摘要
茂租铅锌矿床位于扬子地块西南缘茂租断裂和莲峰―巧家断裂交汇的三角带,是川滇黔铅锌多金属成矿域滇东北铅锌矿化集中区重要的铅锌矿床。根据矿床流体包裹体岩相观察发现,茂租铅锌矿床主成矿阶段包裹体类型简单,主要为富液相包裹体,气液比小,少量纯液相包裹体。显微测温工作表明主成矿阶段流体整体具有中高温(峰值235℃~250℃)、中低盐度(盐度10%~18%NaCleq v)、中低密度(密度ρ分布于0.75~0.85g/cm^3)特征,同时存在低盐度峰值(1%~6%)和高盐度峰值(20%~24%)两端元,可能是高低盐度流体混合的结果。群体包裹体成分分析表明各期流体成分相似,液相为Ca^(2+)-Na^+(Mg^(2+))-SO_4^(2-)-Cl^-(F^-)体系流体,气相主要为H_2O、CO_2,并含少量N_2及H_2、CO、CH_4等还原性气体。对以上流体包裹体成分数据分析发现,成矿流体主要源于盆地热卤水,有一部分的大气降水的参与,且在主成矿期为弱氧化性质流体(闪锌矿R<0.1),成矿晚期成矿流体具有较强还原性(晚期萤石R=0.997)。此外,碳氧同位素及流体包裹体氢氧同位素组成表明,成矿流体除盆地卤水和大气降水来源外,还存在变质水及少量有机质流体来源。
Maozu Pb-Zn deposit,located in the triangle intersection zone of Maozu fault and Lianfeng-Qiaojia fault at the southwest rim of Yangtze Block,is an important Pb-Zn deposit in northeast Yunnan Pb-Zn oreconcentrated area of Sichuan-Yunnan-Guizhou Pb-Zn polymetal metallogenic domain.According to the fluid inclusion petrography observation,it is shown that there are liquid-rich inclusions with low ratio of gas phase to fluid phase and a small amount of pure liquid inclusions in the main ore-forming stage of Maozu Pb-Zn deposit.Based on the results of microscopic temperature measurement,at the main stage of ore forming the fluid has middle-high temperatures（peak 235℃-250℃）,middle-low salinity（10%-18% NaCleqv）and middlelow density（0.75-0.85 g/cm^3）.The presence of low salinity peak（1%-6%）and high salinity peak（20%-24%）at the same time might be the mixture result of high and low salinity fluids.The composition analysis of group fluid inclusions has showed that the fluid compositions are similar in each stage,the liquid part of ore forming fluid is belonged to Ca^（2＋）-Na＋（Mg^（2＋））-SO_4^（2-）-Cl^-（F^-）system and the gas compositions of group fluid inclusions are mainly H_2O,CO_2 and a little N_2 and H_2,CO,CH_4.For the analysis of the data above,it is considered that the fluids are mainly derived from basin brine,and a part of meteoric water,with weak oxidized feature in the main mineralization（sphalerite R 0.1）.The late ore-forming fluids have strong reducibility（late fluorite R=0.997）.In addition,carbon and oxygen isotopic composition,and hydrogen and oxygen isotopic composition of fluid inclusions indicate that there are also metamorphic water and a small amount of organic matter fluid sources in addition to basin brine and atmospheric precipitation sources.
出处
《矿产与地质》
2017年第5期854-863,共10页
Mineral Resources and Geology
基金
中国地质调查局地质调查项目(编号:12120114019701)资助
关键词
茂租铅锌矿
地球化学
成矿流体
包裹体
同位素
云南
Maozu Pb-Zn deposit, geochemistry, ore-forming fluid , fluid inclusion, isotope, Yunnan
