九瑞矿集区三维电性结构研究及找矿意义  

Three-dimensional electrical structures and significance for mineral exploration in the Jiujiang-Ruichang District

作　　者：邓居智[1] 陈辉[1,2] 殷长春[2] 周彪华 

机构地区：[1]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 [2]吉林大学地球探测科学与技术学院,长春130026

出　　处：《地球物理学报》2015年第12期4465-4477,共13页Chinese Journal of Geophysics

基　　金：深部矿产资源立体探测技术与试验(SinoProbe-03-03);十二五国家科技支撑计划(2011BAB04B03);国家自然科学基金项目(41164003;41404057)联合资助

摘　　要：九瑞矿集区作为全国重点整装勘查区之一,深部找矿工作一直是研究重点和热点.本文在综合分析研究区区域地质资料、对典型地层和岩石标本进行电阻率参数测试和统计分析的基础上,利用研究区面积性AMT数据进行三维电性结构研究.为获得AMT最佳反演参数,选择一条典型AMT剖面开展二维非线性共轭梯度(NLCG)反演,进而总结出利用TM极化模式数据、拉格朗日乘子等于3的二维反演方案.综合利用地质、钻探和电性特征对全区23条AMT剖面进行二维约束反演,并将所有测线的电阻率反演结果三维网格化,得到了研究区的三维电性结构.最后,我们通过对三维电性结构的综合分析,确定研究区地下地层、岩体展布、断裂构造分布特征以及基底起伏情况.与已知矿床对比,我们发现浅部北西断裂与北东向区域性深部断裂交汇处、基底隆起凹槽边缘以及岩体边缘为成矿有利区.The Jiujiang-Ruichang district is one of the most important Cu-Au ore deposits in the Middle-Lower Yangtze metallogenic belt of eastern China,as well as one of the integrated exploration zones in China.In the past geological exploration has found shallow subsurface metallic ore deposits,and the prospecting for deep deposits is the present emphasis in this region.The objective of this work was to detect the three-dimensional electrical structures from AMT surveys,which provide information for prospecting of deep deposits in the Jiujiang-Ruichang district Firstly,we examined the characteristics of the regional geology,tectonics and magmatic rock.We conducted statistical analyses of the stratigraphic and lithologic resistivities with measurements of 1125 rock samples.Secondly,we collected audio magnetotelluric（AMT）data over a 23km×20km area in the Jiujiang-Ruichang district,which included 23 profiles orientedNS,each 20 km in length and 1km in width using frequencies ranging from 0.35 Hz to 10400 Hz.We implemented two-dimensional（2D）non-linear conjugate gradient（NLCG）inversion with TM mode data using a Lagrange multiplier of 3for the whole Jiu-Rui metallogenic district.Finally,by integration and 3D gridding of the 2Dinverted resistivity data,we established 3D electrical structures for the total of the 23 AMT profiles.The results show the formation distribution,the regional structures,and the 3Dundulating basement as well as the location of magmatic vents.After comparing the results with the known deposits at the Jiu-Rui metallogenic district,we found that the prospective areas of mineralization are located in the places where shallow NW faults and deep NE faults cross,the groove edges of the basement are uplifted,in addition to the margins of magmatic rocks.

关 键 词：九瑞矿集区 音频大地电磁法 电性结构 三维 深部找矿 

分 类 号：P631[天文地球—地质矿产勘探]