(1. 中南大学 有色金属成矿预测与地质环境监测教育部重点实验室，长沙 410083； 2. 中南大学 地球科学与信息物理学院，长沙 410083； 3. 湖南华中矿业有限公司，长沙 410003)
摘 要: 李坝金矿床是礼岷金矿带东段一个大型金矿床，矿体产于近NW向、EW向韧脆性剪切带中。通过详细的野外调研和室内鉴定，李坝成矿过程可以划分为热液期和表生期，其中热液期可细分为黄铁矿阶段(A1)和黄铁矿-绢云母-石英阶段(A2)、多金属硫化物阶段(A3)等主成矿阶段。包裹体岩相学分析和显微测温分析表明，A1阶段流体包裹体以水溶液包裹体为主，还有少量的CO2包裹体(II型)、含CO2三相水溶液包裹体(III型)，均一温度集中于380~400 ℃，盐度集中于5%~8% NaCleq之间。A2阶段流体包裹体以CO2包裹体(II型)、含CO2三相水溶液包裹体(III型)为主，水溶液包裹体较少，均一温度集中于320~340 ℃之间，盐度集中于8%~11% NaCleq之间。A3阶段流体包裹体以CO2包裹体(II型)、含CO2三相水溶液包裹体(III型)为主，水溶液包裹体较少，均一温度集中于280~300 ℃之间，盐度集中于2%~6% NaCleq之间。通过H2O和CO2体系联合p-t图解估算成矿压力为95~150 MPa，估算最大成矿深度为5.6 km。对比研究表明：李坝金矿床矿体呈似层状、透镜状赋存于浅变质沉积岩中，且矿体与围岩边界模糊；金属矿物主要为细粒黄铁矿，上述矿床地质特征总体与卡林型金矿床一致，而流体包裹体特征指示该矿床成矿流体具有富CO2、中高温、低盐度的特征，这与造山型金矿床一致。综合地质和流体包裹体特征，李坝金矿床成因类型为广义的类卡林型。
关键字: 流体包裹体；成矿流体；类卡林型金矿；李坝金矿床；礼岷金矿带
（1. Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring, Ministry of Education, Central South University, Changsha 410083, China; 2. School of Geosciences and Info-Physics, Central South University, Changsha 410083, China; 3. Hunan Huazhong Mining Co., Ltd, Changsha 410083, China）
Abstract:Liba gold deposit is a large deposit, which is located in the east area of Lixian-Minxian metallogenic belt and ore bodies of which are hosted in NW, EW directional dutile-brittle shear zones. Based on detailed field investigation and indoor identification, mineralization in Liba gold deposit can be divided into hydrothermal period and exogenous period. The hydrothermal stage can be subdivided into pyrite stage(A1) and main stages of mineralization including pyrite-sericite-quart stage(A2) and polymetallic stage(A3). A comprehensive study, including petrography and microthermometry shows that A1 stage fluid inclusions are dominated by H2O-solution and minor of CO2-bearing, pure CO2 in compositions, with homogenization temperature clustering concentrated in the range from 380 ℃ to 400 ℃, and the salinities concentrated in the range from 5% to 8% NaCleq. The A2 stage fluid inclusions are dominated by pure CO2, CO2-bearing and minor H2O-solution in composition, with homogenization temperature clustering concentrated in the range from 320 ℃ to 340 ℃, and the salinities concentrated in the range from 8% to 11% NaCleq. The A3 stage fluid inclusions are dominated by pure CO2, CO2-bearing and minor H2O-solution in composition, with homogenization temperature clustering concentrated in the range from 280 ℃ to 300 ℃, and the salinities concentrated in the range from 2% to 6% NaCleq. The fluid inclusions are deduced to be trapped at pressure of the range from 95 MPa to 150 MPa, with the largest metallogenic depth is estimated 5.6 km. Comparative analysis shows that Liba gold deposit accord with carlin type gold deposit in stratoid and lenticular orebody hosted in low metamorphic sedimentary rock, fuzzy boundary between orebody and surrounding rock and fine pyrites, while it accord with orogenic gold deposit, because the fluid inclusion analysis shows that the mineralization fluid is characteristic by CO2-bearing, medium-high temperature and low salinity. Based on geological and fluid inclusions characteristics, Liba gold deposit is regarded as carlin-like gold deposit.
Key words: fluid inclusion; ore-forming fluid; carlin-like gold deposit; Liba gold deposit; Lixian-Minxian metallogenic belt
