投稿时间：2024-08-12
修订日期：2025-03-11
网络发布日期：2025-04-25
中文摘要:矿床成因及成矿模式研究对于指导已知大型矿床深部找矿工作具有重要意义，白银厂铜多金属矿田作为中国最大且最为典型的海相火山岩赋矿块状硫化物（VHMS）矿集区，为北祁连铜多金属矿床的勘探和研究提供了重要依据。为了提高找矿精度、破解制约找矿突破的关键基础地质问题，文章系统地收集和整理了前人在矿田内开展的全岩微量元素、稀土元素、同位素地球化学以及矿石组构、流体包裹体、同位素年龄等数据，基于现代海底热液矿床研究的新认识，重新梳理了矿床成因和成矿模式。白银厂铜多金属矿田西、东部火山岩构造环境具有从岛弧裂谷向弧后盆地过渡的特点，矿石与酸性火山岩具有相同的成因和来源，推测由软流圈地幔发生部分重熔，且有部分地壳组分加入。成矿过程具有多期次的特点，与火山热液、岩浆热液具有密切的关系，局部则表现出沉积改造成因的特性。脉状矿体热液流体主要来自经历了去气作用的岩浆热液，而块状矿体热液流体主要是岩浆热液与海水的混合热液。奥陶纪岛弧裂谷（445~486 Ma）火山岩和中晚奥陶世（454~469 Ma）弧后盆地火山岩活动阶段是成矿的重要时期，据此，将白银厂矿田的成矿作用过程归结为3个阶段：① 中-晚寒武世成矿前阶段：低温热液携带S、Pb等部分成矿元素喷出海底为成矿作用奠定了物质基础；② 奥陶纪主成矿阶段：随着岩浆中水含量不断增加，富含挥发分（H2O、S、Cl等）且具有高氧逸度特征的玄武质成矿母岩浆与流体携带大量的金属成矿物质向上迁移，随着氧逸度、pH值、挥发分含量、温度、盐度及压力等物理化学条件的变化形成适合脉状、浸染状、块状矿体就位的物理化学障，造就了白银厂下部脉状矿体-中部浸染状矿体-上部块状矿体的特殊矿化空间结构；上地壳组分混入数量的多少及流体端员组分、成矿条件的差异可能是造成矿田东西部各矿床不同矿石组分特征的主要原因；③ 志留纪—泥盆纪成矿后阶段：褶皱变形、断裂以及区域性变质热液改造作用使矿体空间位置发生位移或破坏。文章为矿化空间结构特征研究和下一步找矿工作部署提供了科学的指导思路。
中文关键词:白银厂矿田 VHMS铜多金属矿床 矿床成因 成矿模式 综述
Abstract:The research on the genesis and metallogenic model of ore deposits is significant for guiding the ore prospecting in the deep edge of known large deposits. As the largest and most typical marine volcanic-hosted massive sulfide (VHMS) ore district in China, the Baiyinchang Cu polymetallic district provides an important basis for exploring and researching the Cu polymetallic deposits in North Qilian. To improve the precision of ore prospecting and solve the key basic geological problems that restrict the breakthrough of ore prospecting, combined with field investigation, this research systematically collected and sorted out the data of whole-rock trace, rare earth, isotopic geochemistry, ore fabric, fluid inclusions, isotopic age dating and other achievements carried out by predecessors in the ore field. The genesis and metallogenic model of the deposit have been reorganized on the basis of new insight on the modern sea floor hydrothermal deposits. As a typical concentrated area of VHMS-type copper-polymetallic deposits, the tectonic environment of volcanic rocks in the west and east of the Baiyinchang ore field has a transition from the island-arc rift environment to the back-arc basin environment. It is speculated that the ore and acid volcanic rocks have the same genesis and source, and it is assumed that partial remelting of the asthenosphere occurred and some crustal components were added. The ore-forming process has the feature of multistages and closely related with magmatic and volcanic hydrothermals, locally showing the characristics of sedimentary reworking. The hydrothermal fluid of vein-like ore body is mainly from the magmatic hydrothermal fluid that has undergone degassing, while the hydrothermal fluid of massive ore body is mainly magmatic hydrothermal fluid mixed with seawater; the forming stage of Ordovician continental margin island arc (445~486 Ma) volcanic rocks and the middle-late Ordovician (454~469 Ma) back-arc basin volcanic rocks are important periods of mineralization, thus the mineralization process can be summed up in three stages: ① The pre-mineralization stage in Middle-Late Cambrian period: low-temperature hydrothermal fluids carring some metallogenic elements such as S and Pb erupted at the seafloor, which laid the material foundation for mineralization; ② Ordovician main metallogenic stage: with the continuous increase of water content in the magma, the basaltic ore-forming parent magma and fluid are rich in volatiles (H2O, S, Cl, etc.) and characterized by high oxygen fugacity, which carry a large amount of metal ore-forming material and migrate upward, and with the changes of physical-chemical conditions such as oxygen fugacity, pH value, volatile content, temperature, salinity and pressure, a physical-chemical barrier suitable for the placement of vein-like, disseminated and massive ore bodies is formed, resulted in the formation of a special mineralization spatial structure: the vein-like ore body in the lower part, the disseminated ore body in the middle part, and the massive ore body in the upper part of the deposit; ③ The post-mineralization stage in Silurian-Devonian period: the fold deformation, fault and regional metamorphic hydrothermal reformation resulted in the displacement or destruction of the spatial position of the ore bodies. This paper may provide scientific guidance for the study of mineralization spatial structure characteristics and the deployment of next step prospecting program.
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基金项目:本文得到国家重点研发计划（编号：2022YFC2903305）、甘肃省自然资源科技创新与应用研究项目（编号：202406）、自然资源部黄河上游战略性矿产资源重点实验室开放课题资助项目（编号：YSMRKF202209）和甘肃省基础地质调查评价项目（编号：甘资勘函[2021]84、甘资勘函[2022]63号）联合资助
引用文本：
郭小刚,戴霜,韩峰,苟瑞,王秦,李正华.2025.甘肃白银厂铜多金属矿田矿床成因及成矿模式研究进展综述[J].矿床地质,44(2):432~456GUO XiaoGang,DAI Shuang,HAN Feng,GOU Rui,WANG Qin,LI ZhengHua.2025.Research progress on genesis and metallogenic model of Baiyinchang Cu polymetallic ore district in Gansu: A Review[J].Mineral Deposits44(2):432~456
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