那拉提复合岛弧带泥盆纪-石炭纪侵入岩特征及意义——南天山洋消亡的证据

The Devonian-carboniferous Intrusive Rocks's Characteristics and it's Significance in Early Paleozoic Composite Island arc zone of Nalati-Evidence of the South Tianshan Ocean's demise

西天山巴音布鲁克北部那拉提早古生代复合岛弧带中侵入岩体主要由晚泥盆纪角闪二长岩、中细粒黑云母二长花岗岩和早石炭纪中粒闪长岩、石英二长斑岩、二长花岗岩、碱长花岗岩组成。本文从岩石岩相学特征、主微量及稀土元素特征方面,阐明岩体成因及形成构造背景,从而间接证明南天山洋于晚古生代初期古生代洋盆的消减、闭合以及早古生代洋盆关闭后的大规模石炭-二叠纪裂谷拉伸事件,在二叠纪晚期真正进入到陆内演化阶段。

Early Paleozoic composite island arc zone of Nalati, which is located on the north of Bayinbluk. Its intrusive rocks are main composed of late devonian hornblende monzonite, fine-grained biotite monzonite granite, early carboniferous grained diorite, quartz monzonite porphyry, adamellite and alkali feldspar granite. From the aspects that petrographic characteristics, characteristics of main and trace elements, and REE characteristics, this article expounds the causes of formation and geotectonic setting of the main intrusive rock. Thereby indirectly prove the facts that the South Tianshan Ocean＇s reduction and closure in late Paleozoic early Paleozoic, Large- scale carboniferous - Permian rift valley stretching after the Early Paleozoic ocean basin closed. So the South Tianshan Ocean really entered the stage of intracontinental evolution in the late Permian.