| 内蒙古白乃庙矿田十四万金矿床流体包裹体研究 |
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| 引用本文： | 钟日晨,李文博.内蒙古白乃庙矿田十四万金矿床流体包裹体研究[J].岩石学报,2009,25(11):2973-2982. |
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| 作者姓名： | 钟日晨 李文博 |
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| 作者单位： | 北京大学造山带与地壳演化教育部重点实验室,北京,100871 |
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| 基金项目： | 国家重点基础研究发展规划项目，国家自然科学基金项目 |
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| 摘 要： | 十四万金矿床是白乃庙矿田徐尼乌苏金矿化带内重要的石英脉型金矿,矿体产于EW向韧性剪切带的次级NE向断裂.成矿过程划分为3个阶段:早阶段形成无矿石英脉,石英遭受明显压应力作用,包裹体类型包括富水溶液型、富碳质型、纯碳质型,包裹体均一温度为260～420℃,平均盐度6.78%NaCl eqv;中阶段为硫化物-方解石-绿泥石-绢云母-细粒石英组合,充填早阶段石英的裂隙,未遭受明显应力作用,包裹体类型为富水溶液型和纯碳质型,包裹体均一温度为140～260℃,平均盐度7.22%NaCl eqv;晚阶段形成方解石脉,仅有富水溶液型包裹体,包裹体均一温度为140～180℃,平均盐度2.15%NaCl eqv.激光拉曼测试结果表明包裹体气相成份主要为CO_2、CH_4和少量N2.早阶段成矿流体为富碳质流体,成分为CH_4+CO_2+H_2O,中阶段流体为富水流体,成分为H_2O+CH_4,早、中阶段均发生了流体沸腾作用,早阶段强烈的沸腾作用使流体CO_2和CH_4含量降低,中阶段方解石沉淀使CO_2含量进一步降低,并导致了硫化物沉淀和金矿化.十四万金矿床流体包裹体特征、矿床地质特征均与造山型矿床一致,为造山型金矿,成矿流体可能源于徐尼乌苏组浅变质作用产生的变质流体,成矿构造背景可能为二叠纪末-三叠纪初华北板块与西伯利亚板块间的陆陆碰撞造山体制.
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| 关 键 词： | 内蒙古 十四万金矿床 流体包裹体 造山型金矿 大陆碰撞 |
Fluid inclusion study on the Shisiwan gold deposit in Bainaimiao ore field, Inner Mongolia, China |
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| ZHONG RiChen,LI WenBo.Fluid inclusion study on the Shisiwan gold deposit in Bainaimiao ore field, Inner Mongolia, China[J].Acta Petrologica Sinica,2009,25(11):2973-2982. |
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| Authors: | ZHONG RiChen LI WenBo |
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| Abstract: | The Shisiwan gold deposit is loacted in Xuniwusu gold mineralization belt in Bainaimiao ore field.The quartz veins are controlled by NE-trending faults which are the secondary structure of the EW-trending ductile-shear zone.The ore-forming process can be divided into three stages.The barren quartz veins were formed in early stage and then structurally deformed.The early stage fluid inclusion types are aqueous,carbonic-aqueous and carbonic.The homogenization temperature of early-stage fluid inclusions ranges 260 ～420℃,with average salinity of 6.78% NaCl eqv.The middle stage mineral paragenesis is sulfides+calcite+chlorite+sericite+fine-grained quartz,infilling fissions of early-stage quartz.The middle stage minerals do not show structurally deformation and contain aqueous and carbonic fluid inclusions.The homogenization temperature of middle-stage fluid inclusions ranges 140～260℃,with average salinity of 7.22% NaCl eqv.The late-stage calcite veins contain aqueous fluid inclusions yielding homogenization temperatures of 140～180℃,with average salinity of 2.15% NaC1 eqv.Laser Raman spectra indicates that gases in fluid inclusions are major of CO_2,CH_4and N_2.In general,the ore-forming fluid evolved from carbonic to aqueous,i.e.from CH_4+CO_2+H_2O,through to NaClH_2O+CH_4,and to NaCl-H_2O.Fluid immiscibility occurred in both early and middle stages and resulted in release of CO_2and CH_4.Calcite precipitation in middle stage reduced the activity of CO_2 and thus induced precipitation of sulfides and gold.Therefore,the study in both fluid inclusions and ore geology suggests that the Shisiwan deposit is a gold deposit of orogenic class.The ore-forming fluids are interpreted to have derived form metamorphic devolatilation of the Xuniwusu formation during late Permian-early Triassic collisional orogeny between the Siberia and North China continents. |
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| Keywords: | Inner Mongolia Shisiwan gold deposit Fuid inclusion Orogenic gold deposit Continental collision |
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