摘要
甲玛铜多金属矿床是冈底斯成矿带内产出的超大型矿床,其铜、钼、铅+锌、伴生金、伴生银资源量均达到大型及以上规模,该矿床也是成矿系列理论指导实践取得找矿突破的典型矿床。矿区的矽卡岩型主矿体呈层状、厚板状产于下白垩统林布宗组砂板岩、角岩(矿体顶板)与上侏罗统多底沟组灰岩、大理岩(矿体底板)的层间因推覆-滑覆构造引起的扩容空间内,矿体走向延长超过3000m,倾向延伸超过2200m,最大真厚度达250m。除了矽卡岩型铜多金属矿体是主要矿体类型外,矿区角岩型钼铜矿体与斑岩型钼铜矿体已经初具规模。角岩型矿体主要呈筒状分布于0～40线矽卡岩型矿体上部的角岩中,平面面积约0.8km2,矿体垂向最大延伸超过800m;斑岩型矿体已初见端倪,基本位于矽卡岩型矿体下部,但也有部分穿切矽卡岩型矿体。矿床中矿石的主要构造特征为浸染-细脉状,结构特征以热液交代作用形成的结构为主。矿石中主要的矿石矿物包括黄铜矿、斑铜矿、辉钼矿、黝铜矿和辉铜矿等,脉石矿石以矽卡岩矿物和石英为主。通过不同类型矿石中辉钼矿的Re-Os同位素测年,甲玛铜多金属矿床的形成时代介于18～10Ma之间,与青藏高原后碰撞伸展阶段成矿作用有关。稀土元素地球化学特征表明甲玛矿区矽卡岩是由斑岩结晶分异过程中分泌出的岩浆热液交代大理岩而形成。文章通过对甲玛铜多金属矿床地质、地球化学特征的详细分析和讨论,提出该矿床成因是与斑岩成矿作用有关的斑岩-矽卡岩-角岩型矿床。
The Jiama polymetallic copper deposit is a superlarge deposit in the Gangdese metallogenic belt in Tibet with large quantity resources of copper,molybdenum,lead＋zinc as well as associated gold and silver.It is also a typical deposit indicative of breakthrough in ore-search through the practice guided by the metallogenic series theory.The main skarn bodies are of layered and thick plate-like occurrence produced in the expansion space due to overthrust and sliding between the beds of K1l sand-slate,hornfels and of J3d limestone and marble.The main skarn body extends 3000m along the strike,and 2200m in the dipping direction,and its true thickness is up to 250m.The hornfels type molybdenum（copper）body and porphyry type molybdenum（copper）body both have a certain scale besides the main skarn body.The hornfels type bodies with tube-like form are distributed in the hornfels of the upper of the skarn body marked by 0~40 exploration lines with an area about 0.8 km2 on plane,extending 800m in vertical direction.The porphyry type bodies have an inkling of existence,which lie largely in the lower of skarn body or partially cutting through it.Disseminated-veinlets are main structure of ores,which are dominated by structure of thermal-liquid replacement.The primary ore minerals include chalcopyrite,bornite,molybdenite,tetrahedrite and chalcocite.The vein minerals are composed of skarn minerals and quartz.The molybdenite Re-Os age dating on different ores suggests that the Jiama polymetallic copper deposit formed between 18Ma and 10Ma,associated with mineralization in a post-collisional extensional setting in the Tibetan plateau.Its REE geochemical characteristics indicate that the Jiama skarn was generated by magmatic hydrothermal solution separated from magma replacing marble.Finally,through detailed analysis of geological and geochemical characteristics of the study area,this article suggests that it is a porphyry-skarn-hornfels type deposit associated with porphyry mineralization.
出处
《地质与勘探》
CAS
CSCD
北大核心
2010年第6期985-994,共10页
Geology and Exploration
基金
国家科技支撑项目(编号2006BAB01A01)
青藏专项(编号1212010818089)
西藏华泰龙矿业开发有限公司勘探项目
技术开发项目"西藏墨竹工卡县甲玛铜多金属矿床地质特征及找矿方向研究项目(E0804)
中央公益性行业科研专项(200911007-02)"共同资助
关键词
斑岩-矽卡岩-角岩型矿床
地质地球化学特征
矿床成因
甲玛铜多金属矿床
西藏
porphyry-skarn-hornfels type deposit
geological and geochemical characteristics
mineral genesis
Jiama polymetallic copper deposit
Tibet
