Geological,Geochemical Characteristics And Metallogenic Mechanism Of The Jinchanggouliang Gold Deposit In Aohan,Inner Mongolia

The Jinchanggouliang gold deposit is located in the eastern section of the Zhangjiakou-Chifeng first-grade gold metallogenic belt on the northern margin of the North China Craton.Through detailed field surveys and indoor comprehensive research,this paper considers that the metamorphic rock series of the Xiaotazigou Formation in the Jianping Group of the Upper Archean is the ore-bearing surrounding rock of the deposit.The ore-bearing structure is a fault structure in the northwest and north-south directions,and there are northeastward ore-bearing faults in some areas.The type of ore is mainly quartz vein type and less altered rock type.Metal sulfides include pyrite,chalcopyrite and galena.Gold minerals are mainly natural gold and silver gold.The non-metallic minerals are dominated by quartz,followed by chlorite and calcite.The ore structures mainly include disintegrated structures,he-shaped gap-filling structures,and emulsion droplet structures.The ore structures mainly include massive structures,belt-like structures,and vein-like structures.Wall rock alterations mainly include silicification and pyrite transformation.The ore mineralization process can be divided into three stages.The face-mug compound rock mass closely related to mineralization has geochemical characteristics similar to adakitic rocks and is a highly-differentiated I-type granite.It is partially melt-mixed to form adakite magma from mantle-derived magmatic intrusion.It evolved as a product of the stretch of land after the late Jurassic orogeny.The development of rhyolite porphyry after the mineralization period is more complicated,but the overall performance is more consistent.It may be due to the strong separation and crystallization of mantle-derived magma and crust source material during the crust-mantle interaction process.It belongs to Early Cretaceous.The product of stretching the environment in the land.The study of fluid inclusions in the deposit shows that the ore-forming fluid belongs to the medium-high temperature,high salinity,low-density H₂O-NaCl system.The immiscible?boiling?effect of the fluid is the main mechanism of mineral precipitation and the deposit is formed in the medium-depth.Into the environment.Isotope studies indicate that the ore-forming fluids are dominated by magmatic water,and there is partial participation of atmospheric precipitation in the later period.The metallogenic material mainly comes from the deep magmatic activity,namely the compound rock body of opposite groove.Based on the above research,this paper considers that the genesis type of gold deposit in the gold plant is a medium-high temperature hydrothermal vein type gold deposit related to magmatic action,and the metallogenic age is between 136 Ma and131 Ma.The formation environment of this deposit is an intracontinental extension environment.The direct dynamic background is the combined effect of mantle-derived magmatic intrusion and lithospheric de-settlement.