李保华, 顾雪祥, 李黎, 徐仕海, 付绍洪, 陈翠华, 董树义. CO2-H2O流体不混溶对Au溶解度的影响——以贵州省贞丰县水银洞金矿床为例[J]. 地质通报, 2011, 30(5): 766-772.
    引用本文: 李保华, 顾雪祥, 李黎, 徐仕海, 付绍洪, 陈翠华, 董树义. CO2-H2O流体不混溶对Au溶解度的影响——以贵州省贞丰县水银洞金矿床为例[J]. 地质通报, 2011, 30(5): 766-772.
    LI Bao-hua, GU Xue-xiang, LI Li, XU Shi-hai, FU Shao-hong, CHEN Cui-hua, DONG Shu-yi. The effect of CO2-H2O fluid immiscibility on the solubility of Au: a case study of the Shuiyindong gold deposit, Zhenfeng County, Guizhou Province[J]. Geological Bulletin of China, 2011, 30(5): 766-772.
    Citation: LI Bao-hua, GU Xue-xiang, LI Li, XU Shi-hai, FU Shao-hong, CHEN Cui-hua, DONG Shu-yi. The effect of CO2-H2O fluid immiscibility on the solubility of Au: a case study of the Shuiyindong gold deposit, Zhenfeng County, Guizhou Province[J]. Geological Bulletin of China, 2011, 30(5): 766-772.

    CO2-H2O流体不混溶对Au溶解度的影响——以贵州省贞丰县水银洞金矿床为例

    The effect of CO2-H2O fluid immiscibility on the solubility of Au: a case study of the Shuiyindong gold deposit, Zhenfeng County, Guizhou Province

    • 摘要: 运用热力学原理和方法,研究了CO2-H2O流体不混溶作用对Au的溶解度的影响。结果表明,贵州水银洞金矿床的成矿流体是一种富含挥发分( fCO 2=70.79MPa)、酸性(pH=3.71)、还原性(fO 2=0.50×10-36MPa)、中温(267℃)、具有超压(180MPa)性质的含Au(a∑Au=3.744×10-8mol/L)流体。当超压流体的封闭层——炭质页岩因断裂作用而被破坏时,热液体系的压力发生骤降(28.50~35.30MPa),CO2-H2O流体发生不混溶作用,并有大量CO2溢出。CO2的流失可使成矿溶液的CO2逸度和O2逸度降低(fCO 2=0.80MPa、fO 2= 2.512×10-42MPa),酸碱度升高(pH=4.32),同时伴随温度的下降(224℃),成矿热液中Au溶解度的降低(a∑Au=3.790×10-9mol/L),从而快速沉淀下来成矿。

       

      Abstract: Based on the theory and method of thermodynamics,this paper discusses the effect of CO2-H2O fluid immiscibility on the solubility of Au. The results indicate that the ore-forming fluid in the Shuiyindong gold deposit was a kind of volatiles-rich( fCO 2=707.946bar),acid (pH=3.71),reducing (fO 2=5.012×10-36bar),mid-temperature (267℃) and overpressure (1800bar) gold-bearing fluid (a∑Au=3.744×10-8mol/L). When the closed layer of overpressure fluid was destroyed by the fault, pressure suddenly decreased (285~353bar), CO2-H2O fluid immiscibility occurred, and a large amount of CO2 overflowed. The fugacity of CO2 and O2 decreased (fCO 2=8.054bar,fO 2=2.512×10-41bar), pH increased (pH=4.32), and temperature decreased too (224℃) with the fluid immiscibility. This led to the solubility of Au in ore-forming hydrothermal solution(a∑Au=3.790×10-9mol/L), rapid precipitation of Au, and the formation of ore deposit.

       

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