辽宁凤城白云金矿带地质特征、矿床成因及找矿方向

Geological Characteristics,Ore Genesis and Prospecting Direction of Baiyun Gold Belt in Fengcheng City, Liaoning Province

白云金矿带位于华北地台北缘辽东吉南古元古代裂谷中段,裂谷发育晚期形成的黏土质半黏土质岩石组成的碎屑岩沉积建造为含金建造。该矿带为国内著名的辽东青城子铅锌金银矿集区内的重要金矿带,矿带内已发现了1#、2#、10#、11#、60#、70#、80#、90#8条规模较大的金矿脉带,每条矿脉带由数条或数十条金矿体组成,累计探获资源储量金约80t、银400t。对白云金矿带的成矿地质特征、矿脉带及矿体特征、矿床微量元素及稀土元素特征等进行了详细研究。结果表明:①白云金矿带赋存于古元古界辽河群盖县组片岩中,盖县组片岩不仅是重要的矿源层,也是金矿容矿岩石;②金矿带受近EW向白云推覆构造带控制,推覆构造作用于横向以及垂向上形成的平行产出的层间断裂群,控制着金矿脉带的空间展布;③硅化、钾化与金成矿关系密切,矿化类型以硅钾蚀变岩型为主,次为石英脉型,金矿床成因类型为沉积变质岩浆热液改造型。在上述分析的基础上,通过对以往找矿突破的勘查思路及找矿勘查成果的系统研究,总结出了盖县组片岩、韧脆性剪切带、层间断裂群、中性及中酸性岩脉、硅钾蚀变带5条找矿准则,其中“盖县组片岩+层间断裂群”为寻找深部隐伏矿体的关键准则,并提出了400~800m埋深、800 m以深、矿带东西两端延长部、白云推覆构造的主构造面深部是今后找矿的重点区段。

Baiyun gold belt is located in the middle part of Liaodong-Jinan Paleoproterozoic rift in the northern margin of North China Platform.The gold-bearing layers are clastic sedimentary formations which are made up of clayey and semi-clayey rocks at the late stage of rift development,and they are very important gold belts in the well-known Qingchengzi lead-zincgoldsilver mining area in Eastern Liaoning Province.Eight large-scale gold vein belts have been found in the gold belt named as 1#,2#,10#,11#,60#,70#,80#and 90#.Each vein belt is made up of several or dozens of gold orebodies.The cumulative explored reserves in the gold belt are about 80 tons of gold and 400 tons of silver.The metallogenic characteristics,characteristics of ore vein belt and orebody,trace and rare earth elements characteristics of Baiyun gold belt are studied in depth.The results show that:①the gold belts are located in the schist of Gaixian Formation,Liaohe Group of Paleoproterozoic Erathem,and the schist is not only an important source layer but also the host rock of gold deposit;②the gold belt is controlled by the approximately east-west Baiyun nappe structural belt,the interlayer faults that are formed transversely and vertically by nappe tectonics control the spatial distribution of the gold vein belt;③the gold mineralization is closely related to the alteration of silicification and potassiumation,the type of mineralization is dominated by silicon-potassium altered rocks,followed by quartz veins,the genetic type of gold deposit is deposition-metamorphism-magmatic hydrothermal reformation.Based on the above analysis results,through the comprehensive study of the previous results of prospecting and exploration,five prospecting norms such as the schist of Gaixian Formation,ductile-brittle shear zone,interlayer fault groups,neutral and medium-acid veins,silicon-potash alteration zone are summarized,and the double norm of“Gaixian Formation schist+interlayer fault group”is the key to search for the deep concealed deposits,besides that,key ares for the further prospecting in the area can be concluded that the embedded depth of 400~800 m,the depth beneath 800 m,the extensions at the east and west ends of the ore belt and the depth of the main structural plane of Baiyun nappe structure.