Abstract:

The Shuangwang gold deposit is located in the southwest of Taibai County, Shaanxi Province. It occurred in the Devonian strata of the Qinling orogenic belt. Systematic fluid inclusion study of hydrothermal minerals from No8, 7, 9, 5, 6 and 2 ore bodies shows that the inclusions of the Shangwang gold deposit had diversity of characteristics. The range of homogenization temperature of inclusions in early oreforming stage, main oreforming stage and late oreforming stage are from 300 to 463 ℃, 220 to 340 ℃, and 100 to 279 ℃ respectively. The characteristics of main oreforming stage fluid are low salinity content (21%-227% NaCl eqv), rich in CO2 and containing N2, CH4 and other gases. From east to west, the trapping pressure is gradually decreasing, and the open fluid system tends to be dominant. Mineralizing fluids were mixed fluids which mainly originated from magmatic and metamorphic water. At the later stage, some meteoric water joined into the fluid system. The diversity and evolution of fluid inclusions and a large number of breccia ores indicate that oreforming fluids of the Shuangwang gold deposit have the characteristics of fluid unmixing, the metallogenic pressure is from 100 to 170 MPa. Boiling caused by decreasing of fluid pressure is the most important reason of gold deposition.

Key words: Shuangwang gold deposit, oreforming fluid, fluid inclusion, fluid immiscibility