安徽定远小庙山金矿床流体包裹体研究  

A study of fluid inclusions of the Xiaomiaoshan gold deposit in Dingyuan County,Anhui Province

作　　者：张军[1] 杨劼[1] 徐兆文[1] 毛鸿丽[1] 

机构地区：[1]内生金属矿床成矿机制研究国家重点实验室南京大学地球科学与工程学院,江苏南京210093

出　　处：《岩石矿物学杂志》2010年第5期551-561,共11页Acta Petrologica et Mineralogica

基　　金：地质矿产部95攻关项目(9501102-04-1);国家自然科学基金资助项目(40973030)

摘　　要：小庙山金矿床原生流体包裹体分为4种类型:富气相的两相水溶液包裹体、富液相的两相水溶液包裹体、含CO2三相水溶液包裹体和含子矿物的三相水溶液包裹体,均一温度变化于133～378℃之间,峰值区间分别为180～200℃和220～260℃;盐度介于0.2%～44.6%之间,峰值区间为3%～6%。激光拉曼分析显示,流体包裹体的气相成分主要为CO2、H2O及少量CH4;包裹体群分析显示,成矿流体气相成分主要为CO2、N2、H2O、CH4、C2H2和C2H6,液相成分主要为Na+、K+、Ca2+、F-、Cl-、NO3-和SO42-,其中K+/Na+为1.55～2.75,F-/Cl-为0.02～0.03。矿化石英脉中,流体的δ18OH2O值介于-2.39‰～2.14‰之间,δDH2O值介于-51.2‰～-45.9‰之间,表明成矿流体主要来自岩浆,后期混入大气降水。依据成矿地质背景和矿区内成矿流体的地球化学及同位素资料,认为近南北向断裂是成矿流体运移通道和金富集沉淀的场所。在断裂破碎带中,高温高盐度成矿流体与大气降水混合,引起成矿流体的温度和盐度降低,压力变小,使得流体中的金沉淀成矿。The Xiaomiaoshan gold deposit in Dingyuan County of Anhui Province is a typical quartz vein type gold deposit in the central southern part of Zhangbaling uplift adjacent to the Tan-Lu fault belt in the west.Gold mineralization mainly occurs in NNE-extending quartz veins in the peripheral contact zone of Guandian-Wawuliu adamellite and subordinately exists as sparse disseminations in altered rocks.Petrographic studies reveal four types of primary fluid inclusions in quartz veins sampled from the Xiaomiaoshan gold deposit,i.e.,vapor-rich,liquid-rich,CO2-bearing and daughter minerals-bearing fluid inclusions.Fluid and stable isotopic geochemical methods,such as microthermometry,laser Raman microprobe,bulk composition and H-O isotopic analysis of fluid inclusions,were used to investigate physicochemical properties,chemical composition and sources of the ore-forming fluids so as to probe into the metallogenic mechanism of this type of ore deposits.The homogenization temperatures of these fluid inclusions range from 133℃ to 378℃,with the peak values being in the ranges of 180℃～200℃ and 220℃～260℃.The calculated salinities[w（NaCl）] range from 0.2% to 44.6%.with the peak values between 3% and 6%.Four types of fluid inclusions coexist in the sample;the vapor-rich fluid was homogenized to a single vapor phase,while at the similar temperature range,the liquid-rich fluid was homogenized to a single liquid phase.These phenomena indicate that the boiling process might have played an important role at the ore-forming stage.According to homogenization temperatures,salinities and vapor-liquid ratios,the fluid pressures were estimated to be 4 to 13 GPa,23 and 60 GPa,respectively,suggesting that gold mineralization took place over 6.5 km in depth.Based on the laser Raman analysis of the fluid inclusions,it is found that the gas composition is mainly CO2,H2O vapor with a tiny amount of CH4.Group analyses of fluid inclusions indicate that the liquid phase mainly contains Na＋,K＋,Ca2＋,F-,Cl-,NO-3 and SO2-4,whil

关 键 词：物理化学条件 成矿物质 流体包裹体 激光拉曼 氢氧同位素 小庙山金矿床 安徽定远 

分 类 号：P597[天文地球—地球化学]