内蒙古翁牛特旗硐子铅锌矿床成矿流体性质与成因

摘要

硐子铅锌矿床发育在内蒙古西拉木伦河南侧、翁牛特旗少郎河铅锌多金属成矿带内.矿区出露的岩石主要为角闪石岩、花岗闪长岩等,矿体主要受断裂构造控制.矿化分为早期铜矿化和晚期铅锌矿化两个阶段.流体包裹体研究显示:硐子铅锌矿床主要发育气液两相包裹体,均一温度范围为120℃～180℃,盐度范围为0.4％ ～7.2％ NaCleqv,成矿压力范围为11.83 ～24.30 MPa,表明成矿流体具有中低温、低盐度的特点.碳-氧同位素分析结果显示成矿流体具有岩浆水与大气降水混合参与成矿作用的特点;硫同位素分析结果显示其成矿物质具有深源岩浆的特点.综合分析认为,在构造活动期,区域上活化的深源岩浆在上升过程中与下地壳及赋矿围岩发生部分熔融,并与下渗的大气降水发生混合,导致成矿流体在断裂构造有利的位置富集成矿.硐子铅锌矿为受断裂构造控制的中低温热液脉型矿床.%Dongzi Pb-Zn deposit is located at Shaolang River Pb-Zn polymetallic metallogenic belt of Wengniute Banner in the southern side of Xar Moron River in Inner Mongolia.Magmatic rocks exposed in study area are mainly hornblendite,granodiorite,etc.The orebodies are mainly controlled by fault structures.Mineralization process is divided into copper mineralization at early stage and lead-zinc mineralization at late stage.Fluid inclusion study shows that the deposit contains gas and liquid inclusions,with homogenization temperatures ranging from 120℃ to 180℃,salinities ranging from 0.4％ to 7.2％ NaCleqv and the pressures ranging from 11.83 MPa to 24.30 MPa,representing medium-low temperature and low salinity.Carbon-oxygen isotope analysis shows that the mixture of magrnatic water and meteoric water involved in the mineralization process.Sulfur isotope analysis results show that the ore-forming materials came from deep source magma.Comprehensive analysis indicates that during tectonic activity period,deep source magma moved up,causing partial melting of the lower crust and ore bearing rocks and mixed with the atmospheric precipitation,which led to the enrichment and mineralization of ore-forming fluid in favorable structural positions in the faults.In summary,Dongzi Pb-Zn deposit is low-temperature hydrothermal vein-type deposit which is controlled mainly by fault structures.