Fluid Geochemistry and Its Mineralization Significance of the Uranium Ore Deposit in Quanzhou,Guangxi Province

The uranium ore deposit located in Guangxi Quanzhou is of medium size,where the ore-bearing rocks are mainly in the strata of Devonian Sipai,Donggang Ling and Liu Jiang Groups.This deposit is controlled by the branching and secondary faults of the Xinning-Ziyuan-Lingchuan (Macheng-Guangji).fault zone Ancient granites provided a source of uranium.In the shallow environment,the carbonate complex [UO2(CO3)3]4-and [UO2(CO3)2]2-were decomposed to UO22+ (probably combined with F-to form UO2F42-),and finally these substances formed the uranium deposit.This work selects samples of granite and quartz in the Sipai Group which penetrates in granite to measure temperature of its quarts inclusions using the uniform and burst methods.Data analysis shows that the main types of fluid inclusions are gas-liquid inclusion,inclusion of sub-crystal,gas-rich inclusion and CO2 inclusion.Most of the inclusions are gas-liquid inclusions.According to the uniform method of measurement at the freezing temperature the data display high salinity and the average salinity of 10.3%.There are many inclusions of sub-crystal which display salinity of the over-saturated;the uniform temperatures are different,but the overall concentrates in 200 ℃～280 ℃.The average homogeneous temperature of the gas-liquid inclusions is 222 ℃.According to burst experiment,the measured temperature of burst is around 350 ℃.High temperature and high salinity indicate that ore-forming fluids are closely related with magmatic hydrothermal fluids.This work also selects the sample for carbon isotope test,and the result shows that the carbon was derived from magma carbon.Oxygen isotope test and hydrogen isotope test on the samples demonstrate that the fluid source is atmospheric precipitation,and also related with magmatic hydrothermal activity.Samples including wolframite and scheelite indicate the tungsten mineralization.Because of the U-W symbiotic,they further indicate uranium mineralization.Combined with the field observations and geochemical analysis of the sample data,this study suggests that mineralization of this ore deposit is closely related with rocks of the Yanshan period.