综合物探方法在六盘山盆地月亮山地区铀矿勘查中的应用

Application of Comprehensive Geophysical Methods in the Uranium Exploration of Yueliangshan Area,Liupanshan Basin

六盘山盆地含有丰富的矿产资源,开展过铀矿找矿工作,曾发现多个铀矿点和铀异常点。由于铀矿具有隐伏性强、成矿地质条件复杂、矿化特征不易发现等特征,给找矿工作带来巨大困难。不同的物探方法可以识别不同的物性差异,利用多种物探方法相结合的勘查手段进行综合分析,给铀矿勘查工作提供重要信息和依据。为进一步研究六盘山盆地月亮山区域成矿条件,基于该地区铀矿地质成矿条件,在前人工作基础上,在该地区重点地段开展了综合物探测量工作。通过开展音频大地电磁法、高精度磁测和土壤氡气测量3种物探测量方法,大致查明了研究区主要断裂的位置、深度和发育特征,确定了基底埋深情况,综合分析区域铀矿化特征和成矿条件。通过音频大地电磁测量和高精度磁测工作,初步确定了研究区内的基底埋深情况,大致查明了研究区主要断裂发育特征;通过高精度磁法测量推断研究区磁异常大小与沉积物厚度相关,盖层越厚,基底越深,其地表磁异常越大;盖层越薄,基底越厚,其地表磁异常越小;通过土壤氡气面积测量,在盆地内部发现了2片土壤氡气异常区。上述结论为后期的地质和钻探工作提供了重要的物探依据。

Liupanshan Basin contains abundant mineral resources.Previous uranium research and exploration in this area have discovered multiple uranium anomalies and occurrences.In order to further study the ore-forming conditions of the Yueliangshan area in Liupanshan Basin,comprehensive geophysical survey work was carried out in the key areas according to the previous achievement on geological and ore-forming conditions of uranium mineralization.By conducting comprehensive geophysical measurement of audio-frequency magnetotelluric method,high-precision magnetic survey,and soil radon measurement,the main faults in the study area were roughly identified in their location,depth,and development characteristics,the burial depth of the basement was determined,and the regional uranium mineralization characteristics and conditions were comprehensively analyzed.The depth of the basement was preliminarily determined by the audio-frequency magnetotelluric and high-precision magnetic surveys,and the main characteristics of fault were roughly identified by using high-precision magnetic measurement.The sediment thickness was inferred by the size of magnetic anomalies,the thicker the cover layer and the deeper the basement were,the greater the surface magnetic anomaly was;while the thinner the cover layer and the thicker the basement were,the smaller the surface magnetic anomaly was;by conducting the areal measurement of the soil radon gas,two abnormal areas were discovered within the basin.The above conclusion provided important geophysical basis for later geological and drilling work.