Geological Characteristics And Metallogenic Model Of Huangzhuyuan Silver Polymetallic Deposit In The Luzong Volcanic Basin,Anhui Province

Epithermal deposit is an important type of Au,Ag precious metal deposits in the world.A large part of the large Au,Ag precious metal deposits and non-ferrous metals deposits such as Pb,Zn,Cu are epithermal deposits.However,the study on the genesis of these deposits is not deep enough.The Huangzhuyuan silver polymetallic deposit is a small epithermal silver polymetallic deposit newly discovered in Luzong volcanic basin in the middle and lower reaches of the Yangtze River.It is the first epithermal silver polymetallic deposit discovered in the basin.The research on it can perfect and supplement the metallogenic type in the ore concentration area Based on the geological exploration data of the deposit,this paper focuses on the carefully field work and systematic petrography and mineralogy of the deposit and combined with short wave infrared analysis,electron microprobe testing,cathodoluminescence and geochemical characteristics of quartz,studied the alteration and mineralization characteristics and the genetic types of the deposit.Based on the preliminary established the Huangzhuyuan deposit metallogenic model.Through the research work,mainly obtained the following results:Through the field drilling observation,it is found that the host rocks of different types of orebodies are different,in which the low-grade Cu orebodies are mainly developed in Zhuanqiao formation and the Cu-Ag orebodies are mainly developed in Shuangmiao formation,and the elements have certain zonation.Through the analysis of short wave infrared spectrum,it is found that the main alteration mineral assemblage includes K feldsparization,silicification,carbonation,sericite-illitization and kaolinite-montmorillonization.Find out the mineral composition of the deposit by SEM and EMPA,and according to the paragenetic association and interpenetration relationship of minerals,the metallogenic process of the deposit is divided into three metallogenic stages including sulfide-barren quartz vein stage;quartzsilver minerals-sulfides vein stage;quartz-calcite vein stage.The quartz silver mineral sulfide vein stage is the main metallogenic stage,which can be divided into chalcopyritepyrite-specularite combination;the chalcocite-bornite-Silver minerals combination and digenite-covellite combination.Through TESCAN Integrated Mineral Analyzer to analysis Silver and key metal minerals,it is found that The main Silver minerals in the deposit are silver,stromeyrite and danielsite,which are developed in irregular granular or dendritic shape at the edge of chalcocite or wrapped in chalcocite;the key metal minerals in the deposit are mainly cobaltite and glaueodot,which are distributed in the edge of chalcocite and pyrite in an irregular granular manner.Both Silver minerals and key metal minerals are only developed in vein and disseminated oresThe cathodoluminescence photographs of quartz in different metallogenic stages show that the quartz in sulfide-barren quartz vein and quartz-calcite veinis in the form of microcrystalline aggregate,and the growth ring can not be observed;the quartz in quartzsilver minerals-sulfides vein is in the form of hexagonal plate or short column,and the obvious growth ring and fracture can be observed.Trace element analysis of different types of quartz in the three metallogenic stages indicates that the mineralization in the deposit was formed in the process of increasing p H value.The ore-forming fluid is characterized by the transition from porphyry deposit to high-sulfur epithermal deposit,and the metallogenic temperature is initially defined as 250?400?.The variation of Al,K and Cu in quartz reflects the pulse behavior of ore-forming fluidBased on the comparison of geological characteristics such as alteration and mineralization and quartz trace element characteristics with typical deposits in the world,it is considered that the Huangzhuyuan deposit is a high sulfur epithermal deposit superimposed on the porphyry deposit.Through the establishment of the spatial and genetic relationship between the Huangzhuyuan deposit and the Qianpu lithocap,it indicates that there may be a large porphyry-epithermal system in this area,which is an important target area for deep prospecting in the Luzong basin...