Mohr圆分析方法在川西-藏东MT剖面资料解释中的应用  

APPLICATION OF MOHR CIRCLE ANALYSIS METHOD TO INTERPRETATION OF DATA FROM MAGNETOTELLURIC SOUNDING PROFILE IN WEST SICHUAN-EAST TIBET

作　　者：孙洁[1] 晋光文[1] 白登海[1] 王立凤[1] 

机构地区：[1]中国地震局地质研究所,北京100029

出　　处：《地震地质》2003年第3期385-393,共9页Seismology and Geology

基　　金：地震科学联合基金 ( 1980 6 2 );科技部项目 ( 95110 2 )中国地震局地球物理勘探中心论著编号RECG2 0 0 2 0 1

摘　　要：用Mohr圆分析法对川西—藏东全测区 76个大地电磁测深点的资料进行了分析 ,结果表明 :测区以 2D区域构造为主要特征 ,横向各向异性不太强 ;区域构造走向大致呈近SN向 ,最大偏离不超过± 30°。文中介绍了Mohr circle analysis is a qualitative method for interpretation of magnetotelluric (MT) data. It uses various rotational invariants of impedance tensors and their composite as its basic parameters, so as to visually and clearly displays the features, such as dimensions, 2D deviation degree, anisotropy, strike orientation, and impedance of the main axis of electrical structures. The conspicuous feature of the method is that it can be used for determining the dimensions of structures. For 1D structure, the Mohr circle is degraded into a point on the abscissa. For 2D structure, the center of Mohr circle is on the abscissa, where the longer the radius of circle, the sharper the electrical anisotropy is. And for 3D structure, the center of Mohr circle deviates from the abscissa, and the farther the deviation of the center from the abscissa, the sharper the 3D feature is. The Mohr circle analysis method was used in analysis of 76 magnetotelluric sounding data from the whole sounded area in west Sichuan east Tibet. The result obtained shows that 2D regional structures are the main features of the region, and the lateral anisotropy is less intense. The strike of regional structures is approximately sub longitudinal and the maximum deviation does not exceed ±30°. The analysis result of data only from four observation sites is presented in detail here due to the limited space of the paper.

关 键 词：MT阻抗张量 Mohr圆 二维 大地电磁测深 

分 类 号：P631.24[天文地球—地质矿产勘探]