音频大地电磁法在南岭于都-赣县矿集区银坑示范区深部矿产资源探测中的应用

The Application of Audio Magnetotelluric Method(AMT)in Nanling Yudu-Gan County Ore-Concentrated Area Yinkeng Demonstration Plot to Survey Deep Mineral Resources

本文探讨了音频大地电磁法(AMT)在南岭于都-赣县矿集区银坑示范区中深部金属矿探测中的应用效果。在该区开展AMT工作目的是了解3km以浅地层分布、岩体展布及构造特征,为深部找矿提供基础地质信息。采用AMT张量观测方案采集了5条AMT剖面的数据,经数据预处理、反演得到了电阻率随深度变化的断面图。对标本电阻率测试结果分析表明:沉积岩、变质岩及岩体存在电阻率差异,并建立了示范区的电性与地层对应关系。通过对比、分析AMT地电断面图,揭示了江背岩体、长潭岩体的空间展布及深部"无根"特征;发现了一个隐伏岩体-柳木坑岩体;推断了3km以浅变质岩系、沉积岩系地层的分布情况。研究结果表明:AMT可为"第二找矿空间"提供有益的地质信息。

In this paper,we discuss the application status of Audio magnetotelluric method （AMT）in Nanling Yudu-Gan county ore-concentrated area Yinkeng demonstration plot to survey deep mineral resources.The purpose of carrying out AMT exploration work in this area is know of the strata distribution,distribution of rock mass and structure characteristic shallower than 3 km, which provide the basic geological information for deep exploration.The data of 5 AMT profiles is measured by vector observation scheme. After the data pretreatment and inversion,we get the profile of resistivity changing with depth.Analysis of the result of the specimen resistivity test shows that resistivity difference exists between sedimentary rock, metamorphic rock and rock mass.The corresponding relation between formations and electric property is built based on the resistivity difference.Through comparison and analysis of the AMT geoelectric profiles,we obtain the space distribution feature of Jiangbei rock mass and Changtan rock mass.The lower part of then has no roots.Meanwhile,we find a concealed rock mass named Liumukeng rock mass and infer the distribution of the sedimentary strata and metamorphic strata shallower than 3 km.This study shows that AMT method can provide useful geological information for “the second prospecting space”.