Discussion on Geological Characteristics and Ore-Controlling Factors of the Yangxie Gold Deposit in Shangluo,Shaanxi Province

Yangxie gold deposit is a medium-sized one located in the eastern section of the Yangxie-Fengbeihe Au-W metallogenic belt, East Qinling.The gold orebodies are mainly composed of gold-bearing quartz veins controlled by NE-NNE and NW-NNW trending faults and hosted in the Neoproterozoic Yangxie gneiss suite in Shangdan fault.Metal minerals in the ore are medium-low temperature mineral associations, and mainly consist of pyrite, native gold, chalcopyrite, tetrahedrite, sphalerite and galena.The process of the hydrothermal ore-forming can be divided into four metallogenic stages:thepotassium feldspar-quartz stage, the quartz-coarse grained pyrite-native gold stage, the quartz-fine grained pyrite-native gold-polymetallic sulfide stage and the carbonate stage.The proximal wall-rock alterations are characterized by potassic alteration, silification and pyritization, while the distal alterations are dominated by chloritization and carbonation. The Yangxie gold deposit is mainly controlled by the faults, the wall-rock and the Indosinian granite;its metallogenic age is no earlier than the Late Triassic.