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| A Study on Fluid Inclusions of the Keyue Pb-Zn-Sb-Ag Deposit in Southern Tibet, China |
| DU Xiao-fei1,2, CHENG Wen-bin2, LI Bao-hua2, LI Guan-qing3 |
1. The National 305 Project Office of Xinjiang, Urumqi 830000, China;
2. College of Earth Sciences, Chengdu University of Technology, Chengdu 610059, China;
3. Regional Geological Survey Party of Tibet Bureau of Geology and Exploration, Lhasa 851400, China |
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Abstract In order to investigate characteristics of ore-forming fluid and the ore-forming mechanism of the Keyue Pb-Zn-Sb-Ag deposit in the Southern Tibet Sb-Au metallogenic belt, fluid inclusions in three stage ore-bearing quartz, siderite/rhodochrosite and calcite veins from the Keyue Pb-Zn-Sb-Ag deposit have been studied through the petrography, microthermometry and the Laser Raman spectrometry. Results show that homogenization temperatures, salinities and densities are 250-281℃, 10.24%-15.17% NaCleqv,and 0.9-0.95 g/cm3 for fluid inclusions in stage Ⅰ minerals, 173-330℃, 3.87%-33.19% NaCleqv,and 0.85-1.00 g/cm3 for fluid inclusions in stage Ⅱ minerals, and 173-241℃, 3.06%-12.62% NaCleqv,and 0.85-1.15 g/cm3 for inclusions in stage Ⅲ minerals, respectively. From stage I to stage Ⅲ, ore-forming fluids are changed from a CO2-bearing H2O-NaCl system with moderate homogenization temperature and moderate salinity, to a CO2-H2O-NaCl system with moderate homogenization temperature, high to low salinities, and enriched metal elements, and to an aqueous fluid with medium to low temperatures and low salinity. On the basis of characteristics of fluid inclusion assemblages and microthermometric results, it is believed that the ore-forming fluid has experienced the un-mixing process which is the main factor caused the precipitation of large quantity hydrothermal minerals in the deposit.
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Received: 05 December 2014
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