大地电磁在深部找矿的应用.pdf

2075.77科技论坛大地电磁在深部找矿的应用?飞(安徽省地球物理地球化学勘査技术院,安徽合肥,230022)摘要:大地电磁测深(MT)是地球物理学中地球电磁感应学分支学科中的一种重要方法,它是以天然交变电磁场为场源。不需要大功率的供电设备,因此设备相对轻便;而且不受高阻层屏液的影响,可以深测地下的目标,对低阻层和低阻体反应灵敏。同时大地电磁场的频带也很宽,根据趋肤效应的原理,对应的探测深度就很大.用它可以解决的地质问题就较多,如大尺度地质单元的电磁感应研究,深部地壳地幔电性结构硏究及地壳地壳幔中高导层的检测,地热资源勘查,油气资源普查等。木文以介绍的大地电磁测深法的基木原理、野外工作方法、电磁场的谱分析、噪音的影响和克服等,并以实例来体现大地电磁测深法在深部矿体的寻找中体现出来的独特的优势。关键词:大地电磁测深;视电阻率;趋肤效应Application of electromagnetic depth to prospecting for oreWu I(Anhui Anhui geophysical and Geophysical Exploration Technology Institute, Hefei, 2300Abstract The electromagnetic sounding(MT)is an important method in the field of electromagnetici duc Lion in geophysics, and it is based on the natural al Lornat ing cicciromagnetic ficld. The power supp yequipment is not required, so the equipment is relatively portable and the target is not affected by thehigh resistivity shielding. It can be deeply measured. It is sensitive to the low resistivity and the I owresistivity. And frequency band of the elec Lromagnetic field of the earth is also very wide, the principlef skin offect based on skin, corrcsponding to the probing depth grcat I y. It can solve the gco logical probi cmis more, such as large scale geological unit of electromagnetic induction study and deep crust mantleclectrical dctection of high conductivity Layer in the structure of the crust and crust mant Ic, gcothormaresources exploration, oil and gas resources census. In this paper in order to introduce the magne Lotellurisound ing method basic principlc, ficld working method and clcctromagnctic spectrum anal ysis, the influcncc onoise and overcome, and with examples to reflect the unique advantage embodied in the deep part of the orebodies for magne Lolelluric sounding me thodKeywords: MT; apparent resistivity; skin cffcct0引言勘查和环境保护等,大地电磁测深都可以发挥其独特的优势,大地电磁深测方法的优点是不需要大功率的供电设备,而成为重要的墈查手段。且义有很大的深测深度。由于不需要供电装置,因此设备相对轻1野外工作方法便;再有就是不受高阻层屏蔽的影响,可以深测其下的日标大地电磁测深的野外工作包括选点、布极、观测等内容。我们而且对低阻层和低阻体反应灵敏等。大地电磁场的频带很宽,根观测的是频率为10-4103z的近似平面波的天然电磁场。一切据趋肤效应的原理,对应的探测深度的范围就很大,用它可以无线电波、工业游散电流等都被视为干扰。在工业发达的地区干解决的地质问题就较多,如大尺度地质单元的电做感应研究,扰现象往往特别严重,加之大地电磁场非常微弱,所以严格操作深部地壳地幔电性结构硏究及壳幔中高导层的检测,地热资源方法,有效地避免或抑制干抗、提高原始数据质量对大地电磁测勘查,油气资源普查,天然地震活动前兆监测以及地下水资源甲壬测试143