频率域激电法在广西某金矿区的找矿应用

Application of Induced Polarization Method in a Gold Mining Area in Guangxi Province

广西某金矿区内广泛分布炭质岩,使得矿区整体电阻率偏低,加大了异常体的分布范围,对区分矿致异常及进一步缩小找矿靶区产生了干扰。为了满足深部找矿的勘探要求,在该矿区开展了激电中梯扫面和激电测深等一系列双频激电工作。通过重点把握中、高极化的激电异常区,再结合低阻构造带进行找矿靶区的初步圈定,最后对主要异常区和构造带开展激电测深验证。根据视幅频率和视电阻率确定了4个激电异常区并划分了5条构造带,验证结果表明:1、2号异常区分别与1、2号构造带吻合较好,推测异常是由断裂带或破碎带周边的炭质地层和金属硫化物引起的;3号异常区位于3号构造带与5号构造带相交处,且有向北延伸的趋势,推测异常主要由炭质地层所引起;4号异常区内没有相应构造带的控制,难以对异常源进行合理推断。根据上述勘探结果,圈定了3个地球物理找矿靶区,通过与激电测深反演以及后期的钻探资料进行比较,验证了双频激电法对本金矿区找矿的指导意义,为进一步地质勘探工作提供了科学依据,也为今后开展相关的电法工作提供了思路。

A gold mining area in Guangxi is located in the middle of Dayaoshan ore belt.Due to the exhausted mining of shallow minerals,the gold deposit is faced with the dilemma of resource exhaustion.From 2013 to 2015, relevant departments have successively carried out geological survey in this gold mining area,but these work only focused on the geological phenomena found on the surface,and did not consider the tectonic distribution closely related to mineralization,which could not meet the requirements of deep prospecting. According to the characteristics of high polarizability and low resistivity of metallogenic types in this area,and in order to meet the exploration requirements of deep prospecting,double frequency induced polarization(IP)method was selected to carry out a series of exploration work.The method of this work mainly includes the gradient induced polarization and the IP sound.According to the geological data,the wide distribution of carbonaceous rocks in the area makes the overall resistivity low,which on the one hand improves the probability of finding anomalies and is conducive to the search for gold deposits,on the other hand,increases the distribution range of abnormal bodies and interferes with the differentiation of ore-induced anomalies and the further narrowing of the prospecting target area. In this paper,by focusing on the middle or high polarization IP anomaly areas and combining with the low resistivity structural belt,the preliminary delineation of the prospecting target area is carried out.Then,IP sounding verification is carried out for the main anomaly areas and structural zones. Firstly,four IP anomalies were obtained and five structural zones were divided by the apparent amplitude frequency and the apparent resistivity.The results show that the anomalous No. 1 coincides well with the structural zone No. 1,both of which show a strip-like anomaly along the east-west direction,which is consistent with the predicted main ore tectonic trend. It is speculated that the anomaly is caused by the carbonaceous strata and metal sulfides around the fault zone or fracture zone,and the possibility of gold-bearing deposits in this area is very high.The anomalous No.2 is located in the intersection zone of the structural zone No.2 and the structural zone No.4. It is speculated that there are carbonaceous strata and metal sulfides in this area,and the possibility of gold deposits is high. The anomalous No.3 is located at the intersection of the structural zone No.3 and the structural zone No.5,and tends to extend northward. It is presumed that the anomaly is mainly caused by carbonaceous strata,and the possibility of gold deposits is general.There is no control of the corresponding structural zone in the anomalous No.4 area,so it is impossible to determine the prospecting prospects of the anomaly.According to the exploration results above,3 main prospecting targets were finally delineated.By comparing with inversion of the IP souding and later drilling data,the guiding significance of dual-frequency IP method for prospecting in this gold mining area is verified, which provides a scientific basis for further geological exploration work,and also provides a design idea for carrying out related electrical work in the future.