多种频率域电磁法在冷水坑矿集区的应用效果对比  

Comparison of various frequency-domain electromagnetic methods for mineral exploration in Lengshuikeng ore-concentration area

作　　者：邓居智[1,2] 郑燕青[1] 陈辉[1,2] 周彪华 吴从辉[1] 

机构地区：[1]东华理工大学地球物理与测控技术学院,南昌330013 [2]东华理工大学放射性地质与勘探技术国防重点学科实验室,南昌330013

出　　处：《地球物理学进展》2016年第6期2510-2520,共11页Progress in Geophysics

基　　金：国家自然科学基金(41164003;41404057);国家科技支撑计划(2011BAB04B03);赣鄱英才555工程项目联合资助

摘　　要：江西省冷水坑矿集区具有浅部斑岩型矿体与深部层控叠生型矿体的复杂组合.利用现代地球物理方法对矿集区地下深部结构进行了探测,对圈定地下容矿、示矿地质信息和认识地下深部成矿过程具有重要意义.本文以位于江西省贵溪市境内的冷水坑银铅锌矿田为试验研究区,开展了混场源音频大地电磁测深法(EH4)、音频大地电磁测深法(AMT)以及可控源音频大地电磁测深法(CSAMT)三种不同频率域的探测试验,研究和总结了频率域方法以及不同仪器电磁法数据采集特点和应用效果,为频率域电磁法勘探提供借鉴和参考.通过对冷水坑矿集区典型勘探线上三种电磁方法的数据处理,绘制了视电阻率和相位单点测深曲线、原始拟断面及二维反演断面图.发现单点曲线形态基本一样.由于AMT在低频段受矿区工业干扰,视电阻率曲线呈45°上升;视电阻率、相位拟断面对地下电性分层结构基本一样,总体可分为三层,且分层结构较清晰;二维反演断面能够较好反映地下高低阻异常响应,但响应效果有所差异且CSAMT法效果较好.因此在干扰严重地区,建议选用人工源发射的可控源音频大地电磁测深法(CSAMT).The Lengshuikeng ore deposit in jiangxi province owns a complex combination of a shallow porphyry ore body and deep stratiform ore body. The underground deep structure of ore concentration area can be probed by using modern geophysical methods,which has important guiding significance for understanding the causes of deep metallogenic,delineating the host rocks and ore geological information. In this paper,we chose the Lengshuikeng Ag-Pb-Zn ore field in Guixi city,Jiangxi province,as a trial site.The prospecting experiment of different combination methods were carried out by the method of mixed field source audio magnetotelluric（ EH4） sounding,audio magnetotelluric（ AMT） sounding and controlled source audio magnetotelluric（ CSAMT）. It can be used to analysis and research every method at different frequencies domain as well as acquisition characteristics and the application effect of electromagnetic methods of the different instruments, which can offer references to the frequency domain electromagnetic exploration method. By processing typical exploration line data of three kinds of frequency domain electromagnetic method in Lengshuikeng ore district,we draw apparent resistivity and phase sounding curves,original pseudo section and two-dimensional inversion section,this experimental study shows that a single point curve shape is almost the same. Since the AMT is easily interfered by the mining industry in the low frequency,the apparent resistivity curve was 45° rise;Apparent resistivity and phase pseudo section are basically the same for dividing the underground layers. Generally,stratigraphic texture can be divided into three layers,and the structure is clear. Twodimensional inversion results have good effect on distinguishing the abnormal response of high and low resistance,but it has obvious difference for subsurface characterization and the inversion result of CSAMT has better effect than others. Thus we should recommend to choose CSAMT method of artificial sources in areas of severe noise.

关 键 词：冷水坑 频率域电磁法 EH4 AMT CSAMT 二维反演 

分 类 号：P631[天文地球—地质矿产勘探]