云南哀牢山构造带仰宗流纹斑岩锆石U-Pb年龄、地球化学特征及其构造意义  

Petrogeochemistry and zircon U-Pb chronology of the Yangzong rhyolite porphyry along Ailao Mountain tectonic belt

作　　者：孙崇波[1,2] 李忠权[1] 王道永[1] 许远平 李滔 赵云川 

机构地区：[1]国土资源部构造成矿成藏重点实验室(成都理工大学)/油气藏地质及开发工程国家重点实验室(成都理工大学),四川成都610059 [2]四川冶金地质勘查局水文工程大队,四川成都611730

出　　处：《地质通报》2017年第2期190-198,共9页Geological Bulletin of China

基　　金：中国地质调查局项目<西南三江成矿带南段基础地质调查>(编号:1212010880406;1212011120582)

摘　　要：对云南绿春县仰宗流纹斑岩进行了锆石U-Pb年龄、岩石地球化学分析。LA-ICP-MS锆石U-Pb测年显示,仰宗流纹斑岩年龄为263.1±2.3Ma,形成于晚二叠世。岩石地球化学分析显示,仰宗流纹斑岩SiO_2含量为71.08%~80.26%,全碱(Na_2O+K_2O)含量为4.67%~8.67%,且Na_2O<K_2O;岩石轻、重稀土元素存在一定的分馏,负Eu异常明显(δEu=0.05~0.57),相对富集Rb、Th、U、Ni、Cs、Zr、Hf、As、K等元素,亏损Sr、Ta、Ba、Cr、Zn、W等元素。结果显示,仰宗流纹斑岩形成于碰撞期后的陆内构造环境,表明哀牢山构造带的古特提斯支洋或弧后盆地在晚二叠世(263.1±2.3Ma)可能已经闭合。This paper presents bulk petrogeochemistry and zircon U-Pb dating results for the Yangzong rhyolite porphyry in Luchun County, Yunnan Province. LA-ICP-MS zircon U-Pb dating results show that the Yangzong rhyolite porphyry was formed in the Late Permian(263.1±2.3Ma). The Yangzong rhyolite porphyry is characterized by SiO_2 content of 71.08%~80.26%, alkali(Na_2O+K_2O) 4.67%~8.67%, and Na_2O<K_2O. It is enriched in LREE and Rb, Th, U, Ni, Cs, Zr, Hf, As, K and depleted in Sr, Ta, Ba, Cr,Zn, W with negative Eu anomalies(δEu=0.05~0.57). According to the diagrams, the Yangzong rhyolit porphyry was formed in the tectonic environment of island arc-continent or continental-arc collision,indicating that the branch of Paleo-Tethys Ocean or arc basin in Ailao Mountain tectonic belt might have been closed in the Late Permian(263.1±2.3Ma).

关 键 词：流纹斑岩 LA-ICP-MS锆石U-PB年龄 岩石地球化学 板内型花岗岩 

分 类 号：P588.14[天文地球—岩石学] P597.3[天文地球—地质学]