滇西南翁孔坝铜多金属矿床绿泥石特征及其地质意义  

Characteristics and geological significance of chlorite in Wengkongba copper polymetallic deposit,southwestern Yunnan

作　　者：曾淑明 张艳[1,2] 韩润生[1,2] 刘飞[1,2] 王明志[1,2] 吴子卓 田映天 ZENG ShuMing;ZHANG Yan;HAN RunSheng;LIU Fei;WANG MingZhi;WU ZiZhuo;TIAN YingTian(Faculty of Land Resource Engineering,Kunming University of Science and Technology,Kunming 650093,Yunnan,China;Southwest of Geological Survey,Geological Survey Center for Non-ferrousMetals Resources,Kunming 650093,Yunnan,China)

机构地区：[1]昆明理工大学国土资源工程学院,云南昆明650093 [2]有色金属矿产地质调查中心西南地质调查所,云南昆明650093

出　　处：《矿床地质》2023年第4期828-844,共17页Mineral Deposits

基　　金：云南省万人计划“青年拔尖人才”(编号:YNWR-QNBJ-2019-157)、云岭学者(2014);云南省矿产资源预测与评价工程实验室(2012)云南省和昆明理工大学创新团队项目联合资助。

摘　　要：翁孔坝铜多金属矿床位于云县-景洪火山弧带北段,是该带典型的铜多金属矿床之一,具有良好的成矿条件和找矿潜力。绿泥石化是该矿床最重要的蚀变类型之一。文章在详细的野外工作基础上,通过对该矿床岩(矿)石样品的岩相学研究,利用电子探针和扫描电镜分析绿泥石的化学成分和形态特征,进而揭示绿泥石的形成环境,探讨绿泥石化与多金属矿化之间的关系。结果显示,该矿床中绿泥石主要有3种类型:包括沿裂隙和孔洞中充填的Chl-Ⅰ类绿泥石、铁镁质矿物蚀变形成且与斑铜矿-辉铜矿矿脉共生的Chl-Ⅱ1-2类绿泥石以及与方铅矿一起充填杏仁体的Chl-Ⅱ3类绿泥石。从Chl-Ⅰ类绿泥石→Chl-Ⅱ1-2类绿泥石→Chl-Ⅱ3类绿泥石,其氧逸度和硫逸度呈现出逐渐降低的演化规律,温度为188~297℃,反映出它们形成于中等硫逸度、低氧逸度、中低温的热液环境。该矿床绿泥石属于密绿泥石和铁斜绿泥石,其主要阳离子与Mg之间具有较强的相关性,为多期热液蚀变的产物,物质来源于矿区发育的一套中-基性火山岩,其形成机制为溶蚀-结晶和溶蚀-迁移-沉淀。绿泥石化的形成促进了铜、铅锌的活化和迁移,为热液中矿质沉淀提供了所需的氧化还原环境,可以作为矿床的找矿标志。The Wengkongba copper-polymetallic deposit is located in the northern part of the Yunxian-Jinghong volcanic arc belt,and is one of the typical copper-polymetallic deposits in the region,with good metallogenic conditions and prospecting potential.Chloritization is one of the most important alteration types of the deposit.On the basis of detailed field work,through the petrographic study of the rock(ore)samples of the deposit,the chemical composition and morphological characteristics of chlorite are analyzed by using electron microprobe and scanning electron microscope,and then the formation environment of chlorite is revealed,the relationship between chloritization and polymetallic mineralization is discussed.The results show that there are mainly three types of chlorite in the deposit,including Chl-Ⅰfilled in cracks and cavities,Chl-Ⅱ1-2 altered from ferromagnesian minerals and coexisting with bornite and chalcocite veins,and Chl-Ⅱ3 filled with galena in amygdala.From Chl-Ⅰ→Chl-Ⅱ1-2→Chl-Ⅱ3,the oxygen fugacity and sulfur fugacity of the chlorite show a gradual decreasing evolution rule,with the temperature of 188~297℃,reflecting that they were formed in a hydrothermal environment with medium sulfur fugacity,low oxygen fugacity and medium and low temperature.The chlorite of the deposit belongs to pycnochlorite and ferriclinochlorite,and its main cation has strong correlation with Mg,which is the product of multi-period hydrothermal alteration.The material comes from a set of intermediate-basic volcanic rocks developed in the mining area,and its formation mechanism is dissolution crystallization and dissolution migration deposition.The formation of chloritization promotes the activation and migration of copper,lead and zinc,and provides the necessary redox environment for the mineral precipitation in the hydrothermal solution,which can be used as a prospecting indicator of the deposit.

关 键 词：地球化学 绿泥石 电子探针 扫描电镜 找矿标志 翁孔坝铜多金属矿床 滇西南 

分 类 号：P575.1[天文地球—矿物学] P618.41[天文地球—地质学]