内蒙古拜仁达坝银铅锌矿区成矿前围岩蚀变与元素迁移规律  

Pre-metallogenic wall-rock alterations and element migration features of Bairendaba Ag-Pb-Zn deposit,Inner Mongolia

作　　者：周增辉 杨振[2] 李晓峰 徐启东[2] ZHOU ZengHui;YANG Zhen;LI XiaoFeng;XU QiDong(Guangxi Transportation Science and Technology Group Co.,Ltd.,Nanning 530007,Guangxi,China;School of Earth Resources,China University of Geosciences(Wuhan),Wuhan 430074,Hubei,China;Hunan Center of Natural Resources Affairs,Changsha 410000,Hunan,China)

机构地区：[1]广西交科集团有限公司,广西南宁530007 [2]中国地质大学(武汉)资源学院,湖北武汉430074 [3]湖南省自然资源事务中心,湖南长沙410000

出　　处：《矿床地质》2023年第3期548-564,共17页Mineral Deposits

基　　金：中国地质调查局项目(编号:1202011085470)资助。

摘　　要：为了厘清内蒙古拜仁达坝银铅锌矿床围岩蚀变特征,探索蚀变流体-岩石相互作用过程中的元素迁移规律,在野外地质工作的基础上,文章开展蚀变岩岩相学研究,发现矿区内存在多期围岩蚀变,其中成矿前蚀变规模大、强度强、范围集中、类型丰富、多阶段叠加:从早阶段硅化-绢云母化、中间阶段黏土化-绿泥石化到晚阶段碳酸盐化,且蚀变程度逐步增强。文章对矿区内不同蚀变程度的石英闪长岩和黑云斜长片麻岩的主微量元素测试和质量平衡计算表明,随着蚀变过程中原生矿物减少、蚀变矿物增加,主微量元素发生规律性迁移。结合成矿作用以高中温硫化物充填为主,矿化脉穿切各类蚀变岩、成矿元素未随蚀变增强而富集等地质事实,文章认为该期蚀变与成矿并不是同一次流体-岩石相互作用的结果,该期蚀变的体积效应可能仅有利于后期成矿物质充填的构造-围岩条件的形成。This paper studies petrography of the altered wall rocks with different alteration intensities for clarifying the characteristics of wall-rock alterations and element migration features in fluid-rock interaction of the Bairendaba Ag-Pb-Zn deposit based on detailed field geological research.It shows that the types of alteration are multiplicate and the pre-metallogenic alteration which has large scale,concentrated scope and strong degree can be divided into three stages,namely early stage silicification-sericitization,middle stage argillation-chloritization,and late stage carbonatization with the intensity of alteration enhances by overprinting.The assay of major and trace elements and mass balance calculations of quartz diorite and biotite-plagioclase gneiss with different alteration intensities show that there is clear migration behavior of major and trace elements with decreasing of primary minerals and increasing of altered minerals.Combining the geological facts of the medium-high temperature sulfides filling,mineralization veins cutting through kinds of altered rocks,and the characteristics of ore-forming elements do not enrich with the enhancement of alteration obviously,it implies that the alteration fluids and mineralization fluids are not a result of the same fluid-rock interaction,and the alteration in wall rocks provides favorable condition of structure and wall rocks for filling of later ore bodies.

关 键 词：地质学 围岩蚀变 成矿前蚀变 质量平衡计算 元素迁移规律 拜仁达坝 

分 类 号：P618.52[天文地球—矿床学] P618.42[天文地球—地质学]