二维大地电磁主轴各向异性理论模型反演  

Two-dimensional magnetotelluric inversion for principal axis anisotropy theoretical models

作　　者：张双全 李桐林[1] ZHANG Shuang-quan;LI Tong-lin(College of Geo-exploration Science and Technology,Jilin University,Changchun 130026,China)

机构地区：[1]吉林大学地球探测科学与技术学院,长春130026

出　　处：《世界地质》2021年第3期697-702,共6页World Geology

基　　金：国家重点研发计划(2017YFC0601606);中国博士后科学基金特别资助(站前)项目(2020TQ0114)资助

摘　　要：系统阐述了广泛认可的二维有限差分正演算法理论,再考虑一种特殊情况,将任意各向异性情况的电导率简化为只有对角线的主轴电导率,得到电场E x与磁场H x解耦的方程组,并利用TE模式只与σxx有关、TM模式只与σyy和σzz有关的特点,使用最小二乘法将TM模式单独反演计算。在y轴方向上,反演结果较为准确地还原了各向异性异常体的存在,包括位置和y轴方向上的电阻率信息,但在z轴方向上没有取得明显的效果,验证了前人关于z轴方向上的电阻率由于σzz不敏感,无法成功恢复的研究结论。The widely accepted algorithm for the 2D finite-difference modeling of magnetotelluric fields is systematically analyzed in this paper.Considering one specified condition,the authors assume a principal axis anisotropy theoretical model to acquire the decupled system of partial differential equations for the components of the electromagnetic field,E x and H x.With the features that the values of E x in E-mode only have relationships withσxx,and the values of H x in H-mode only have relationships withσyy andσzz,the authors make an inversion of H-mode of principal axis anisotropy using the least-squares method.The results show the good effects including the resistivity recovery and the delineation of abnormal body position in y directions but unobvious effects in z directions,which verifies the former conclusion that the resistivity in z directions can t be recovered due to the insensitiveσzz.

关 键 词：大地电磁 有限差分 电性各向异性 二维反演 

分 类 号：P631.3[天文地球—地质矿产勘探]