The Relationship Between Tectonic-magmatism And Gold Mineralization In Wulong Gold Deposit,liaoning Province

Wulong gold deposit is located about 20km northwest of Dandong City,Liaoning Province.The geotectonic position is located on the northeastern margin of the North China Craton.It is a large-scale gold deposit dominated by quartz veins type and supplemented by silicification altered rocks type.Based on the previous research results,this paper systematically summarizes the relationship between tectonic-magmatism and gold mineralization in Wulong gold deposit through a large number of field investigations and indoor microstructure deformation analysis,zircon U-Pb dating and gold content test.Wulong gold deposit is a typical magmatic hydrothermal vein-shaped deposit,with gold-bearing quartz vein type as the main part and partial tectonic altered rock type.The ore veins are strictly controlled by the fault system,and are closely related to the Early Cretaceous magmatic system in terms of space-time distribution.In terms of tectonic,the structural deformation in the Wulong gold deposit area includes ductile deformation and brittle deformation.And ductile deformation structures are mainly developed in Wulong gneissic granite,and some samples have developed mylonite structures.The Wulong granite zircon U-Pb age is about 165 Ma.The brittle deformation is mainly manifested as a series of parallel NE-trending fault structures and the NNE-trending and NW-trending structures of developed between the NE-trending faults.Gold mineralization is concentrated between Dagudingzi fault and Yangjia fault.The gold-bearing quartz veins and vein rocks occupy the same structural space and generally develop along a set of NNE-trending and NW-trending conjugate fault systems.The gold-bearing quartz veins are relatively stable,the dip is steep,and the parts are nearly upright,showing soothing waves on both plane and profile.Some orebodies are in the shape of a lens,with reappearing and appears beside after disappearing along the dip and strike.Tectonic altered rock type gold mineralization has developed along parts of NE-trending Jixinling fault.Judging from this,NE-trending fault structures not only an ore-guiding structure,but as same as conjugate faults of NNE-trending and NW-trending are both ore-guiding structure,ore-bearing structure.Microstructure studies of mineralization-related rock and ore have shown that the higher the degree of structural fragmentation and the larger the scale,the higher the gold content.The magma systems in the Wulong gold deposit area are mainly the Late Jurassic Wulong gneissic granite,the Early Cretaceous Sanguliu pluton and intermediate acidity dike rocks.The mineralization of the Wulong Gold deposit is closely related to the Early Cretaceous magma.Gold-bearing quartz veins and rock veins occupy the same fault structure space,orebodies are mostly developed inside quartz veins or in the upper and lower parts of diorite veins.The zircon U-Pb dating of the pluton and dike rocks shows that the metallogenic epoch of Wulong gold deposit should be between 128.6-122.56 Ma.The gold elements in granite rocks in the Wulong gold deposit area have a tendency of high content in the near orebody and low content in the far orebody.The difference in gold content between near and far orebody reflects the trend of gold element migration and enrichment in rock masses,and there is a possibility that magmatic rocks in the mining area provide some material sources for gold mineralization.