摘要
阿奇山—雅满苏带位于东天山南部,属于中亚造山带的重要组成部分,其内发育大量岩浆岩,形成时代主要为石炭纪—二叠纪。目前为止,尚未有早期岩石的报道。对位于该区南缘的二长花岗岩进行了LA-MC-ICP-MS锆石U-Pb同位素测年研究。结果显示,二长花岗岩中锆石呈自形—半自形,具有明显的振荡环带,Th/U值均大于0.4,显示岩浆锆石特征。这些锆石的^(206)Pb/^(238)U年龄加权平均值为374.7±4.0 Ma(MSWD=0.7,n=17),代表岩浆结晶年龄。表明研究区存在晚泥盆世岩浆事件,阿奇山—雅满苏带的形成至少开始于晚泥盆世。二长花岗岩的形成时代和中天山晚泥盆世岛弧环境岩浆岩形成时代一致,表明其可能是古大洋板片向南俯冲的产物。
The Aqishan-Yamansu belt,located at south of the Eastern Tianshan belt,is a pivotal part of the Central Asian orogenic belt.The most important feature of the Aqishan-Yamansu belt is the occurrence of voluminous igneous rocks,which mainly formed during Carboniferous and Permain with no pre-Carboniferous age has been reported.We present zircon LA-MC-ICP-MS U-Pb chronology of monzogranite,discovered on the southern margin of the Aqishan-Yamansu belt.The zircons from the monzogranite are mostly euhedral to subhedral,with oscillatory zoning and Th/U ratios more than 0.4,suggesting magmatic origin.Therefore,the obtained weighted mean ^(206)Pb/^(238)U age of 374.7±4.0 Ma(MSWD=0.7,n=17)can be used to represent the magma crystallization age.This result suggests that a magmatic event occurred during Late Devonian and formation of the Aqishan-Yamansu belt possibly began in Late Devonian at latest.Combined with the Late Devonian magmatism formed in arc environment in Central Tianshan,we concluded that the monzogranite may have been produced by the southward subduction of ancient oceanic plate beneath the Central Tianshan during Late Devonian.
作者
蔡宏明
王蓉
刘桂萍
宫相宽
CAI Hongming;WANG Rong;LIU Guiping;GONG Xiangkuan(College of Geology and Mining Engineering,Xinjiang University,rümqi 830047,Xinjiang,China;Geography Postdoctoral Research Station,Xinjiang University,rümqi 830047,Xinjiang,China;Faculty of Land Resource Engineering,Kunming University of Science and Technology,Kunming 650093,Yunnan,China)
出处
《地质通报》
CAS
CSCD
北大核心
2022年第7期1184-1190,共7页
Geological Bulletin of China
基金
新疆维吾尔自治区高校科研计划项目《中天山北缘三叠纪埃达克质花岗岩的发现及地质意义》(编号:XJEDU2020Y005)
中国博士后科学基金资助项目《东天山雅满苏地区印支期花岗岩类成因及构造意义》(编号:2017M613257)。
