地质与勘探2012，Vol.48Issue(4)：663-676,14.
内蒙古西拉木伦成矿带劳家沟斑岩型钼矿流体包裹体特征及地质意义
Characteristics of Fluid Inclusions from the Laojiagou Porphyry Mo Deposit in the Xilamulun Metallogenic Belt,Inner Mongolia and Their Geological Significance
摘要
Abstract
The Laojiagou deposit,which has been recently found at Tianshan town,Ar Horqin Banner,east of the Xilamulun metallogenic belt,is a porphyry Mo deposit.It is hosted in the fine-grained porphiric monzogranite,dominated by veinlet-disseminated molybdenite mineralization.There were three stages involved in the ore-forming process：early stage（quartz-molybdenite-pyrite assemblage）,middle stage（quartz-polymetallic sulfide assemblage） and late stage（quartz-calcite assemblage）.The early stage-related quartz veins contain abundant fluid inclusions（FI）,including pure gas FI,pure liquid FI,CO2-bearing three-phase FI,liquid-rich FI,gas-rich FI and daughter mineral-bearing multiphase FI,in which halite,anhydrite and other unknown minerals are contained.Compared with the early stage,the middle stage lacks of C-type FI.The number and diversity of the late stage fluid inclusions decreases dramatically,with a small amount of L-type and V-type FI.Petrography,microthermometry and laser Raman analysis on FI indicate the ore-bearing fluid is magmatic hydrothermal fluid characterized by high-temperature,hypersaline,high-oxygen and CO2-bearing.From the early stage to late stage,it evolved regularly from high-temperature（320~〉550℃）,hypersaline（6~16wt%NaCleqv,52.89~〉66.75wt%NaCleqv）,high-oxygen fugacity and CO2-rich,then high-medium-temperature（280~〉550℃）,hypersaline（5~15wt%NaCleqv,〉66.75wt%NaCleqv）,CO2-bearing,to medium-low temperature（160~250℃）,low salinity（0.5~5wt%NaCleqv） and CO2-barren.Based on the relationship among the liquid-vapor homogenization（ThL-V）,halite dissolution temperature（Tmhalite） and pressure,the minimum trapped pressure has been estimated,which suggests that the mineralization depth is approximately 5~7km.The ore-forming mechanism of the Laojiagou porphyry Mo deposit is inferred as follows：immiscibility occurred in the process of magmatic intrusion,causing the escape of ore-bearing hydrothermal fluid from magma.Then,boiling extensively took place during the period of the crustal uplifting,resulting in the precipitation of metal in the hydrothermal fluid.According to regional metallogenic regularity,the mineralization age of the Laojiagou porphyry Mo deposit is most likely to be the early Cretaceous,when the lithospheric of Eastern China was greatly thinning.关键词
斑岩钼矿/流体包裹体/劳家沟/西拉木伦成矿带Key words
porphyry Mo deposit/fluid inclusion/Laojiagou/Xilamulun metallogenic belt分类
天文与地球科学引用本文复制引用
刘利,曾庆栋,刘建明,段晓侠,孙守恪,张连昌..内蒙古西拉木伦成矿带劳家沟斑岩型钼矿流体包裹体特征及地质意义[J].地质与勘探,2012,48(4):663-676,14.基金项目
国家自然科学基金项目 （）
