He–Ar Isotope Composition of Pyrite and Wolframite in the Tieshanlong Tungsten Deposit,Jiangxi, China: Implications for Fluid Evolution |
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Authors: | Guanglai LI Renmin HUA Wenlan ZHANG Dongquan HU Xinglin WEI Xiao'e HUANG Lei XIE Junming YAO Xudong WANG |
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Institution: | 1. State Key Laboratory for Mineral Deposit Research, Nanjing University, Nanjing, China;2. Jiangxi Bureau of Nonferrous Metal Exploration, Nanchang, China;3. Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China;4. East China Institute of Technology, Fuzhou, China |
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Abstract: | The Tieshanlong tungsten‐polymetallic deposit is a large wolframite deposit of quartz vein type located in southern Jiangxi, South China. It is genetically related to a high‐K S‐type granite. Seven pyrite and two wolframite samples, selected for He and Ar isotope analyses, yielded 3He/4He values of 0.04–0.98 Ra, 40Ar/36Ar ratios of 293.5–368.0, and 38Ar/36Ar ratios of 0.176–0.193. These data indicate that the ore‐forming fluids associated with the deposit did not result from a simple mixing of the crustal‐ and mantle‐derived end‐member fluids, but that primeval meteoric fluids were also involved in the generation of the associated granitic magma by partial melting of crustal metasedimentary rocks. Further investigations show that only minimal He from the mantle was added during generation of the associated granitic magma. It is postulated that boiling and second mixing with “new” meteoric fluids took place during migration of magmatic‐hydrothermal fluids into wall‐rock fractures, resulting in a drastic decrease of their metal transport capacity, which triggered the tungsten‐polymetallic mineralization. |
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Keywords: | China He– Ar isotope Jiangxi ore‐forming fluid quartz‐wolframite vein Tieshanlong tungsten deposit |
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