基于地空频率域电磁法的深部地层极化效应探测方法

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中图分类号：P631 文献标志码：A

Abstract： The ground-air frequency-domain electromagnetic （GAFDEM） method has broad application prospects in studying deep geological structures in complex terrains. However，currentstudies and applications mainly focus on ground resistivity imaging，with limited in-depth studies on the measurement of induced polarization effects. This paper aims to systematically investigate the influence of polarization effects on GAFDEM measurement results and proposes a method for simultaneous imaging of apparent resistivity and apparent polarizability. To this end，based on Maxwell's equations and the Cole-Cole model，a forward model of electric-source ground-air frequency-domain electromagnetic response considering polarization effect is established.The influence of parameters such as resistivity and polarization rate on the airborne magnetic field is analyzed，and a method for simultaneous calculation of apparent resistivity and apparent polarizability is proposed using Sobol sensitivity analysis and particle swarm optimization. Finally， simulation experiments are conducted to verify the effectiveness of this method in identifying low-resistivity，high-polarization targets. The results show that the apparent resistivity curves for all models exhibit a characteristic dip at the low-resistivity target layer，intuitively reflecting the low-resistivity properties of the target layer. Models including polarization efects display high values at the target layer，with the anomaly amplitude increasing as polarization rate rises. The zero-polarization model shows a relatively flat apparent polarization curve. Experimental results further indicate that both ground resistivity and polarizability significantly affect the amplitude of the airborne magnetic field，with low-resistivity，high-polarization anomalies generating significant magnetic field response anomalies.

Key words： ground-air frequency-domain electromagnetic method; induced polarization effect; ColeCole model;apparent resistivity；apparent polarizability

0 引言

随着我国对矿产资源需求的不断增加，深部矿产资源勘探已成为当前国家找矿战略的重要突破口，现代常用技术方法主要包括高分辨率地震测量、重力测量、电磁法联用等，其中电磁法在矿产资源勘探中发挥了重要作用。（剩余14106字）