东天山觉罗塔格一带晚古生代岩浆岩地球化学特征及构造意义

Geochemistry Characteristics and Tectonic Significance of the Igneous Rocks from the Eastern Tianshan Mountains

通过对东天山觉罗塔格一带晚古生代岩浆岩地质特征、岩石化学特征等系统研究,认为该晚古生代岩浆岩主要由早石炭世至中二叠世的火山岩和侵入岩组成,其形成与康古尔洋向北俯冲有关。早石炭世岩浆岩为康古尔洋初始俯冲而成的钙碱性岛弧火山岩及具有低压、低温特征的高钾钙碱性I型花岗岩;晚石炭世岩浆岩为后碰撞弧火山岩;早二叠世岩浆岩为具有后碰撞弧和板内双重特征的火山岩及高温、高压特征的I型花岗岩;中二叠世发育具有低压、高温特征的高钾钙碱性A型花岗岩。综合前人资料及本文研究成果,初步认为觉罗塔格一带晚古生代经历了俯冲碰撞—碰撞造山—造山后陆内伸展的构造演化过程。

This paper systematically summarized the geochemical characteristics of late Paleozoic igneous rocks in the Jueluotage area of Eastern Tianshan.The igneous rockis mainly formed by early Carboniferous to middle Permian volcanic and intrusive rocks,and its formation is relevant with the northward subduction of Kangguer ocean.The igneous rock of early Carboniferous is composed of calc-alkaline island arc volcanics formed in the initial stage of slab subduction and high-potassium calc-alkalineI-type granite with a characteristic of low temperature and low pres-sure.The igneous rock of late Carboniferous is post-collision arc volcanics.The igneous rock of early Permian is composed of the volcanic in the post-collision arc and intraplate environment,andI-type granite with a characteristic of high temperature and high pressure.The igneous rock of middle Permian is high-potassium calc-alkaline A-type granite with characteristics of high temper-ature and low pressure.The results of previous studies and this paper suggest that this region experienced a tectonic evolution from subduction-collision to collision-orogenesis and post-orogen-ic intracontinental extension in late Paleozoic.