地质通报2025，Vol.44Issue(4)：587-600,14.DOI:10.12097/gbc.2024.05.041
青海牛苦头铅锌矿床成矿岩体年龄与矽卡岩矿物学特征
Study on the age of ore-forming rock mass and mineralogical characteristics of skarn rocks in the Niukutou Pb-Zn deposit,Qinghai Province
摘要
Abstract
[Objective]The Qimantag metallogenic belt is an important porphyry-skarn polymetallic metallogenic belt in China,and the Niukutou deposit is a large-scale Pb-Zn polymetallic deposit discovered in this metallogenic belt in recent years.However,there is a lack of research on the relationship between the age of the ore-forming rock mass,skarn formation,and Pb-Zn mineralization.Additionally,the relationship between the physicochemical conditions for skarn formation and mineralization in this deposit has not been thoroughly explored,which restricts our understanding of the metallogeny.[Methoods]Through the zircon LA-ICP-MS dating and electron probe technology analysis methods,this paper provide detailed information on the mineralization age,skarn zoning,and mineral composition characteristics.[Results]The results indicate that the monzogranite closely related to skarn was formed at 389.9±2.2 Ma,indicating that the Niukutou mineralization occurred in the Middle Devonian.The skarn rocks of the Niukutou deposit exhibit obvious alteration zones,and overall belong to the calcium-magnesium series skarn rock formation.Near the ore-forming rock mass,there is a set of andradite and hedenbergite mineral assemblages,while far away from the ore-forming rock mass,there is a set of grossularite and Mn-hedenbergite mineral assemblages.The main skarn minerals in the retrograde metamorphic stage are ilvaite,tremolite,actinolite,etc.The MnO content is low near the ore-forming rock mass,and gradually increases away from the ore-forming rock mass.This suggests that the chemical composition of the skarn minerals in the retrograde metamorphic stage has a certain inheritance from the skarn minerals in the prograde metamorphic stage.The ore-forming hydrothermal fluid migrates from the proximal to distal end of the ore-forming rock mass(southwest to northeast),during which temperature,fO2,and pH gradually decrease.Mineralization changes from the high-temperature metal mineralization assemblage near the ore-forming rock mass to the Pb-Zn mineralization assemblage distal from the ore-forming rock mass.[Conclusions]Based on previous research,this article believes that the calcium-magnesium skarn formation related to Middle-Late Devonian magmatic rocks in the Qimantag may be a prospecting indicator for skarn Pb-Zn deposits in this region.The temperature,fO2,and pH gradually decrease during the migration of ore-forming hydrothermal fluids from the proximal to distal end(southwest to northeast)of the ore-forming rock mass.This change in physical and chemical conditions is the reason for the enrichment of manganese rich skarn minerals and Pb-Zn mineralization in the distal end of the ore-forming rock mass.关键词
铅锌成矿/中—晚泥盆世岩浆作用/钙-锰质矽卡岩建造/祁漫塔格Key words
Pb-Zn mineralization/Middle to Late Devonian magmatism/calcium-magnesium skarn formation/Qimantag分类
地质学引用本文复制引用
杨新雨,王新雨,王书来,王幻,吴锦荣..青海牛苦头铅锌矿床成矿岩体年龄与矽卡岩矿物学特征[J].地质通报,2025,44(4):587-600,14.基金项目
中国铜业重点科技项目《青海省格尔木牛苦头及外围铅锌成矿规律研究与潜力评价》(编号QHHX-KZ-JF2020-001) （编号QHHX-KZ-JF2020-001）
