甘肃白银矿田基性火山岩的LA-ICP-MS同位素年代学  

A LA-ICP-MS chronological study of basic volcanics in Baiyin orefield,Gansu,China

作　　者：李向民[1] 马中平[1] 孙吉明[1] 余吉远[1] 

机构地区：[1]中国地质调查局西安地质矿产研究所,陕西西安710054

出　　处：《地质通报》2009年第7期901-906,共6页Geological Bulletin of China

基　　金：中国地质调查局青藏专项<北祁连成矿带成矿条件研究与找矿靶区优选>(编号:1212010818090);中国地质调查局地质大调查项目<中亚古生代火山岩形成机制及其与成矿关系研究>(编号:1212010611804);国家"305"项目<阿尔金山大型镁铁质层状杂岩体铜镍铂矿资源潜力调查及找矿靶区优选>(编号:006DAB07B03-021)资助

摘　　要：对白银矿田基性火山岩进行LA-ICP-MS法单颗粒锆石U-Pb年代学研究,查明白银矿田基性火山岩的成岩时代为465.0Ma±3.7Ma,相当于中奥陶世。结合前人的矿田酸性火山岩精确的同位素定年资料(467.3±2.9Ma和467.1±2.2Ma),认为白银矿田成矿时代为中奥陶世,含矿火山岩系形成于奥陶纪的岛弧—裂谷环境。这些成果对进一步深入研究白银矿田的构造演化和指导北祁连山白银式块状硫化物矿床的找寻具有重要意义。In this paper, LA-ICP-MS U-Pb isotope dating techniques were used to determine the metallogenic age,zircons from ba- sic volcanic rocks in Baiyin orefield. Giving average ^206Pb/^238U ages of 465.0±3.7Ma,this age should be Middle Ordovician. meta acid volcanic rocks with their predecessors volcanic accurate isotope data （about 467.3±2.9 Ma 和 467.1±2.2 Ma）, therefor,this age is the formation time of meta basic volcanic rocks, Formation environment of meta basic volcanic rocks is Island arc- continental rift environment in Ordovician. The findings are of great significance in furtherr research on the tectonic evolution of the North Qilian orogenic belt,the formation environment of the Baiyin type massive sulfide deposits, and the ore prospecting directions.

关 键 词：LA—ICP—MS 锆石U—Pb定年 基性火山岩 构造环境 白银矿田 

分 类 号：P588.145[天文地球—岩石学] P597.3[天文地球—地质学]