Geological Characteristics And Genesis Of The Xiaolizi Silver Polymetallic Deposit In Linjiang City,Jilin Province

The geotectonic location of the Xiaolizi silver polymetallic deposit is located in the eastern part of the North China Platform's northern margin(Grade I),the Liaodong platform uprise(Grade II),the rupture of the Taizi River to the Hunjiang River(Grade III),and the northerneast of the Laoling fault block midpiece(Grade IV).And metallogenic conditions are favorable.The exposed stratum in the study area is simple,mainly revealing of the Baifangzi group of the Qingbaikou system in the Neoproterozoic,the fruit pine group of the Jurassic system in the Mesozoic and the Cenozoic strata.The main faults in the study area are NE-trending and NW-trending,which are closely related to mineralization.The magmatic activity in the area is relatively strong,mainly the Yanshanian meta-neutral andesite,acid andesite,granodiorite porphyry,and quartz diorite porphyry,of which acid andesite is widely distributed.Among them,acid andesite,granodiorite porphyry and quartz diorite porphyry are closely related to silver polymetallic mineralization.The main metal minerals of Xiaolizi silver polymetallic deposit are pyrite,chalcopyrite,porphyry,galena,sphalerite and magnetite,which account for 10%-40%in the ore minerals.The ore texture is relatively complex,such as automorphic-semi-automorphic or other-automorphic crystal texture,metasomatic etching texture,solid solution separation texture,fragmental porphyry texture,fragmental texture and so on.The ore structure in the area is relatively complex,with disseminated structure,network vein structure and breccia structure as the main structure,followed by mass structure.The wall rock alteration mainly includes silicification,carbonation and chloritization,and all of them are near the orebody wall rock alteration.Due to the intrusion of late quartz diorite porphyry,the alteration and metasomatism of the orebody and surrounding rocks are obvious,forming altered rocks of several meters to tens of meters,which are closely related to mineralization.The study of fluid inclusions in the main metallogenic stage shows that the type of mineral fluid inclusions in Xiaolizi silver polymetallic deposit is simple.It is a gas-liquid two-phase inclusion.The density of ore-forming fluid is concentrated in the range of 0.80-0.92 g/cm~3.The ore-forming temperature is concentrated in the range of216-324 degree celsius,the ore-forming pressure is 17.02-36.29 MPa,and the ore-forming depth is 1.70-3.63 km.Based on the analysis and summary of geological characteristics and mineralization physicochemical conditions of Xiaolizi silver polymetallic deposit,it is considered that Xiaolizi silver polymetallic deposit is a shallow mesothermal vein deposit.