异性介质接收函数随反方位角(back azimuth)变化及不同层位各向异性参数对接收函数波场的影响;2)将曲波变换理论引入远震接收函数研究,并将压缩感知理论与曲波变换去噪相结合,实现了在重建缺失数据波场的同时,对接收函数中横向散射的压制;3)通过引入粒子群优化理论,发展了分层各向异性接收函数全局反演算法;4)将本文发展的方法实际应用于我国川西台阵数据的解释。本文的工作得到以下研究结果:1)双层各向异性参数相同时,它们与单层的各向异性特征基本相同,不但各层的各向异性参数,而且各向异性参数的层间差异对接收函数各向异性特征有较大影响;2)接收函数各向异性特征对介质各向异性对称轴的方位角比对其倾角更为敏感;3)接收函数的切向分量较其径向分量对各向异性参数的改变更为敏感;4)与各向同性薄层不同,各向异性薄层可以导致其转换震相的离散;5)壳内层间各向异性薄层对接收函数波场的影响十分有限,但沉积盖层的混响会干扰地壳各向异性参数的估计;6)数值及观测数据的验证结果表明,本文的曲波接收函数去噪技术可以有效地压制地壳介质横向非均匀引起的散射噪声,缺失方位的接收函数可以正确重建,本文的方法既可用于单台-多事件的数据集,也可用于单个事件-阵列观测的数据去噪,但单台-多事件数据集的结果优于阵列观测的情况;7)数值及观测数据的验证结果表明,在各向同性速度模型确定的前提下,本文发展的接收函数粒子群反演方法能够可靠地提取地壳分层各向异性参数,接收函数反演有利于分层各向异性的解析;8)反演中曲波去噪技术的引入,对正确地解析不同层位的各向异性参数具有重要价值;9)川西台阵接收函数的研究结果表明,青藏高原东部地壳各向异性具有分层性,不同层位各向异性的差异支持地壳不同层位变形方式不同。总之,本文的工作结果为接收函数的各向异性解释提供了新的理论依据。但是,鉴于青藏高原东部地壳结构的复杂性,其分层各向异性的研究仍有待于进一步深入。
[Abstract]:Continental dynamics is the leading direction of the research in various fields of solid earth science. Although the problems involved in the study of continental dynamics are very extensive, the core problem is to study the deformation and dynamics of the continent. The anisotropy of the earth's medium is closely related to its mineral composition, temperature bar, stress state and the history of deformation. Therefore, the anisotropic parameters of the earth's media have become an important basis for speculating on the deformation of the different layers of the earth's underground. The early studies suggest that the anisotropy of the earth's interior is mainly derived from the permutation of the olivine lattice formed by the plastic flow of the mantle material under high temperature and high pressure, and mainly in the upper mantle or the top of the upper mantle. The anisotropy of the crust can be ignored. However, in recent years, the results of the study on the P wave receiving function of the far earthquake have shown that the anisotropy of the crust can not be ignored, and the anisotropy and the formation mechanism of the different layers of the crust are different. Therefore, the study of the anisotropy of the crust not only is the analysis of the anisotropy of the lithosphere mantle. The heterosexual is of great importance and is of great significance for understanding the deformation modes of different layers of the earth's crust. The receiver function of the distant seismic body wave has now become an important method to study the anisotropy of the earth's crust. However, it is still a matter of question how to extract the anisotropic parameters of the different depth from the receiver function of the crustal body. The study of the crustal anisotropy is mainly faced with two difficulties: 1) the scattered wave fields caused by the crustal medium and its lateral inhomogeneous structure often bring intolerant interference to the extraction of anisotropic parameters; 2) the study of the anisotropy of the crust by the receiver function of the distant seismic body wave depends on the anisotropy of the crust. The full azimuth of the receiving function wave field, however, due to the limitation of the distribution of stations and seismic events, the loss of azimuth of the receiving function often brings difficulties for the determination of the anisotropic parameters. The main work of this paper includes: 1) based on the existing research, the synthetic seismogram calculated by the generalized reflection transmission coefficient matrix method is further studied. The influence of the change of the receiving function of the layered crust anisotropic medium with the anti azimuth angle (back azimuth) and the anisotropic parameters of the different layers on the wave field of the receiving function is investigated. 2) the Qu Bo transform theory is introduced into the study of the remote seismic reception function, and the compression perception theory is combined with the Qu Bo transform denoising to realize the same reconstruction of the missing data wave field. The suppression of transverse scattering in the receiving function; 3) by introducing the particle swarm optimization theory, the global inversion algorithm of the layered anisotropic receiving function is developed; 4) the method developed in this paper is applied to the interpretation of the data of Western Sichuan array in our country. The results of this paper are as follows: 1) when the double anisotropic parameters are the same, they are the same. The anisotropy of single layer is basically the same, not only the anisotropic parameters of each layer, but also the difference between the layers of the anisotropic parameters has great influence on the anisotropy of the receiving function; 2) the anisotropy of the receiving function is more sensitive to the azimuth angle of the anisotropic symmetric axis of the medium than the inclination angle; and 3) the tangential component of the receiving function is more than that of the one. The radial component is more sensitive to the change of anisotropic parameters; 4) unlike the isotropic thin layer, the anisotropic thin layer can lead to the discrete phase of the converted seismic phase; (5) the influence of the anisotropic thin layer on the wave field of the receiver is very limited, but the reverberation of the sedimentary cover will interfere with the estimation of the anisotropic parameters of the crust; 6) numerical and observation The results of data verification show that the Qu Bo receiver function denoising technique can effectively suppress the scattering noise caused by the lateral heterogeneity of the crustal medium, and the receiving function of the missing azimuth can be correctly reconstructed. This method can be used not only in single platform multi event data sets, but also in single event array observation data de-noising, but single event array observation. The results of the platform multi event data set are better than the array observation. 7) the results of numerical and observational data show that, under the premise of the isotropic velocity model, the proposed method of receiving function particle swarm optimization can reliably extract the stratified anisotropic parameter of the crust, and the inversion of the receiver function is beneficial to the stratified anisotropy. Analysis; 8) the introduction of Qu Bo denoising technology in the inversion is of great value to correctly analyze the anisotropic parameters of different layers. (9) the research results of the reception function of the Western Sichuan array show that the crust anisotropy in the east of the Qinghai Tibet Plateau is stratified, and the difference between the anisotropy of different layers supports the different deformation modes of the different layers of the crust. In a word, The results of this paper provide a new theoretical basis for the interpretation of the anisotropy of the receiving function. However, in view of the complexity of the crust structure in the east of the Qinghai Tibet Plateau, the study of the stratified anisotropy remains to be further studied.

【学位授予单位】：中国地震局地质研究所
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P541;P315.2

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