地球物理学进展 ›› 2019, Vol. 34 ›› Issue (4): 1391-1397.doi: 10.6038/pg2019CC0247

• 应用地球物理学Ⅰ(油气及金属矿产地球物理勘探) • 上一篇    下一篇

音频大地电磁测深(AMT)约束下的重力三维反演应用研究——以越城岭岩体北缘隐伏岩体为例

陈长敬1,2,刘圣博1,2,*(),黄理善3   

  1. 1. 中国地质调查局武汉地质调查中心,武汉 430205
    2. 中国地质调查局花岗岩成岩成矿地质研究中心,武汉 430205
    3. 中国有色桂林矿产地质研究院,广西桂林 541000
  • 收稿日期:2018-09-22 修回日期:2019-05-19 出版日期:2019-08-20 发布日期:2019-08-30
  • 通讯作者: 刘圣博 E-mail:sambolxyy@163.com
  • 作者简介:陈长敬,男,1982年生, 硕士,工程师,主要从事电磁法勘查及反演计算研究工作.(E-mail: 601761571@qq.com)
  • 基金资助:
    中国地质调查局区域地质调查项目(DD20160035-03)

3D inversion of gravity under audio frequency magnetotelluric method (AMT) constraint: a case study of the concealed rock mass in the northern margin of Yuechengling rock mass

CHEN Chang-jing1,2,LIU Sheng-bo1,2,*(),HUANG Li-shan3   

  1. 1. Wuhan Center of China Geological Survey, Wuhan 430205, China
    2. Research Center for Petrogenesis and Mineralization of Granitoid Rocks,China Geological Survey,Wuhan 430205, China
    3. China Nonferrous Metals(GuiLin) Geology And Mining Company Limited, Guangxi Guilin 541000, China
  • Received:2018-09-22 Revised:2019-05-19 Online:2019-08-20 Published:2019-08-30
  • Contact: Sheng-bo LIU E-mail:sambolxyy@163.com

摘要:

越城岭岩体是中南地区重要的钨锡锑等多金属矿集区,近年来大量地质地球物理勘查等工作表明,岩体北缘大牛头寨矿集区存在着隐伏的中酸性岩体.中南片区中酸性岩较围岩属于低密度和高电阻率岩石,具备了重力勘探和音频大地电磁测深(AMT)识别隐伏岩体的前提.AMT反演在垂向上分辨率较高,能高精度识别隐伏岩体的边缘.根据地表岩石物性的统计结果,将AMT反演解释的成果转换为重力约束反演的密度边值条件,进行重力三维约束反演.并对比了重力三维无约束反演的结果,表明AMT约束下的重力三维反演能够提高识别隐伏岩体的精度,并且其精度在横向空间上有一定程度的延展.反演结果表明,隐伏岩体顶界面平均埋深为800~1000 m,最浅处为大竹山约200 m;反演的岩层密度与岩石物性相对变化较一致;隐伏岩体存在多个舌状岩柱侵入地表,为地表成矿提供了物质来源.根据岩体与成矿的关系,该研究成果为大牛头寨矿集区深部找矿指明了方向,为该区域地质矿产进一步工作提供了重要信息.

关键词: 大牛头寨, 越城岭岩体, 音频大地电磁, 重力三维反演, 隐伏岩体

Abstract:

The acidic-intermediate rock (Yuechengling rock mass) is an important tungsten tin antimony and other polymetallic ore field in the south-central areas. In recent years, according to research on a large number of geological and geophysical prospecting, there is a concealed acidic-intermediate rock in the Daniutouzhai ore field of the northern margin of the rock mass. The acidic-intermediate rock in the south-central areas is of low density and high resistivity in contrast to the hosting rock, it has the precondition of gravity exploration and Audio frequency Magnetotelluric method (AMT) to identify concealed rock mass. AMT inversion has high resolution in vertical and can identify the edge of concealed rock mass with high accuracy. According to the statistical results of the petrophysics of the outcropping rock, the AMT inversion interpretation is converted into the density boundary conditions of the gravity constraint inversion, and the three-dimensional inversion of gravity under constraints was carried out. The results of the three dimensional inversion of gravity show that the three-dimensional inversion of gravity under the AMT constraint can improve the accuracy of identifying the concealed rock mass, there is a degree of extension in the horizontal space. The inversion results show that the average depth of the top interface of the concealed rock mass is 800~1000 m, and the shallower is about 200 m in Dazhu mountain; the inversion of the rock density is in accordance with the rock petrophysics, and the concealed rock mass has several shape of tongue rock pillar extending to the surface, It provides material source for surface mineralization. According to the relationship between rock mass and mineralization, the research results indicate the direction of the deep ore prospecting in the Daniutouzhai area, and provide important information for further work of the geological and mineral resources in this region.

Key words: Daniutouzhai area, Yuechengling rock mass, Audio frequency magnetotelluric method, 3D gravity inversion, The concealed rock mass

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