摘要
斑岩钼矿与热液脉状铅锌银矿为两类重要的矿床类型,两者往往分别独立产出,但越来越来的勘查实例揭示二者也可共生产出,构成统一的成矿系统。斑岩钼-热液脉状铅锌银成矿系统,主要分布在北美西部、加拿大西南部、中国秦岭-大别地区、华北北缘及西拉沐伦带、大兴安岭北段-额尔古纳等地区。根据斑岩钼矿与热液脉状铅锌银矿的平面关系,成矿系统可分为近源和远源两类:近源时,两者直接叠置或者平面距离小于2km;而远源时,两类矿化平面距离一般不超过6km。成矿系统空间上表现可为上铅-锌-银、下钼的垂向叠置或者内钼、外铅-锌-银侧向共存的形式。时间上两类矿化一般近同期形成,或者相差通常不超过8Myr。成矿系统岩浆性质多为高演化的钙碱性花岗质岩浆,起源于下地壳且加入了不同比例的地幔物质。成矿系统的蚀变特征一般为斑岩钼矿化蚀变向热液脉状铅锌银矿蚀变的渐变,其中粘土化带与绢英岩化带是两类矿床的叠加区。钼矿化常与钾硅酸盐化或者绢英岩化带内侧密切相关,铅锌银矿化则常与浅部的低温硅化-绢云母-伊利石-水白云母化、碳酸盐化密切相关。基于S、Pb、Sr、Nd等同位素研究成果,钼铅锌银系统中成矿物质主要为岩浆来源,但可能有地层物质的加入。成矿流体主要以岩浆水来源为主,初始流体通常为单相中低密度流体,辉钼矿沉淀往往伴随着减压沸腾、大气水混合、冷却及/或水岩反应的进行,发生大规模钼矿化的温度区间通常在300~450℃。浅部脉状铅锌银矿化则由持续降温的流体在混入较多大气水或流体p H值中和而形成,温度区间在175~320℃。成矿系统空间上钼-铅-锌-银的分带,可能受控于流体演化过程中上述多个过程的综合叠加作用。通过总结对比钼铅锌银成矿系统、单一斑岩钼矿、单一热液脉状铅锌银矿床在勘查历史、
Porphyry molybdenum-vein-style lead-zinc-silver mineralization systems are principally distributed in the western part of North America,Qinling-Dabie orogen in China,northern margin of North China Craton,Xilamulun metallogenic belt,and Eerguna district-northern Great Xing’an Range.Based on the alignment relationships between porphyry Mo deposits and vein-style Pb-Zn-Ag deposits,this study divides this kind of mineralization system into proximal and distal types:the proximal type presents those include both types of deposits overlapped or aligned in the distance less than 2 km,and the distal type includes the alignment distance between two types of mineralization from 2 km to 6 km.In the cross-sections,vein-style mineralization can overlap in the upper part or distribute alongside porphyry-type mineralization.The deposit clusters were usually formed in the same period or may remain active for 8 Myr or shorter.The ore-forming magma of the system is tied to highly-evolved calc-alkaline granitic magmatism,and mainly derived from lower crust with different contribution of mantle material.The alteration patterns in the system are featured as the gradual evolution from the porphyry Mo-type to vein-style alteration,and among them,the argillic and phyllic alteration zones represent the transitional,overlapped district.Molybdenite mineralization is characteristic of potassic or inner phyllic zones,and galena+sphalerite+silver-host minerals assemblages often occur in the sericite+illite alteration and low-temperature carbonate alteration in the shallow part.Based on the S,Pb,Sr and Nd isotopic compositions,magma is considered as the predominant source for ore-forming material of the system,and strata may also make some contributions.Hydrothermal fluids causing Mo mineralization are exsolved from magma and showing characteristics of single-phase intermediate-density.This fluid undergoes various processes to precipitation molybdenum,such as decompression,phase separation,cooling,mixing and interaction with host rocks.The te
作者
金露英
秦克章
李光明
赵俊兴
李真真
JIN LuYing;QIN KeZhang;LI GuangMing;ZHAO JunXing;LI ZhenZhen(China Copper Corporation Limited,Beijing 100082,China;Key Laboratory of Mineral Resources,Institute of Geology and Geophysics,Chinese Academy of Sciences,Bijing 100029,China;Innovation Academy for Earth Science,Chinese Academy of Sciences,Beijing 100029,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Bijing 100049,China;Institute of Disaster Prevention,Sahe 065210,China)
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2020年第12期3813-3839,共27页
Acta Petrologica Sinica
基金
国家重点科技研发计划(2017YFC0601306)
国家自然科学基金项目(41872086、41762011)联合资助。
关键词
斑岩钼矿
脉状铅锌银矿床
成矿物质来源
流体演化
成矿系统
控制因素
勘查指示
Porphyry molybdenum deposit
Vein-style lead-zinc-silver deposit
Source of ore-forming materials
Fluid evolution
Mineralization systems
Controlling factors
Exploration implications
