STUDY ON THE FLUID INCLUSIONS OF NANLONGWANGMIAO GOLD DEPOSIT IN QINGYUAN, LIAONING PROVINCE

The Nanlongwangmiao gold deposit is occurred in the northeast of Qingyuan Group supracrustal rocks in the northern margin of North China Craton. The main host rock is Neoarchean magnetite quartzite with Hulutougou-Dahanggou ductile shear zone as the ore-controlling structure. The ore is veinlet-disseminated structure dominated with the main alteration types of muscovitization, silicification, chloritization, carbonatization and epidotization. The analysis results on the petrography and microthermometry of fluid inclusions in the veinlet-disseminated quartz ore show that there are two stages of fluid inclusions. The early stage forms the daughter mineral-bearing three phrase inclusions (I); while the later stage involves the gas-liquid inclusions (II), pure CO₂ inclusions (III) and CO₂-bearing three phase inclusions(IV). The course of fluid evolution is as follows:The early-stage fluids with medium temperature, high salinity and intermediate density extract Au from the supracrustal rocks of Qingyuan Group, and then turn into moderate-low salinity and low density during the transformation of shear zone from ductile to brittle deformation at the later stage. The Au element reaches saturation and precipitates in favorable structural space to form deposit. The mineralization gradually changes from diffusion metasomatism to filling, forming veinlet-disseminated and gold-bearing pyrite quartz-vein orebodies respectively.