(1. 中南大学有色金属成矿预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)
摘 要: 老鸦岭铜矿床是安徽省铜陵冬瓜山矿田内的一个矽卡岩型矿床。矿体赋存于远离主接触带的下二叠统到下三叠统大理岩地层中。原生成矿过程分为矽卡岩期的早矽卡岩阶段(A1)、晚矽卡岩阶段(A2)、氧化物阶段(A3)和热液期的石英硫化物阶段(B1)、碳酸盐阶段(B2)。包裹体岩相学分析表明：石榴子石、透辉石、石英和方解石中发育着气液两相包裹体(Ⅰ型)和含子矿物包裹体(Ⅱ型)。显微测温结果显示：早矽卡岩阶段，包裹体均一温度为434~579 ℃或者＞600℃，盐度连续分布在20.80%~56.70%，显示其成矿流体具有高温、高盐度的特征，体系处于超高压环境；氧化物阶段，流体减压沸腾，最低沸腾温度为298℃，包裹体具有不均一捕获特征，地下水的混入导致盐度从59.36%到3.76%显著变化，由于处于开放体系，受静水压力影响，估算成矿压力范围为16~37 MPa，结合上覆地层的厚度判断成矿深度约为1.6 km；石英硫化物阶段，包裹体均一温度集中于250~350℃，盐度在3.92%到49.22%之间；碳酸盐阶段，包裹体均一温度为160~193℃，盐度为2.63%~4.39%，成矿流体显示出从高温到低温、从高盐度到低盐度、从均一到不混溶分离的演化过程。基于以上研究，推断老鸦岭铜矿床的成矿流体以高温、高盐度的岩浆流体为开端，在上侵和沿大隆组地层快速运移过程中逐渐演化，伴随沸腾作用和两次地下水的混入，成矿流体温度、盐度、压力不断下降，最终在青山脚背斜轴部卸载成矿。
关键字: 流体包裹体；成矿流体；铜矿床；成矿作用；矽卡岩
（1. Key Laboratory of Metallogenic Prediction of Nonferrous Metals, Ministry of Education,
Central South University, Changsha 410083, China;
2. School of Geosciences and Info-Physics, Central South University, Changsha 410083, China）
Abstract:TheLaoyaling copper deposit, located at the Dongguashan mining area, Tongling, Anhui Province, China, is a skarn deposit. The orebodies are mainly located in the marble of the Lower Permain to the Lower Triassic strata, which is far from the contact zone. The primary ore-forming process is divided into skarn period and hydrothermal period. The former period can be subdivided into early skarn stage(A1), late skarn stage(A2) and oxide stage(A3), and the latter period can be subdivided into quartz sulfide stage(B1) and carbonate stage(B2). The characteristic of ore-forming fluids and mineralization were discussed by petrographical and microthermometric data of the fluid inclusion. Two types of inclusions, gas-liquid two-phase aqueous inclusions(type Ⅰ) and aqueous inclusions with daughter mineral(type Ⅱ), are hosted in garnet, diopside, quartz and calcite. The inclusions of early skarn period homogenize at temperatures of 434-579 ℃ or ＞600℃and have salinities of 20.80%-56.70%, indicating that the ore-forming fluids in this stage have the characteristics of high temperature, high salinity, and ultrahigh pressure. The oxide period, owing to the decrease of pressure, ore-forming fluids started to boil at the lowest temperature of 298℃, which shows the characteristics of heterogeneous capture of inclusions, and changes the salinity from 59.36% to 3.76% obviously by inburst of groudwater. The system is affected by the hydrostatic pressure in the open system with metallogenic pressure changing from 16 MPa to 37 MPa, together with thickness of the overly strata, the metallogenic depth is deduced to be 1.6km. The inclusions of quartz-sulfide period homogenizing at temperature of 250-350℃ have salinities of 3.92%-49.22%, and in carbonateperiod homogenizing at temperatures of 160-193℃, the inclusions have salinities of 2.64%-4.39%. The results demonstrates that the ore-forming fluids evolve from high-temperature to low-temperature, from high-salinity to low-salinity and from homogenization to immiscible separation. The ore-forming fluid is originated from different evolutional stages of the primitive fluids derived from the magmatic intrusion, and started with characteristics of high temperature and high salinity. The ore-forming components were precipitated in Qingshanjiao anticline due to twice boiling and fluid mixing as well as the decrease in salinity, temperature and pressure of the fluids.
Key words: fluid inclusion; ore-forming fluid; copper deposit; metallogenesis; skarn
