Geology Characteristics And Genesis Discussion Of Xiajiadian Gold Deposit In Shanyang,Shanxi Province

The Xiajiadian gold deposit is located in the eastern of the South Qinling metallogenic belt.It is the largest gold deposit in the zone at present,and the ore body is obviously controlled by fault structure.In this paper,the author studies the geological characteristics,geochemical characteristics and fluid inclusions of Xiajiadian gold deposit,and analyzed the ore-controlling factors,physical and chemical conditions and ore-forming material sources of Xiajiadian gold deposit,and compared with the typical Carlin-type gold deposit in China,suggested that the deposit belongs to Carlin-type gold deposit.And put forward the direction of prospecting.The results of geochemical study of rare earth elements in Xiajiadian gold deposit show that the?Eu mean values of ore and surrounding rock?0.74 and 0.79,respectively?are close,and the?Eu mean values are between crust value?0.60?and the upper mantle value?0.79?,which is closer to the upper mantle value,indicating that the ore-forming material has the addition of deep source material.The distribution curve of ore and surrounding rock is basically the same,which indicates that ore-forming material is added in the process of mineralization.The inclusions in quartz and calcite during the principal-element period of Xiajiadian gold deposit are simple,mostly liquid-rich inclusions and a small amount of gas-rich inclusions;The uniform temperature is concentrated between 90-179?and 190-250?,the salinity?Na Cl eqv?range is 0.88-14.98%,its average is5.44%;the density range is 0.749-0.988g/cm³,its average is 0.903 g/cm³.It indicates that the fluid of Xajidian gold deposit is low temperature,low salinity and low density fluid.The ore-forming pressure range calculated from fluid inclusions is3.294-23.866MPa,the average value is 13.815MPa;the ore-forming depth is 0.871-1.864Km,the average depth is 1.381 Km.The results show that the metallogenic characteristics of the Xajidian gold deposit are shallow metallogenic and low-temperature,and it is an epithermal gold deposit.H-O?C-O?S isotope studies show that the range of?¹³C_PDB values is-2.8-1.8‰,the average value is-2‰;the range of?¹⁸O_PDB values is-16.6-13.9‰,the average value is-15.04‰,the range of?¹⁸O_V-SMOW values is 13.38-16.6‰,and the average value is 115.4‰;The?¹⁸O_H2O value is-5.97-14.02‰,the average value is-0.87‰,the?D value is-99-67.6‰,and the average value is-82.77‰;The change range of?³⁴S value of pyrite in principal ore stage is-9.4?5.8‰,and the average value is 0.58‰.It is suggested that the ore-forming fluid of Xiajiadian gold deposit originates from the deep part and is related to magmatic water.The addition of atmospheric water in the late metallogenic period shows that during the upward migration of the ore-forming hot fluid,water/rock reaction occurs with the surrounding rock,carbonate rocks of the surrounding rock formation dissolve,the sulfur of the deposit is a mixed genesis of magmatic sulfur and stratigraphic sulfur.The Xiajiadian gold deposit is the product of the late Jurassic-early Cretaceous large-scale tectonic-magmatic metallogenic events under the background of continental orogeny in Qinling orogenic belt.