Fluid Inclusion Studies of Ore and Gangue Minerals from the Piaotang Tungsten Deposit, Southern Jiangxi Province, China |
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| Authors: | WANG Xudong NI Pei YUAN Shund LIU Jiqiang LI Mingyong LIU Hongxin |
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| Institution: | 1 Yuanpei College of Shaoxing University, Shaoxing, Zhejiang 312000, China
2 State Key Laboratory for Mineral Deposit Research, Institute of Geo-Fluids, School of Earth Science and Engineering, Nanjing University, Nanjing 210093, China;3 MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China;4 Key Laboratory of Submarine Geosciences, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou 310012, China |
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| Abstract: | The Piaotang deposit is one of the largest vein-type W-polymetallic deposits in southern Jiangxi Province, South China. The coexistence of wolframite and cassiterite is an important feature of the deposit. Based on detailed petrographic observations, microthermometry of fluid inclusions in wolframite, cassiterite and intergrown quartz was undertaken. The inclusions in wolframite were observed by infrared microscope, while those in cassiterite and quartz were observed in visible light. The fluid inclusions in wolframite can be divided into two types: aqueous inclusions with a large vapor-phase proportion and aqueous inclusions with a small vapor-phase ratio. The homogenization temperature (Th) of inclusions in wolframite with large vapor-phase ratios ranged from 280°C to 390°C, with salinity ranging from 3.1 to 7.2 wt% NaCl eq. In contrast, the Th values of inclusions with small vapor-phase ratios ranged from 216°C to 264°C, with salinity values ranging from 3.5 to 9.3 wt% NaCl eq. Th values of primary inclusions in cassiterite ranged from 316°C to 380°C, with salinity ranging from 5.4 to 9.3 wt% NaCl eq. Th values for primary fluid inclusions in quartz ranged from 162°C to 309°C, with salinity values ranging from 1.2 to 6.7 wt% NaCl eq. The results show that the formation conditions of wolframite, cassiterite and intergrown quartz are not uniform. The evolutionary processes of fluids related to these three kinds of minerals are also significantly different. Intergrown quartz cannot provide the depositional conditions of wolframite and cassiterite. The fluids related to tungsten mineralization for the NaCl-H2O system had a medium-to-high temperature and low salinity, while the fluids related to tin mineralization for the NaCl-H2O system had a high temperature and medium-to-low salinity. The results of this study suggest that fluid cooling is the main mechanism for the precipitation of tungsten and tin. |
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| Keywords: | fluid inclusion ore mineral gangue mineral infrared microscopic study quartz-vein-type-tungsten deposit Piaotang |
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