Geological Structure Characteristics And Genesis Of Silver Polymetallic Deposits In The Nuwentingtun Area,Inner Mongolia

The Derbugan metallogenic belt is located in the eastern part of the Central Asia Mongolia geosyncline fold area between the North China paraplatform and the Siberian Platform.It is an important Au,Ag,Cu,Mo,Pb,Zn metallogenic belt in the northeast of China.Nuwentingtun silver polymetallic deposit is located in the southwest of the Derbugan metallogenic belt,which is an important prospecting breakthrough in recent years.It has important theoretical and practical significance for the exploration and genesis of the deposit in the southwest of the metallogenic belt.The grade I ore controlling structure of the nuwentingtun silver polymetallic deposit is a deep fault in the NE direction of the Derbugan.The ore body is mainly controlled by the NE and NW faults in the mining area.The two faults converge into a grid structure pattern,and the main ore body occurs at the intersection of NE and NW faults.The strata in the mining area are mainly rhyolite,tuff of Upper Jurassic manketou OBO formation,andesite and coarse andesite of manitu formation;magmatic activities are developed in the area,and the intrusive rocks are mainly granite porphyry and rhyolite porphyry.The ore body is mainly located in the contact zone of granite porphyry and rhyolite and tuff of manketou OBO formation.The ore type is manganese silver type ore and quartz vein type ore.the surrounding rock is developed into silicification,carbonation,fluoritization,pyrite and kaolinization.Through the analysis of the results of surface trenching and deep drilling in the nuwentingtun mining area,it is found that the ore body is enriched in surface layer of the earth's surface,the grade of the ore body is rapidly reduced from the surface down,and the ore body is rapidly pinched out.The fluid inclusions of quartz vein type ore show that the ore-forming temperature is 186-368?,with an average of 289?.The characteristics of S and H,O isotopes show that the ore-forming materials are mainly from deep magma,and the ore-forming fluid is a mixture of magmatic hydrothermal fluid and atmospheric precipitation.It can be concluded that the nuwentingtun silver polymetallic deposit is a epithermal deposit related to granite porphyry.The zircon U-Pb age of the granite porphyry in the mining area is 153.08±0.96 Ma,so the mineralization of the deposit occurred in the late Yanshan.