电性源瞬变电磁法在内蒙古多金属矿中的勘查实验

Experiment of Electrical Source Transient Electromagnetic Method in Inner Mongolia Polymetallic Mineral Exploration

摘要: 电性源瞬变电磁法，具有施工方便，探测深度较大，及探测精度相对较高的特点，是目前物探新技术新方法中的研究热点。该方法具有很多优点，在煤炭地质方面已经取得了很大的成就，但在多金属矿床隐伏矿体方面应用的较少。本文基于电性源短偏移距正演程序及全域视电阻率定义，对内蒙某多金属矿进行电性源短偏移距瞬变电磁试验，并采用全域视电阻率定义进行资料处理。试验结果表明，电性源瞬变电磁法，接收位置位于近场，信噪比高。同时根据电性源电磁场有效趋肤深度公式，对时间进行时-深转换，得到不同埋深的视电阻率剖面图，处理结果显示，视电阻率高低阻电性分布，跟重力异常曲线吻合；再结合可控源音频大地电磁反演视电阻率剖面，不仅高低阻位置吻合良好，而且在电性源瞬变电磁的视电阻率剖面上能分辨小构造，岩性分界面明显，说明基于电性源短偏移距瞬变电磁法全域视电阻率定义的资料解释，在金属矿区隐伏矿体勘查的应用是可行的。

Abstract: With the characteristics of convenient construction, large detection depth, and relatively high detection accuracy, the electrical source transient electromagnetic method is currently a research hotspot in new technologies and methods of geophysical prospecting. Because it has many advantages, so it has made great achievements in coal geology, but it is rarely used in the concealed ore bodies of polymetallic deposits. In this paper, based on the short-offset forward modeling program of the electric source and the definition of the global apparent resistivity, the short-offset transient electromagnetic test of a polymetallic mine in Inner Mongolia was carried out. The experimental results show that the receiving position of the tem is in the near field and the signal-to-noise ratio is high. At the same time, according to the effective skin depth formula of the electromagnetic field of the electric source, time-depth conversion is carried out to obtain sections of apparent resistivity of different buried depths. The treatment results show that the distribution of apparent resistivity of high and low resistivity is consistent with the curve of gravity anomaly. Combining of controlled source audio-frequency magnetotelluric inversion of apparent resistivity section, not only position of high and low resistance coincide well, and the electrical source transient electromagnetic can distinguish on the apparent resistivity section of small structure, lithologic interface, that is based on the electrical source short offset transient electromagnetic method the whole domain of the definition of apparent resistivity data interpretation, application in metal mine prospecting concealed ore body is feasible.