带地形的二维各向异性大地电磁测深数值模拟  

The Forward Numerical Simulation of Two-dimensional Anisotropic Magnetotelluric Sounding

作　　者：田红军[1,2] 佟铁钢[1,2] 

机构地区：[1]中南大学有色金属成矿预测教育部重点实验室,湖南长沙410083 [2]中南大学地球科学与信息物理学院,湖南长沙410083

出　　处：《工程地球物理学报》2015年第2期139-144,共6页Chinese Journal of Engineering Geophysics

基　　金：国家自然科学基金项目(编号:41227803;41374119);湖南省自然科学基金项目(编号:13JJ3011)资助

摘　　要：以往主要在水平层状地表研究大地电磁二维各向异性系数对观测值的影响。通过有限元数值模拟方法,讨论同时存在起伏地形以及各向异性对二维大地电磁测深法中TM极化模式的响应。首先给出二维各向异性介质中TM极化模式的变分问题;其次用规则矩形单元对研究区域进行剖分,用双线性函插值对变分问题进行求解;最后在地垒、地堑地形下,改变各向异性系数模拟TM极化模式中视电阻率的变化。结果表明:地垒地形对TM极化模式视电阻率曲线表现为低阻异常,地堑地形对TM极化视电阻率曲线呈现高阻异常,两种地形对观测数据的影响要远大于各向异性系数对观测值的影响。The previous research mainly studied the influence of magnetotelluric 2-D anistropic coefficient on the observation value from the perspective of horizontal layered surface.Through the finite element numerical simulation method,this paper discusses the existing of undulate topography and the TM polarization response of 2-D magnetotelluric sounding method to anisotropic coefficient.Firstly,the variation problems of TM polarization modes of two-dimensional anisotropic medium are introduced.Secondly,the studied area is divided by regular rectangular elements and the variation problems are supposed to be solved by bilinear function interpolation.Finally,the apparent resistivity of anisotropy coefficient of TM polarization mode is changed in the Horst and graben terrain.The results showed that apparent resistivity curve of TM polarization modes in horst topography appears low resistivity anomaly,and the curve in graben topography appears high resistivityanomaly.Therefore,the effects of these two kinds of topography on the observed value are much larger than that of anisotropic coefficients on the observed value.

关 键 词：大地电磁测深 TM极化模式 有限单元法 各向异性 

分 类 号：P631.3[天文地球—地质矿产勘探]