大地电磁数据三维反演技术在隐伏断裂勘察中的应用：以郯庐断裂宿迁段为例  

Application of 3-D Inversion Method of AMT Data on the Detection of Hidden Faults in the Near-surface Structure: An Example from Tan-Lu Fault Zone

作　　者：罗旭[1,2] 毛星[1,3] 魏文博[1,2] 叶高峰[1,2] 金胜[1,2] 尹曜田[1,2] 

机构地区：[1]地下信息探测技术与仪器教育部重点实验室(中国地质大学·北京),北京100083 [2]中国地质大学,地质过程与矿产资源国家重点实验室,北京100083 [3]中铁第五勘察设计院集团有限公司,北京102600

出　　处：《现代地质》2016年第3期587-596,共10页Geoscience

摘　　要：应用音频大地电磁测深法(AMT)对郯庐断裂宿迁段隐伏断裂进行勘察研究,共布设3条AMT剖面,获得61个测深点,并对所获得的AMT数据进行电性主轴分析和维性分析,采用二维反演和三维反演算法,得到了可靠的地电模型。通过基于阻抗张量Groom-Bailey分解方法的电性主轴分析得到,从浅部到深部,电性主轴方向较为一致,约N60°E,这与浅层地质填图资料略有不同(浅表地质资料显示断裂走向约N20°E),这一角度推断为郯庐断裂主断裂或者其分支在地下的走向。应用基于相位张量分解的维性分析,得到郯庐断裂宿迁段在部分深度范围内表现出一定的三维特征,因此单纯采用传统的二维反演方法不能够准确反映地下构造信息,需要同时采用二维反演方法与更先进的三维反演方法对其进行建模来研究隐伏断裂带的产状信息。通过二维反演和三维反演结果对比看出,三维反演能全面反映断裂带的倾向、走向、延伸深度等信息,反演模型更为可靠。最后把三维反演模型垂直切片和水平切片分别与放射性元素探测剖面测得的氡元素异常曲线对比,也得到很好的对应。综上所述,大地电磁数据维性分析和电性主轴分析在隐伏断裂勘查中是非常必要的,对于复杂异常体,三维反演比二维反演能更加全面可靠地反映构造信息。In this paper the AMT method was applied to study the concealed faults of Tan-Lu Fault zone in Suqian, Jiangsu Province. Three AMT profiles had been deployed which included 61 AMT sites and the electrical strike and its dimension were analyzed with these data. By conducting traditional 2-D and advanced 3-D inversion methods, the reliable underground geoelectric models were obtained. The geoelectric strike direction of the sites near the fault derived from GB decomposition is about to N60°E from shallow to deep, which is inferred to be the strike of main fault or branch fault, and is slightly different from that derived from the shallow geological mapping （~N20°E）.Then based on the phase tensor analysis result, the dimension data near the fault show 3-D features in some depths. The 3-D inversion method can provide more reliable models of the concealed fault and comprehensively reflect the information of fault tendency, extending depth and other features, so 3-D inversion method is more reliable than the traditional 2-D inversion method.In addition, the location of the fault obtained from the 3-D inversion model matches well with that inferred from radioactive element detection. In conclusion, the geoelectric strike and dimension analysis for electromagnetic data are necessary in the exploration of concealed faults, and the 3-D inversion method can get more reliable resistivity models for concealed faults than the 2-D inversion method.

关 键 词：音频大地电磁测深法 三维反演 维性分析 电性主轴分析 郯庐断裂 

分 类 号：P631[天文地球—地质矿产勘探]