摘要
为研究音频大地电磁测深法(AMT)在识别断层模型方面的可行性,结合实际电性特征,建立了不同倾角、不同倾向和不同电性的地质模型,进行了AMT的正演数值模拟;通过ZONDMT2D软件的正演计算,得出关于正演模型的视电阻率和阻抗相位拟断面图,分析了在普通和某种特定地质模型下的AMT正演响应,为之后AMT实测资料的处理和解释提供了参考。数值模拟表明:1在二维介质中,TE模式视电阻率信息对目标体反映良好,但相位资料易产生虚假异常中心;TM模型视电阻率易受静态效应影响,对横向不均匀电性体的差异具有"放大作用",其阻抗相位资料质量好,可信度高。2当断层倾角分别为30°,60°,90°时,TE、TM模式的阻抗相位拟断面图都明显优于视电阻率图。3在TM模型中,对于正断层模型,AMT正演结果会在断层顶部对应地面的投影位置附近产生一个相对"凹陷"的曲线形态;逆断层模型则会在相应位置出现相对"凸起"的曲线形态。最后,通过对西藏扎西康铅锌多金属矿整装勘查区的实测资料的分析,圈定隐伏断层在剖面上的展布,经过实际钻孔的验证,证实该正演模拟结论对于实测资料的处理和解释具有参考价值。
In order to study the effect of audio magnetotelluric method(AMT)of identifying the fault structures,we developed a forward model of the AMT responses for three kinds of geological models with different directions,inclinations and electrical properties combined with the real data.The apparent resistivity and impedance phase of the pseudo section of the forward model are computed by ZONDMT2 Dsoftware,and the AMT forward responses are analyzed in general and specific geological models,which helps to guide the processing and interpretation of AMT data.The modeling results show that for the simple 2-D model,the apparent resistivity of TE mode information has high sensitivity to the target body,but the impedance phase is easy to produce fake center.The apparent resistivity of TM mode is prone to be affected by the static effect,while the impedance phase reaction is more stable.Besides,when the dip angle of the fault models is 30,60 and 90degree respectively the impedance phase of the TM and TE modes are obviously superior to the apparent resistivity.In addition,in the normal fault,a "concave" curve is generated in the top of the fault in TM mode,while in the reverse fault,a "raised" curve is generated in the corresponding position,which can be regarded as a sign of determining the anomaly caused by the normal fault or reverse fault.The results of this study are applied to the interpretation of the data in the Zhaxikang lead-zinc ore area,Tibet.The drilling verification,proves that this model has some practical applications.
作者
梁苗
刘双
胡祥云
赵宪生
焦彦杰
Liang Miao Liu Shuang Hu Xiangyun Zhao Xiansheng Jiao Yanjie(Institute of Geophysics and Geomatics, China University of Geosciences,Wuhan 430074,China Institute of Geophysics, Chengdu University of Technology, Chengdu 610059,China Chengdu Center, China Geological Survey, Chengdu 610081, China)
出处
《地质科技情报》
CAS
CSCD
北大核心
2016年第5期231-237,共7页
Geological Science and Technology Information
基金
中国博士后科学基金(2016M590132)
中央高校基本科研业务费专项基金(CUG160609)
中国地质调查项目(12120115022701)