Double subduction of the Early Paleozoic North Qilian oceanic plate: Evidence from granites in the central segment of North Qilian, NW China
Double subduction of the Early Paleozoic North Qilian oceanic plate: Evidence from granites in the central segment of North Qilian, NW China
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发表时间：
2006
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通讯作者：
Wu Cai-lai
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作者：
Wu Cai-lai
本文对北祁连山中段牛心山花岗岩和民乐老沟花岗岩进行了锆石SHRIMP定年。测年结果表明，牛心山花岗岩和民乐老沟花岗岩的年龄分别为476 Ma和463 Ma。岩石化学表明，牛心山花岗岩和民乐老沟花岗岩均具有活动大陆边缘岩浆的特征。在此基础上，结合花岗岩产状的构造位置和野外观测资料，认为北祁连大洋板块南向和北向俯冲发生在早古生代。其中向南俯冲形成泥心山花岗岩(476 Ma)，向北俯冲形成民乐老沟花岗岩(463 Ma)。
This paper deals with zircon SHRIMP dating of the Niuxinshan and Minleyaogou granites in the central segment of the North Qilian Mountains,NW China.The dating results indicate that the ages of the Niuxinshan granite and Minleyaogou granite are 476 and 463 Ma respectively.Petrogeochemistry shows that both granite intrusions have the features of active continental-margin magmatism.On the basis of these features, combined with the tectonic locations of granite occurrence and field observation data,the authors think that south- and north-directed subductions of the North Qilian oceanic plate took place in the Early Paleozoic,of which the southward subduction resulted in the formation of the Nixinshan granite (476 Ma) and the northward subduction gave rise to the Minleyaogou granite (463 Ma).