音频大地电磁测量在新疆白杨河矿区花岗斑岩侵入体探测中的应用

Application of Audio Frequency Magnetotelluric survey in the exploration of granite porphyry body in Baiyanghe mining area of Xinjiang

新疆雪米斯坦火山岩带白杨河矿区铀铍矿共生,花岗斑岩与上泥盆统凝灰岩的接触带是主要容矿部位,通过常规的钻探方法直接查明接触带展布形态存在很大困难。钻孔测井电阻率统计结果表明,在花岗斑岩与凝灰岩之间存在较为明显的电阻率差异,通过开展音频大地电磁测量,在反演电阻率断面图上花岗斑岩表现出与凝灰岩迥异的等值线形态面貌,推断花岗斑岩侵入体呈残留的岩盖形式,北薄南厚,最大厚度达200 m,花岗斑岩与凝灰岩接触带的埋深自北向南逐渐增大。钻探结果表明,推断结果与实际情况吻合较好,音频大地电磁测量取得了较好的应用效果,达到了快速、经济、准确的预期目的。

There is a uranium-beryllium deposit at Baiyanghe mining area in Xuemistan volcanic belt,Xinjiang,and the main ore-bearing bodies are hosted in the contact zone between granite porphyry and Upper Devonian tuff.It is very difficult to find out the distribution feature of the contact zone directly by the general drilling method.The statistical result of drillinghole logging resistivity ratio shows that there is an obvious resistivity difference between granite porphyry and tuff.Through Audio Frequency Magnetotelluric survey,granite porphyry shows a very different isoline appearance from tuff on the resistivity ratio inversion profile.It is inferred that the granite porphyry body is in the form of residual rock cover,which is thinner in the north and thicker in the south,with a maximum thickness of 200 m.The buried depth of the contact zone between granite porphyry and tuff increases gradually from the north to south.The drilling result shows that the inferred conclusion is in a good agreement with the actual situation,and the Audio Frequency Magnetotelluric survey has achieved a good application effect to attain the expected purpose of rapid,economical and accurate identification.