大地电磁测深不同极化模式测深曲线特征在探测断裂中的应用  

Application of curve features under different polarization modes of magnetotelluric sounding in the detection of faults

作　　者：李尔頔 罗润林[1] 徐志锋[1] 

机构地区：[1]桂林理工大学地球科学学院,广西桂林541004

出　　处：《矿产与地质》2017年第1期124-130,共7页Mineral Resources and Geology

基　　金：2014年广西自然科学基金项目(编号:2014GXNSFAA118305)资助

摘　　要：大地电磁测深数据包含TE和TM极化模式信息。在二维地层结构条件下,这两种极化模式获得的ρ_(xy)、ρ_(yx)视电阻率曲线特征及相互关系与地下电性结构有关。当低阻体或断裂等地质构造存在时,两种曲线存在明显的组合规律。在探测深大断裂工作中,综合利用两种模式的视电阻率曲线及其组合规律信息,可以排除浅部低阻体的影响,确定隐伏断裂的位置。本文研究了浅部低阻体和断裂地层结构模型的ρ_(xy)、ρ_(yx)视电阻率曲线特征及变化规律,并将其用于深大断裂处的实测大地电磁测深资料的解释,地质效果较好。理论研究和实例验证说明利用ρ_(xy)、ρ_(yx)视电阻率曲线的特征可以为大地电磁测深资料解释提供有效的参考信息。Magnetotellurie sounding data contain the information of TE and TM polarization modes. The characteristics of the ρxy and ρyx apparent resistivity curvesarelinked to the underground electrical structure under the conditions of 2D formation structure. The two kinds of curves are apparently characterized by combination regularities whilegeological structures like low resistivity bodies or faults exist. In the detection of deep fractures, the influence of the low resistivity bodies can be excluded, and the location of concealed fractures can be determined by taking advantage of apparent resistivity curves and its combination regularities of the two modes. This paper explored the ρxy and ρyx apparent resistivity curve characteristics of structure models of low resistivity bodies and fracture formations in shallow part and their variation regularities, and the results were used to explain the magnetotelluric sounding data acquired from deep fractures. Good geological results were achieved. Theoretical and experimental case studies show that the characteristics of the ρxy and ρyx apparent resistivity curves can provide effective reference information for the interpretation of magnetotelluric sounding data.

关 键 词：大地电磁测深 断裂探测 TE模式 TM模式 

分 类 号：P631[天文地球—地质矿产勘探]