内蒙古扎兰屯地区铜山组变质作用与成矿分析

内蒙古扎兰屯地区铜山组根据变质作用类型可划分为区域变质岩、接触变质岩和气-液变质岩。原岩主体为砂泥质或火山复理石建造,以泥质沉积岩为主,在同沉积过程中伴有微弱的火山喷发,代表浅海相或向浅海相沉积过渡的类型,铜山组火山岩为大洋板块与大陆板块碰撞后形成的岛弧火山岩建造。野外地质调查确定铜山组地层历经两期变质作用,主期变质作用为华力西中期低绿片岩相变质作用,后期为燕山期普通角闪石角岩相变质作用,受接触-热液变质作用的改造,矽卡岩化和角岩化作用明显叠加,燕山晚期气-液变质作用是本区多金属、贵金属矿(床)化点成矿作用的主要因素。

Metamorphism and mineralization of Tongshan formation in Zhalantun area, Inner Mongolia

According to the types of metamorphism, Tongshan formation in Zhalantun area can be divided into regional metamorphic rocks, contact metamorphic rocks and gas-liquid metamorphic rocks. The protolith is mainly composed of sandy argillaceous flysch formation or volcanic flysch formation, mainly composed of argillaceous sedimentary rocks, accompanied by weak volcanic eruption in the process of synsedimentary, representing the type of sedimentary transition from shallow sea facies to shallow sea facies. The volcanic rocks of Tongshan formation are island arc volcanic rocks formed after the collision of oceanic plate and continental plate. Field geological survey shows that the Tongshan formation has experienced two stages of metamorphism. The main stage of metamorphism is the middle Variscan low greenschist facies metamorphism, and the later stage is the product of Yanshanian ordinary amphibole hornstone facies low-pressure metamorphic contact metamorphism. It has been reformed by contact hydrothermal metamorphism, and the skarnization and horni.cation are obviously superimposed. The gas-liquid metamorphism in the late Yanshanian is the main cause of the formation Main factors of polymetallic and precious metal mineralization.