Geochemistry trace of metallization for polymetal field in Yangjiaba,Lueyang,Shaanxi Province
陕西省略阳县杨家坝多金属矿区成矿作用地球化学示踪

As the example of Yangjiaba polymetallic ore field in Lueyang area, Shaanxi Province, generation of baritite and later silication, carbonatization, talcization, uralitization, sericitization and chloritization and so forth are discovered by analyzing and studying of petrography. With fluorinated achromaite, crypto-crystal siliceous glass and aphanitic kiesel in tremolite, it indicates that hydrothermal fluid which is related to alteration of mineralization is mineralizing fluid, being rich in Si, Fe, Ti and alkali, volatile flux and characteristic of melt mass, which is different from general hydrothermal fluid of crust. The characteristics, as rich in LREE and different assembled abnormity of Ce and Eu and Yb, are found in ore and quartz-calcite veins and volcanic host from polymetal deposits by analyzing and studying their geochemistry of REE, trace element and fluid inclusions. It is concluded that the rich in LREE is one of the obvious characteristics for the action of mantle fluid. Anomalies of positive Eu and negative Ce and Yb in ore and veins and the H2O-C6H6 fluid from fluid inclusion in vein are the important symbols that the mantle fluid has the nature of high temperature and reduction. Existence of anomalies of positive Ce and negative Eu and Ce, Eu, Yb anomalies' weakening and disappearance are an expression as mixing and alteration of crust-mantle fluid. Comprehensive research indicates that poly-metallization is controlled by the mantle fluid being of the natures of high temperature and reduction and rich in LREE under the background of Qinling orogene.Overlying, which causes that the overlying alteration of strong mixing of crust-mantle fluid plays an important role in the poly-metallization.