Geological Characteristics And Deep Prediction Of Zhonghe Silver Polymetallic Deposit In Eastern Xiaoshan

Zhonghe silver polymetallic deposit is located in the east of the Xiaoshan fault uplift,which is connected with the eastern Qinling orogenic belt and the southern margin of the North China Craton.The Xiaoshan area is an important part of the metallogenic concentration area of non-ferrous metals and precious metals of Xiaoqinling-Xiong 'er Mountain,which has superior metallogenic geological conditions.In this paper,the research work of Zhonghe silver polymetallic deposit is carried out in two aspects,namely,the study of the geological characteristics of the deposit and the deep metallogenic prediction.First of all,the study of the geological characteristics of the deposit shows that there is no direct relationship between the strata and the formation of the deposit.The fault structure controls the occurrence state of ore bodies and the development of ore-forming rock mass.The Zhonghe porphyric granite is closely related to the formation of ore deposits.The orebodies are mainly Ag-Pb-Zn and Pb-Zn ore bodies,which appear as stratified.The host rocks in south and north are broken and altered andesites.And the middle is hosted in the ore-forming rocks.The ore structure is mainly vein-reticulate,and the texture is mainly cataclastic.The metallic minerals in the ore are mainly galena and sphalerite,followed by silver-bearing minerals.The gangue minerals are mainly quartz,which can be divided into two metallogenic periods and three metallogenic stages;The alteration intensity of surrounding rock gradually weakens from the fault belt to the sides.The main type of host rock alteration is low-temperature alteration,mainly sericitization and silicification,followed by carbonation,epidote,chloritization,etc.Systematic studies on fluid inclusions and isotope geochemistry of ore deposits show that the ore-forming fluids are dominated by magmatic water,which is characterized by medium-low temperature,low salinity and rich water.The ore-forming fluids and ore-forming materials are mainly derived from the granitic magma partially melted in the lower crust.Combined with previous studies on the Zhonghe granitic porphyry,it is considered that Zhonghe silver polymetallic deposit belongs to medium-low temperature magmatic hydrothermal Ag-Pb-Zn deposit.Secondly,deep metallogenic prediction is also carried out in this study.Under the guidance of metallogenic prediction theory,the deep metallogenic prediction of Zhonghe silver polymetallic deposit is carried out by using 3D geological modeling software and combining with the study of geological characteristics of the deposit.The study of deep metallogenic prediction shows that the construction of comprehensive information prospecting model takes fault structure and Yanshanian acid rock mass as geological prospecting information;the anomaly of apparent polarizability and apparent resistivity as the geophysical prospecting information;The combination anomalies of elements in the former margin halo,near ore halo and tail halo as geochemical prospecting information.In the process of constructing three-dimensional quantitative prediction model,7 kinds of metallogenic prediction factors were extracted from the geological prospecting information of fault structure.2 types of metallogenic predictors were extracted from the metallogenic rock mass.From the geophysical prospecting information,the apparent polarizability ?1.8% and apparent resistivity between 100? 300?·m are extracted as the geological prospecting metallogenic prediction factors.From the geochemical prospecting information,the element combination anomalies of front halo(As-Sb),near halo(Pb-Ag-Au-Zn-Cu)and tail halo(W-Bi-Mo)are extracted as the geochemical prospecting and metallogenic prediction factors.According to the statistical calculation of information quantity method and evidence weight method,there are favorable areas for mineralization in the deep part of the study area,and 9 prospecting targets are delineated based on the predicted information quantity.Class A target area is the optimal target area,which is distributed in the deep part of the existing ore body,with sufficient metallogenic geological conditions and great metallogenic potential.Secondly.B-type target area has good metallogenic potential according to the fault structure and the presumed favorable rock mass for mineralization.Finally,it is the C-type target area with insufficient metallogenic geological conditions and certain metallogenic potential mainly based on fault structure.The prospecting probability evaluation of the prediction results shows that the prospecting probability value is 71.5%,which indicates that the deep prediction results have high credibility.