二连盆地哈达图铀矿床综合物化探特征及找矿意义

Comprehensive Geophysical and Geochemical Characteristics of the Hadatu Uranium Deposit in Erlian Basin and Their Prospecting Significance

二连盆地哈达图铀矿床是我国大型可地浸砂岩型铀矿床,矿体埋深大、品位富,研究其地电化学等综合物化探特征,可为建立覆盖区航放异常有效查证技术方法提供依据。基于矿床地质及航磁航放特征的分析,开展组合物化探方法测量及特征分析。研究表明:哈达图铀矿床位于受断裂构造控制的北东向、北北东向中等磁场区及中等-弱磁场的梯度带;航空及地面伽马能谱U含量垂直于矿体走向“两边高、中间低”,且矿区及矿体的航空伽马能谱U含量的熵值相对较大;矿体上方的地电化学U异常主要为深部铀矿体的纳微米级铀矿物垂向迁移至近地表被土壤中粘土矿物吸附所引起;埋深大于300 m的铀矿体仍具有地电化学U高、Mo低的平面特征,在剖面上U含量呈锯齿状尖峰异常;矿体对应于土壤氡浓度低值区。地电化学、地面伽马能谱、土壤氡浓度的组合测量技术能够有效查明覆盖区航放弱信息的成因及其与深部铀矿体的空间关系,可为隐伏砂岩型铀矿找矿有利地段的圈定提供依据。

The Hadatu uranium deposit in Erlian Basin is a large-scale in-situ leachable sandstone-type uranium deposit in China,with a large burial depth and high uranium ore grade.It is of great significance to study the comprehensive geophysical and geochemical characteristics of this deposit,which will help to establish an effective method for the verification of airborne anomalies in coverage area and to improve the exploration effect of hidden uranium deposits.This work is based on the geological,aeromagnetic and airborne radiometric features of the deposit to conduct combined geophysical and geochemical survey and analysis.The results show that the Hadatu uranium deposit is located in the NE-trending and NNE-trending medium magnetic field and medium-weak magnetic field gradient zone controlled by fault structures.The U content of aerial and ground gamma energy spectra is high on both sides and low in the middle,which is vertical to the strike of the ore body.The airborne gamma spectrum uranium content above the deposit has high entropy.The geoelectrochemical uranium anomaly above ore body is mainly caused by the vertical migration of nano-micron uranium mineral from deep uranium ore body to the near surface and adsorption of clay minerals in the soil.The geoelectrochemical uranium of the deposit has a saw-tooth spike anomaly on the profile,and the plane is characterized by high uranium and low molybdenum.In addition,uranium ore bodies with a burial depth of more than 300 m still have geoelectrochemical anomalies.The soil radon concentration above orebody is relatively low.Combined measurements of geoelectrochemistry,ground gamma spectroscopy and soil radon concentration can effectively identify the cause of weak airborne information in coverage area and its spatial relationship with deep uranium ore bodies.This comprehensive method can provide a basis for the delineation of favorable areas for concealed sandstone-type uranium deposits.