吉南玄武岩覆盖区水化学异常查证──以两处金矿化的发现为例

INVESTIGATION AND VERIFICATION OF HYDROCHEMICAL ANOMALIES IN THE BASALT-COVERED AREA,SOUTHERN JILIN-EXEMPLIFIED BY THE DISCOVERY OF TWO GOLD MINERALIZED SPOTS

本文通过实例，介绍了吉南玄武岩覆盖区水化学异常查证的化探工作方法。综合研究已有地质条件，认为吉南沿江村、马鹿沟水化学异常地区成矿地质条件有利。结合微景观特点，在沿江异常区２ｋｍ２范围内应用汞气测量圈出区内断裂构造带展布方向。岩石剖面、土壤测量显示出构造经历过热液矿化活动，矿化体埋藏较深。根据土壤测量结果优选出验证靶区。钻探验证结果在地表６２０ｍ以下发现了近３０ｍ厚的Ａｕ矿化体，Ａｕ含量最高１．５ｇ／ｔ。马鹿沟水化学异常区使用水系沉积物测量进行异常追踪，迅速缩小了找矿“靶区”。使用重矿物测量在“靶区”内进一步追踪发现了Ａｕ矿化源。在此基础上经大比例尺土壤测量辅以岩石剖面测量，圈出了一个有望找到火山岩型浅成热液金矿床的成矿远景区。

With practical examples,the present paper has expounded the geochemical prospecting method for investigating and verifying hydrochemical anomalies in the basalt-covered area of southern Jilin.An integrated study of the available geological data shows that geological conditions of the Yanjiangcun and Malugou hydrochemical anomalous districts in southem Jilin are favorable for mineralization.Combined with microlandscape characteristics and applying mercury-vapor survey,the authors delineated the extension of the fault structural zone in an area of 2km2 within the Yanjiang anomalous district.Rock profile and soil survey show that the structure has experienced hydrothermal mineralization and the mineralized body is buried at a rather great depth.On the basis of soil survey,the target area for verification was selected through optimization,and then a gold mineralized body 30m in thickness was revealed by drilling below the depth of 620m,with the highest Au content being 1.5g/T.In the Malugou hydrochemical anomalous district,follow-up for anomaly was conducted by means of stream sediment survey and,as a result,the'target area'for ore prospecting was rapidly reduced. Further follow -up work in the'target area'by means of heavy mineral survey led to the discovery of gold mineralization source.On such a basis,a metallogenic prospect area in which a volcanic epithermal gold deposit is likely to be found was delineated through large-scale soil survey combined with rock survey.