论梅仙块状硫化物矿床的特征及成矿地质环境

GEOLOGICAL CHARACTERISTICS AND FORMATION ENVIRONMENT OF THE MEIXIAN MASSIVE SULFIDE DEPOSIT

梅仙铅锌矿床产于双峰式火山岩系内，火山岩的岩石化学、稀土和微量元素特征的研究表明其形成于大陆裂谷环境中，闽中裂谷带的发生、发展和演化控制着梅仙矿床的成矿过程。梅仙铅锌矿床特征的研究揭示其是与裂谷火山活动有关的块状硫化物矿床，并经后期热液叠加改造。梅仙矿床的成矿金属成分、地质环境、火山活动特征以及地壳拉张程度均表明梅仙矿床是介于华南型和Ｂｅｓｓｈｉ型间的过渡类型。

The Meixian lead zinc deposit in Fujian Province occurs in a bimodal volcanic sequence.Petrochemical and geochemical studies indicate that this volcanic sequence was formed in a Late Proterozoic continental rift,namely the Minzhong rift.The rift began to form on the crystalline basement composed of gneiss of the Middle Proterozoic Dikou Group and was closed during Caledonian collision which was accompanied by greenschist facies metamorphism,migmatization,granitization,overthrusting and ductile shearing. Host rock lithology,orebody shapes,ore mineral assemblages,ore textures and structures,isotope compositions and fluid inclusion features illustrate that Meixian is a massive sulfide deposit formed by submarine exhalation and was subjected to late transformation and superimposition.Based on comparison with other deposits in such aspects as ore metals,tectonic settings,lithologies and amounts of accompanying volcanic activites,it is considered that the Meixian deposit is a transitional deposit between the South China type and the Besshi type massive sulfide deposits.