Comparative Study On Geochemical Characteristics Of Linglong Gold Deposit And Jiaojia Gold Deposit In Jiaodong

The gold deposit area of Jiaodong Peninsula is one of the main gold producing areas in China.The main types of deposits are altered rock type and quartz vein type.However,gold ore-forming fluids and material sources in the area have been controversial.In this study,a detailed comparative study of detailed fluid encapsulation characteristics and isotope geochemistry was carried out for two types of typical gold deposits,and the ore-forming rules were summarized.Quartz vein type Linglong gold deposit and altered rock type Jiaojia gold deposit are two typical deposits in this area.Altered rock type and quartz vein type gold deposit are distributed in two mining areas,but the dominant position is different.The fluid inclusion test found that the ore-forming fluid of the quartz vein type Linglong gold deposit gradually cooled down and decreased salinity in the first stage to the fourth stage,while the ore-forming fluid of the altered rock type in the Jiaojia gold deposit area had a warming phenomenon in the second stage.There are cooling phenomena in the four stages.The main and trace element characteristics of pyrite in ore minerals show that the value of ?Eu value in Linglong gold deposit is larger than that of Jiaojia gold deposit(0.87),and the ore-forming environment of Jiaojia gold deposit is more reductive than that of Linglong gold deposit.The characteristics of Sr-Nd and S isotopes in pyrite show that the Linglong gold deposit is consistent with the ore-forming source area of Jiaojia gold deposit,and is mainly composed of shell source,and a small amount of mantle components are added.The H-0 isotope characteristics show that metamorphic water and magmatic water are the main sources of ore-forming fluids,and a small amount of atmospheric water is added.The comparison between quartz vein type Linglong gold deposit and altered rock type Jiaojia gold deposit shows that metamorphic water and magmatic water are the main sources of ore-forming fluid,the difference is that atmospheric precipitation contributes more to altered rock type ore-forming fluid.In the late Mesozoic,the lithospheric mantle in the eastern North China Craton was enriched by the subduction of the ancient Pacific plate source fluid,and then the hydrothermal-mechanical erosion of the lithospheric mantle was partially melted due to the withdrawal of the subduction plate.And form a helium source fluid containing CO2.The CO2 lanthanum source fluid reacts with the surrounding rocks of Guojialing granite and Linglong granite during the upward movement.Due to the sudden increase of the structural space of the ore-forming fluid,the pressure is reduced,the boiling point of the fluid is lowered,and the fluid is boiled and unmixed.Solubility causes large-scale precipitation of gold;when atmospheric water begins to mix into the ore-forming fluid,the fluid temperature is further reduced and the mineralization enters the end.The fluid forms an altered rock type Jiaojia gold deposit when entering the compression-torsion fault zone,and forms a quartz vein type Linglong gold deposit when entering the torsional fracture zone.