CAJ | 학술논문

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。
내몽고적봉오한기일대적조토구조유변기성암、변질산성화산암협운모석영편암조성。채용LA-ICP-MS기술，대조토구조2건변류문암양품진행료U-Pb동위소측정，획득적고석206Pb/238U년령가권평균치분별위359.4±1.4Ma화360.3±1.4Ma，즉만니분세법문기，표명조토구조형성우만니분세，이비전인인위적조석탄세。조토구조화산암석조합위변현무암화변류문암，현시출전형적쌍봉식화산암특정，게시해구재만니분세처우신전구조배경。
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 tec?tonically. The volcanic rocks of the Chaotugou Formation consist of basalts and rhyolites. LA-ICP-MS zircon U-Pb dating of rhyo?lite 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 associa?tion and implying an extensional environment.