内蒙古敖汉旗朝吐沟组火山岩LA-ICP-MS锆石U-Pb年龄  

LA-ICP-MS zircon U-Pb ages of the volcanoic rocks from the Chaotugou Formation in Aohan Banner, Inner Mongolia

作　　者：孙立新 任邦方 滕飞 张永 谷永昌[1] 郭虎 

机构地区：[1]中国地质调查局天津地质调查中心,天津300170

出　　处：《地质通报》2015年第8期1493-1501,共9页Geological Bulletin of China

基　　金：中国地质调查局项目(编号:1212011121078)

摘　　要：内蒙古赤峰敖汉旗一带的朝吐沟组由变基性岩、变质酸性火山岩夹云母石英片岩组成。采用LA-ICP-MS技术,对朝吐沟组2件变流纹岩样品进行了U-Pb同位素测定,获得的锆石206Pb/238U年龄加权平均值分别为359.4±1.4Ma和360.3±1.4Ma,即晚泥盆世法门期,表明朝吐沟组形成于晚泥盆世,而非前人认为的早石炭世。朝吐沟组火山岩石组合为变玄武岩和变流纹岩,显示出典型的双峰式火山岩特征,揭示该区在晚泥盆世处于伸展构造环境。LA-ICP-MS zircon U-Pb dating of the metavolcanic rocks from the Chaotugou Formation in Chifeng-Aohan Banner area of Inner Mongolia was carried out in this paper. The study area is located on the north margin of the North China Craton tectonically. The volcanic rocks of the Chaotugou Formation consist of basalts and rhyolites. LA-ICP-MS zircon U-Pb dating of rhyolite yielded U-Pb ages of between 359.4±1.4Ma and 360.3±1.4Ma, representing the time of crystallization of the volcanic rocks. The dating result reveals that the rhyolite from the Chaotugou Formation was formed in Late Devonian rather than in Early Carboniferous as previously thought. The Late Devonian volcanic rocks are basalts and rhyolites, suggesting a typical bimodal volcanic rock association and implying an extensional environment.

关 键 词：朝吐沟组火山岩 LA-ICP-MS锆石U-PB年龄 晚泥盆世 内蒙古敖汉旗 

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