大地电磁各向异性二维模拟及实例分析  

The magnetotelluric anisotropic two-dimensional simulation and case analysis

作　　者：胡祥云[1] 霍光谱[1,2] 高锐[3] 王海燕[3] 黄一凡[1] 张云霞[1] 左博新[1] 蔡建超[1] 

机构地区：[1]中国地质大学地球物理与空间信息学院,武汉430074 [2]河南省地质调查院,郑州450000 [3]中国地质科学院地质研究所岩石圈研究中心,北京100037

出　　处：《地球物理学报》2013年第12期4268-4277,共10页Chinese Journal of Geophysics

基　　金：国家深部专项(SinoProbe-02-01);国家自然科学基金(批准号:41274077);湖北省自然科学基金(NO.2011CDA123)联合资助

摘　　要：经过半个多世纪的发展,国内外利用大地电磁法研究地球内部电性结构取得了令人瞩目的成就,这些研究成果多数是基于电性各向同性理论.然而地球内部普遍存在电性各向异性现象,地壳和上地幔中存在的电性各向异性是地电模型、地下结构和构造模型间一个重要的联系因素.本文首先由麦克斯韦方程出发,引入张量电导率,根据二维电性各向异性结构的特点,得到一组关于平行走向的电场分量Ex和磁场分量Hx的偏微分方程.使用有限差分法求解偏微分方程,求出Ex和Hx的近似解,并以此求得其它场分量;随后,通过对普通及特殊的二维电性各向异性结构做正演模拟,研究其对观测大地电磁场的影响,从而认识在普通及某种特定地质条件下的电磁传播特性,为其后对大地电磁实测资料的处理解释奠定理论基础;最后,以本文的研究成果为基础,将电性各向异性理论引入对实测大地电磁资料的处理解释中,通过对新疆某地的大地电磁资料做二维正演拟合解释,说明了电性各向异性现象的普遍存在,也验证了理论的正确性及算法的实用性,为今后分析解释大地电磁资料中的电性各向异性现象提供理论依据和技术指导,并开拓了对大地电磁实测资料处理的思路和方法.After more than half century development, remarkable achievements have been made on the study of earthrs interior electrical structure by using the magnetotellurie method at home and abroad. The majority of these research results are based on the electrical isotropie theory. However, the electrical anisotropy phenomenon is prevalent in the earth interior, and the presence of electrical anisotropy in the crust and upper mantle is an important link factor among geoeleetric model, underground structure and tectonic model. In this paper, the tensor conductivity has been first introduced by starting from the Maxwell equations, then getting a setof partial differential dimension electrical equations with respect anisotropic structure. to E. and H. according By using the partial to the characteristic of two- differential equations, the appropriate solution of E. and H~ has been solved, and working out other field components on the basis of E. and H.. Then, in order to recognize the characteristics of electromagnetic propagation under common and certain geological conditions, the influence on the measured magnetotelluric has been researched by the forward simulation on ordinary and special two-dimension anisotropic electrical structure, which has laid theoretical foundation for the subsequent processing and interpretation of magnetotelluric measured data. Finally, the electrical anisotropy theory is introduced in the processirlg and interpretation of magnetotelluric measured data based on the research results in the paper, and the widespread existence of electrical anisotropy phenomenon has been stated and exactness of this theory and practicability of algorithm have been verified by means of the two-dimension forward fitting interpretation on the magnetotelluric data in someplace in Xinjiang, which can provide theoretical basis and technical guidance for analyzing and explaining the electrical anisotropy phenomenon in the magnetotelluric data, and most importantly, it opens up the idea and solution in the processing of

关 键 词：大地电磁 有限差分 电性各向异性 张量电导率 

分 类 号：P631[天文地球—地质矿产勘探]