安徽滁州琅琊山矽卡岩型铜矿床成矿流体特征研究

The Characteristics Study on Ore-forming Fluid of Langyashan Skarn Type Copper Deposit in Chuzhou Area,Anhui Province

安徽滁州琅琊山铜矿床位于长江中下游成矿带滁县-庐江铜金成矿亚带,是该带最具典型且规模最大的矽卡岩型铜且伴生金矿床。对于成矿流体特征的研究,有助于深入探讨琅琊山铜矿床成矿作用过程及矿化富集机制。本文在详细的野外地质调查和岩矿鉴定的基础上,将该矿床的矿化阶段划分为矽卡岩阶段、退蚀变阶段、石英硫化物阶段和碳酸盐阶段,并开展了较为系统的流体包裹体研究工作。结果显示,该矿床原生流体包裹体类型有含子晶三相、气液两相、纯液相和纯气相包裹体;从矽卡岩阶段→退蚀变阶段→石英-硫化物阶段→碳酸盐阶段,热液流体温度由高温(372℃~486℃)至向低温(158℃~192℃)、盐度由中-高盐度(2.6~8.7wt% NaCleq)至低盐度(0.9~1.6wt% NaCleq)、成矿压力由高(61.3MPa)至低(29.4MPa)的趋势变化。表明琅琊山铜矿床的成矿流体初始表现为高温高盐度特征,随着成矿作用的进行,向低温低盐度流体演化。

The Langyashan copper-(gold)deposit is located in Chuxian-Lujiang copper-gold sub-belt of The Middle-Lower Yangtze River Metallogenic Belt,which is the most typical and has the largest scale.The study on the characteristics of ore-forming fluid is helpful to further discuss the metallogenic process and mineralization-enrichment mechanism.On the basis of detailed field geological survey and microscopic identification,we divided the mineralization stage into siliceous-skarn stage,retrograde alteration stage,quartz sulfide stage and carbonate stage,and carry out fluid inclusion research of Langyashan deposit.The result shows that the primary inclusions of the deposit include three phases containing daughter,gas-liquid two phases,pure liquid phase and pure gas phase inclusions.From siliceous-skarn stage,retrograde alteration stage,quartz sulfide stage to carbonate stage,the temperature of ore-forming fluid has evolved from high temperature(372℃~486℃)to low temperature(158℃~192℃),and the salinity evolved from medium-high salinity(2.6~8.7wt%NaCleq)to low salinity(0.9~1.6wt%NaCleq),and the ore-forming pressure changed from high(61.3MPa)to low(29.4MPa).It shows that the oreforming fluid of Langyashan skarn copper deposit is characterized by high temperature and salinity in the beginning,and with the development of mineralization,it evolves to low temperature and salinity fluid.