青海红沟地区哈曼大阪花岗岩体锆石LA-ICP-MS测年——对红沟铜矿床形成时代和成因的认识  

A LA-ICP-MS U-Pb Dating of Zircons from the Hamandaban Granite Body in the Honggou Area,Qinghai Province:New Evidence for Metallogenic Age and Causes of the Honggou Copper Polymetallic Deposit

作　　者：余吉远[1] 李向民[1] 王国强[1] 武鹏[1] 

机构地区：[1]中国地质调查局西安地质调查中心,西安710054

出　　处：《地质与勘探》2010年第4期592-598,共7页Geology and Exploration

基　　金：青藏专项"北祁连成矿带成矿条件研究与找矿靶区优选"(编号:1212010818090);中国地质调查局大调查项目"中亚古生代火山岩形成机制及其与成矿关系研究"(编号:1212010611804)资助

摘　　要：哈曼大阪花岗岩体位于北祁连造山带-中祁连造山带接壤地带。结合阴极发光,对哈曼大阪花岗岩体花岗闪长岩中的锆石进行了LA-ICP-MSU-Pb同位素测年。获得单颗粒锆石的微区U-Pb年龄为478.8±1.2Ma。认为哈曼大阪花岗岩体形成时代为早奥陶世。获得的红沟铜矿直接赋矿围岩双峰式火山岩中基性火山岩的LA-ICP-MS锆石U-Pb同位素年龄为443.2±1.2Ma,认为红沟铜多金属矿床形成时代为晚奥陶世。因此,认为哈曼大阪花岗岩体与红沟铜矿没有成因上的联系。这一认识,对进一步深入研究祁连造山带陆缘裂谷环境的Cu多金属矿床的成矿时代及成因具有重要意义。The Hamandaban granite body lies in contiguous area of the northern-middle Qilian orogenic belt. Based on the cathodoluminescence micrography, the petrogenic age is obtained by the LA-ICP-MS U-Pb isotope dating on the zircons from the granodiorite in this rock body. The yielded U- Pb age is 478.8±1.2Ma,indicating the early Ordovician. The formation age of basic volcanic rocks from the bimodal volcanic rock which is ore-hosting rock measured by U-Pb method is 443.2±1.2Ma in the Honggou copper polymetallie depost,indicating the late Ordovician. We consider that there is no genetic connection between the Hamandaban granite body and the Honggou copper polymetallic depost. This cognition is of great significance in further research on the metallogenic epoch and genesis of copper polymetallic deposits occurring in a continental margin rill environment in the Qilian orogenic belt.

关 键 词：花岗闪长岩 锆石U—Pb年代学 LA—ICP—MS 红沟 青海 

分 类 号：P597.3[天文地球—地球化学]