(1. 中南大學 有色金屬成礦預測與地質環(huán)境監(jiān)測教育部重點實驗室，長沙 410083； 2. 中南大學 地球科學與信息物理學院，長沙 410083； 3. 湖南華中礦業(yè)有限公司，長沙 410003)
摘 要: 李壩金礦床是禮岷金礦帶東段一個大型金礦床，礦體產于近NW向、EW向韌脆性剪切帶中。通過詳細的野外調研和室內鑒定，李壩成礦過程可以劃分為熱液期和表生期，其中熱液期可細分為黃鐵礦階段(A1)和黃鐵礦-絹云母-石英階段(A2)、多金屬硫化物階段(A3)等主成礦階段。包裹體巖相學分析和顯微測溫分析表明，A1階段流體包裹體以水溶液包裹體為主，還有少量的CO2包裹體(II型)、含CO2三相水溶液包裹體(III型)，均一溫度集中于380~400 ℃，鹽度集中于5%~8% NaCleq之間。A2階段流體包裹體以CO2包裹體(II型)、含CO2三相水溶液包裹體(III型)為主，水溶液包裹體較少，均一溫度集中于320~340 ℃之間，鹽度集中于8%~11% NaCleq之間。A3階段流體包裹體以CO2包裹體(II型)、含CO2三相水溶液包裹體(III型)為主，水溶液包裹體較少，均一溫度集中于280~300 ℃之間，鹽度集中于2%~6% NaCleq之間。通過H2O和CO2體系聯(lián)合p-t圖解估算成礦壓力為95~150 MPa，估算最大成礦深度為5.6 km。對比研究表明：李壩金礦床礦體呈似層狀、透鏡狀賦存于淺變質沉積巖中，且礦體與圍巖邊界模糊；金屬礦物主要為細粒黃鐵礦，上述礦床地質特征總體與卡林型金礦床一致，而流體包裹體特征指示該礦床成礦流體具有富CO2、中高溫、低鹽度的特征，這與造山型金礦床一致。綜合地質和流體包裹體特征，李壩金礦床成因類型為廣義的類卡林型。
關鍵字: 流體包裹體；成礦流體；類卡林型金礦；李壩金礦床；禮岷金礦帶
（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
