Comprehensive Study With CSAMT And IP Methods On Searching Lead-zinc Deposit

IP(induced polarization) is a commonly used method of electrical prospecting, but for some structural and lithological area, the noise of measurement is serious and the electromagnetic signal is weak, single electrical prospecting method in search for deep target always can’t meet our requirements on anti-interference ability and reliability of interpretation, and it has seriously affected the detection of the deep mineral resources, the CSAMT method is just to make up for the lack of single use of IP method. Therefore this article studies on looking for lead zinc mine with the method of CSAMT and IP.Firstly the development status of CSAMT and IP method is introduced in this paper. The causes of abnormal data, and the correction method of source effects, static effect and proximity effect in CSAMT measurement are analyzed in this paper too. At the same time, the Bostick method and nonlinear conjugate gradient method for solving inverse problem are introduced. Different theoretical models are established for comparative analysis of the imaging of the TE, TM model, we establish the TM model as the inversion model to verify the reliability of the software on the interpretation and inference. Then the finite element method is used to establish the induced polarization theory forward model, the forward calculation results are inversed by the damping least square method. The anomaly characteristics and trend of the inversion results are analysed, the imaging rule of resistivity and polarizability are summarized to provide the basis for the inversion of measured data.Finally, taking lead-zinc mining area as an example in Guizhou Province, combining with the geological data and rock(ore) property, fracture orientation and alteration zone in three inversion profiles of CSAMT method are determined. According to the IP survey results, a pseudo section is chosen to carry out the IP sounding. Then anomaly characteristics and the trend of low resistivity and high polarization body are deined to infer lead zinc ore belt or possible metallogenic prospect area.Through the application of CSAMT and induced polarization method in complex structure and lithology area, conclusions are gained as follows:1, Data distortion in CSAMT method is mainly caused by the static effect, which can be corrected by the curve shifting and spatial filtering.2, CSAMT imaging results can well display the alteration zone, different conductivity anomaly and fault, to provide the basis for the analysis of ore controlling factors and metallogenic mechanism.3, Polarization rate in inversion results of induced polarization method provides plenty of information for the rock(ore) anomaly characteristics, the contrasting of resistivity and apparent resistivity section of the CSAMT provides inference basis on anomaly interpretation.4, Comprehensive detection of CSAMT and induced polarization method improves the credibility of the interpretation of detection results. And it demonstrates the effectiveness and feasibility of the comprehensive model in deep exploration of lead zinc mine in the complex structure and lithology area.