冈底斯北缘沙让斑岩钼矿蚀变矿化特征及与典型斑岩钼矿床的对比  

Characteristics of Alteration and Mineralization in the Sharang Pophyry Molybdenum Deposit in the Northern Margin of Gangdese and Comparison with Typical Porphyry Molybdenum Deposits in the World

作　　者：赵俊兴[1,2] 秦克章[1] 李光明[1] 李金祥[1] 

机构地区：[1]中国科学院矿产资源研究重点研究室,中国科学院地质与地球物理研究所,北京100029 [2]中国科学院研究生院,北京100049

出　　处：《地质与勘探》2011年第1期54-70,共17页Geology and Exploration

基　　金：全国危机矿山替代资源找矿综合研究项目(编号:20089932);国家自然科学基金(编号:40772066);国家“十一五”科技支撑计划项目(编号:2006BA01A04)联合资助成果

摘　　要：西藏沙让大型斑岩型钼矿床系冈底斯多金属成矿带首例斑岩型钼矿床,产于印亚大陆碰撞带的主碰撞期。本文分析了其蚀变和矿化特征,指出沙让钼矿床蚀变类型包括钾硅酸盐化(包括钾长石化和黑云母化)、绿帘石-绿泥石化、硅化、绢英岩化(石英-绢云母-黄铁矿化)和粘土化(高岭土化和伊利石-水白云母化)。矿化类型主要以脉状矿化、网脉状矿化和纹层状石英-辉钼矿脉为主,少量为浸染状矿化、星点状矿化(分布在角砾岩的基质中)和微细辉钼矿脉状矿化。该矿地表以粘土化和绢英岩化为主,剥蚀程度甚低,深部找矿潜力巨大。作者还选取世界部分典型斑岩型钼矿床进行蚀变和矿化特征的系统对比,指出斑岩型钼矿床有其自身独特的蚀变分带和矿化特征,其中钾化和绢英岩化是与矿化最为紧密的蚀变,而斑岩型钼矿具备特征的富氟的矿物蚀变带(如黄玉带或含萤石的蚀变带)。而矿体的产出一般呈矿化壳的形式在成矿岩体上部呈披覆状水平产出,常见有多层矿体。多种矿化特征中以网脉状矿化和纹层状石英-辉钼矿脉最为特征,常见有脉状蚀变和角砾岩化矿化。最后讨论了本项研究对于冈底斯多金属成矿带的勘查工作和研究的意义,以及与印亚大陆碰撞带东侧斑岩钼矿产出联系的可能性。The large-scale Sharang porphyry molybdenum deposit,as the firstly discovered single molybdenum porphyry-type deposit in the Gangdese metallogenic belt,formed in the main-stage of India-Asia continental collision with distinct characteristics of alteration and mineralization.The alteration types include potassic-silicate alteration（K-feldspathization and biotitization）,chlorite-epidote alteration,silicification,phyllic alteration（quartz-sericite-pyrite alteration）and argillic alteration（mainly Kaolinitization and illite-hydromuscovitization,always overlapping the silicic zone and phyllic zone）.The main characteristics of mineralization,most founded in the ore district,are molybdenite-bearing vein,stockwork quartz＋molybdenite±sulfide（other gangue minerals）vein,and ribbon-textured quartz＋molybdenite±pyrite vein.Less disseminated mineralization,pure molybdenite veinlets and spotted mineralized matrix in the magmatic-hydrothermal breccias are observed in the Sharang area.As the phyllic zone and argillic zone are both main alteration types in the field study of Sharang,low erosion level of this porphyry deposit suggests great potential for the exploration.Additionally,several world-wide,typical porphyry molybdenum deposits are selected for the comparison and discussion of their characteristics of alteration and mineralization in this paper.It is concluded that both of potassic-silicate alteration and phyllic alteration have the major tight connection with mineralization in the most porphyry molybdenum deposits,and some alteration zones consist of fluorine-bearing minerals,such as the topaz zone in Henderson and fluorite-bearing zone in Donggou.The comparisons also indicate that the geometries of orebodies in most porphyry molybdenum deposits have been found as layers of coating ore-shell（or called inverted-cup）in the top of ore-forming intrusion.Among the orebodies,the main patterns of mineralization are stockwork and ribbon-textured quartz＋molybdenite veins,and both vein-type and breccia-r

关 键 词：冈底斯北缘 沙让斑岩钼矿 蚀变 矿化 典型斑岩钼矿床对比 

分 类 号：P618.51[天文地球—矿床学]