西藏甲玛铜多金属矿床围岩蚀变特征及成矿流体运移规律浅析

Wall rock alteration characteristics and migration regularity of mineralizing fluid of Jiama Cu polymetallic deposit in Tibet

甲玛铜多金属矿床围岩蚀变发育,可分为四期八个阶段,其中矽卡岩化、绢英岩化与成矿时空关系密切。通过对绢英岩化蚀变岩的质量平衡计算发现,导致绢英岩化围岩蚀变的热液为晚期岩浆分异的富挥发份的含矿硅质富钾酸性流体;并随着蚀变的发生发展,蚀变岩的主元素及成矿元素显示不同的迁移规律但表现出相似的蚀变流体运移趋势,即:以则古郎地区为中心,分别向铜山、铅山及莫古郎地区运移,由于铜山滑覆体阻挡,使得铜山地区蚀变较强,莫古郎地区较弱。

The development process of wall rock alteration in Jiama Cu polymetallic deposit can be divided into four phases or eight stages. During the process, the space and the time of mineralization is closely related to skarnization and sericitization. The calculation of mass balance of sericitized altered rock shows that the hy- drothermal fluid which caused the alteration of sericitized wall rock is a kind of volatile-rich mineral-laden si- liceous K-rich acidic fluid differentiated by late magma. During the process of alteration, the main elements and metallogenic elements of altered rock have different migration laws and similar migrating trend of altered fluids. The trend is that centering around Zegulang regions and migrating towards Tongshan, Qianshan and Mogulang regions. As the result of blocking of Tongshan slumped overthrust, the alteration in Tongshan re- gion is more intense than that in Mogulang region.