| 海南抱板金矿田流体包裹体地球化学研究 |
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| 引用本文：.1994.Fluid inclusion geochemical study on the Baoban gold field, Hainan Island, South China[J].Mineral Deposits,13(2):172~180 |
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| 中文摘要:对海南抱板金矿田的土外山、抱板和二甲等三个金矿进行的流体包裹体研究表明成矿流体为低盐度（0.1～6wt％NaCl)、中低温(200～240℃)热液，处于中低压力(60～160 MPa)下，其CO2含量较低。探针质谱分析表明流体包裹体中存在H2S，结合SO42-的存在，金在热液中可能是以硫氢络合物的形式迁移的。 |
| 中文关键词:流体包裹体 金矿田 海南抱板 |
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| Fluid inclusion geochemical study on the Baoban gold field, Hainan Island, South China |
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| Abstract:The Baoban gold field, located in Hainan Island, South China, consists of three gold deposits, namely, Tuwaishan, Baoban, and Erjia. These three gold deposits are very similar in geological characteristics and all belong to wall-rock alteration type. Three mineralization stages can be recognized: (1) quartz-pyrite-arsenopyrite stage; (2) polymetallie sulfide-gold stage; (3) quartz-calcite stage. Fluid inclusions can be divided into three composition types by their appearance and their cooling and heating behavior: (1) aqueous fluid inclusions; (2) H2O-CO2 fluid inclusions and (3) single-phase fluid inclusions. The microthermometric experiments were undertaken on an improved fluid inclusion stage of the U.S. Geological Survey. The salinity of the fluid is about 0.2％～6％ NaCl wt eq. The homogenization temperature is about 200 to 240℃, but varies with mineralization stages: 160～170℃ at StageⅠ,200～2400℃ at StageⅡ, and 150℃ at Stage Ⅲ. The pressure of the ore-forming fluid is about 60～160 MPa. The main gas components of the fluid inclusions are CO2，H2O，CO，CH4 and H2S as determined by solid-probe mass spectrometric analysis. A comparison with other gold deposits shows that there may exist relations between gold deposit types and content of gaseous H2S. The content of gaseous H2S in gold deposits of the gold-quartz vein type is lower than that in the wall-rock alteration type. Using the equation CH4+2O2=CO2+2 H2O and the gas composition. it is estimated that the oxygen fugacity is about 10-40．Chromatographic analysis shows that the major anions in the fluid inclusions are F-, Cl-, SO42-, while the major cations are Na+, K+, Ca2+, Mg2+. When chemical equilibrium is considered，the coexistence of H2S in gaseous phrase and SO42- in liquid phase and the reduction environment of the fluid(fO2=10-40) imply that there exists HS- in the fluid, and that gold in this fluid can easily form Au(HS)2- and might be transported as Au(HS)2- .It can be therefore concluded that the ore-forming fluid in this gold field is a low-medium salinity (0.2～6 NaCl wt％eq. ), low-medium temperature(200～240℃) hydrothermal fluid with low-medium pressure(60～160 MPa)，with gold probably transported in the form of AU(HS)2-. |
| keywords:Fluid inclusion, geochemistry, gold field, Hainan Island |
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