陕西神河钡矿床矿物流体包裹体特征与成矿物理化学条件 |
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引用本文:吴胜华,刘家军,柳振江,翟德高,邢永亮.2011.Fluid inclusion characteristics and metallogenic physicochemical conditions of Shenhe barium deposit, Shaanxi Province[J].Mineral Deposits,30(6):1100~1112 |
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基金项目:本文得到国家自然科学基金 (40573032、41173062)、高等学校学科创新引智计划(B07011)、长江学者和教育部创新团队发展计划等项目的资助 |
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中文摘要:陕西神河钡矿床位于南秦岭钡成矿带的北矿带,重晶石和毒重石为主要的矿石组成。显微测温分析表明,重晶石、毒重石和钡解石内流体包裹体的均一温度范围分别为108~205℃(峰值130~170℃)、118~274℃(峰值150~210℃)和146~227℃;盐度w(NaCleq)分别为0.53%~9.86%、0.18%~8.95%和4.03%~7.31%;激光拉曼分析表明,重晶石中流体包裹体气液相组成以H2O为主,毒重石中流体包裹体气相则含有CO2、N2、H2S和CH4,钡解石中流体包裹体气相也含有CO2和N2,石英中流体包裹体气相部分含有CO2、N2、H2S和CH4。以上研究成果反映了重晶石、毒重石和钡解石在成矿条件上的差异。毒重石的形成可能与热化学硫酸盐还原作用相联系,热化学硫酸盐还原作用消耗了热液流体中大量的有机气体和SO2-4;同时表明在形成毒重石期间,此反应抑制了重晶石的形成,热化学硫酸盐还原作用实现了碳从有机物来源(CH4等)到毒重石(碳酸盐)的转变过程。研究结果显示,流体温度较高、一定含量的CO2气体、较高Ba2+浓度、发生热化学硫酸盐还原作用前成矿流体中较高的HS-浓度和H2S较快速的扩散和转移的流体物理化学成矿环境是毒重石形成的重要条件。 |
中文关键词:地球化学 钡矿床 流体包裹体特征 成矿物理化学条件 神河 陕西 |
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Fluid inclusion characteristics and metallogenic physicochemical conditions of Shenhe barium deposit, Shaanxi Province |
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Abstract:The Shenhe barium deposit in Shaanxi Province occurs in the northern ore zone of the early Paleozoic South Qinling barium metallogenic belt Barite and witherite are main ore minerals. Microthermometric analyses show that the homogenization temperature ranges of the fluid inclusions in barite, witherite and barytocalcite are 108~205℃ (with main peak at 130~170℃), 118~274℃ (with main peak at 150~210℃) and 146~227℃, respectively, and the salinity ranges of the fluid inclusions in the barite, witherite and barytocalcite w(NaCleq) are 0.53%~9.86%, 0.18%~8.95% and 4.03%~7.31%, respectively. Laser Raman analyses show that the gas and liquid phase composition of the fluid inclusions in barite is H2O, the gas phase compositions of the fluid inclusions in witherite are composed of CO2, N2, H2S and CH4, the gas phase compositions of the fluid inclusions in barytocalcite include CO2 and N2 , and the gas phase compositions of the fluid inclusions in quartz consist of CO2, N2, H2S and CH4 It is concluded that metallogenic conditions of various kinds of barium minerals were different. The formation of witherite was possibly associated with thermochemical sulfate reduction, which consumed lots of organic gases and SO2-4 in hydrothermal fluids and also inhibited the formation of barite when witherite was formed. The authors thus hold that thermochemical sulfate reduction transferred carbon from organic gases into witherite. Relatively high fluid temperatures, the existence of CO2, fairly high Ba2+ concentrations, and the environment of high HS- concentrations and rapid diffusion of H2S in ore-forming fluids before thermochemical sulfate reduction constituted important factors for witherite formation. |
keywords:geochemistry, barium deposit, fluid inclusion characteristics, physicochemical conditions for mineralization, Shenhe, Shaanxi Province |
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