陕西小秦岭金矿成矿流体特征及成矿过程研究

Study on the Ore-forming Fluid Characteristics and Process in Xiaoqinling Gold Deposit,Shaanxi Province

对陕西小秦岭地区金矿体分布特征、成矿阶段进行了系统研究,对主要金矿体进行了显微测温、激光拉曼光谱分析,并结合已有的研究成果,总结了小秦岭金矿成矿流体物化特征,分析了成矿模式。认为贯通全区的大月坪-金罗斑复式背形是陕西小秦岭主要控矿构造格架,复背形所派生次级脆韧性断裂控制矿体的展布,其中平行于褶皱枢纽近东西向断裂带是区域主要含矿构造;构造带产状陡变形成的虚脱部位是含金石英脉产出部位;成矿过程划分为4个阶段,主成矿期(Ⅲ、Ⅲ阶段)形成脉束状、网状、浸染状含金多金属硫化物矿;成矿流体为低盐度富CO2流体,发生于中温热液作用、中压环境;成矿流体的扩容减压和大气降水混染是矿质沉淀的原因之一。

This papers ystematically studied the distribution characteristics and ore-forming stages of gold orebody in Xiaoqinling area of Shaanxi Province through microthermometry and Laser Raman spertroscopy.The physicochemical characteristics and ore-forming model of Xiaoqinling gold deposit were analyzed.Based on the previous analysis,the authors hold that the compound antiform of Dayueping-Jinluoban is the main ore-controlling structural framework.The distribution of orebody is controlled by the secondary embrittlement ductile faults derived from the compound antiform.The main ore-bearing structure is along the east-west fault zoneparallel to the fold hinge.The ore-forming process is divided into four main stages.It is in the mineralization stage(phase Ⅲ) that formed gold-bearing polymetallic sulfide deposits.The ore-forming fluidis of low salinity and rich in CO2,with the metallogenic condition being medium temperature and medium pressure.The decrease of pressure by the expansion of mineralization space and the mixing of meteoric precipitation caused gold deposit precipitation.