等值反磁通瞬变电磁法在个旧市某矿井巷道找矿中的应用

Application of Opposing Coils Transient Electromagnetics in Mine Roadway Prospecting in Gejiu City

矿井地球物理方法超前探测要求准确探测巷道下未知面地质异常体,探测空间小,干扰大,技术要求高。为了研究等值反磁通瞬变电磁法(OCTEM)对个旧市大屯锡矿某矿区超前探测的效果,在矿区巷道的底面针对矿山中各类型矿体、断裂构造等布置了两条测线进行实验。通过两条测线的结果和已知的地质资料和后续钻孔资料对比可知,在OCTEM的反演电阻率剖面中,呈现低阻凹陷,且趋势较连续的区域,可推断为断裂、构造破碎带等;出现相对低阻且等值线闭合或呈低阻的小凹陷,该处可圈定为低阻异常区域,结合已知地质资料和钻孔验证结果确定此处低阻异常区为电气石较富集区域。可见,OCTEM对个旧市某矿区井下探测效果较好,能够确定断层、破碎带、含金属矿区的基本位置,为后续在该矿区寻找花岗岩次级凹兜提供了新勘探方法,可以在该矿区或类似矿山开展超前探测工作。

The advance detection of mine geophysical methods requires accurate detection of unknown geological anomalies beneath the roadway, with small detection space, large interference, and high technical requirements. In order to study the effect of Opposing coils transient electro magnetic (OCTEM) on advanced exploration of a certain mining area in Datun Tin Mine, Gejiu City, two survey lines were arranged at the bottom of the mining roadway for experiments on various types of ore bodies and fault structures in the mine. By comparing the results of the two survey lines with known geological data and subsequent borehole data, it can be seen that in the inversion resistivity profile of OCTEM, areas with low resistance depressions and relatively continuous trends can be inferred as faults, structural fracture zones, etc.;a small depression with relatively low resistivity and closed contour lines or low resistivity can be delineated as a low resistivity anomaly area. Combining known geological data and borehole verification results, it is determined that the low resistivity anomaly area here is a relatively rich area of tourmaline. It can be seen that OCTEM has a good effect in underground exploration of a mining area in Gejiu City, which can determine the basic location of faults, fracture zones, and metal bearing mining areas, providing a new exploration method for the subsequent search for granite secondary pockets in the mining area, and can carry out advanced exploration work in the mining area or similar mines.