伊犁板块南缘高T/P变质岩系:代表前寒武纪结晶基底还是活动大陆边缘?  

High T/P Metamorphic Rocks in Southern Yili Plate:Representative for Precambrian Crystalline Basement or Active Continental Margin?

作　　者：夏彬 张立飞[2] Xia Bin;Zhang Lifei(School of Earth Sciences,China University of Geosciences,Wuhan 430074,China;School of Earth and Space Sciences,Peking University,Beijing 100871,China)

机构地区：[1]中国地质大学地球科学学院,湖北武汉430074 [2]北京大学地球与空间科学学院,北京100871

出　　处：《地球科学》2021年第6期1960-1972,共13页Earth Science

基　　金：国家自然科学基金青年基金项目(No.41502043).

摘　　要：新疆伊犁板块南缘的狭长地带内广泛出露了高T/P变质岩系,其成因和属性研究有利于我们深入了解天山造山带的造山演化过程.前人认为这些岩石属早前寒武纪结晶基底,近期研究则显示其主要形成于早古生代.系统总结了课题组近些年在该区开展的工作,结合前人研究,对伊犁板块南缘不同岩石构造单元内的岩石成因进行了分析和讨论,提出伊犁板块南缘的高T/P变质岩系的形成与南天山洋大洋板片在伊犁板块之下的俯冲、岩浆在陆缘弧位置就位并造成伊犁板块南缘地温梯度的明显升高有关.因此,认为伊犁板块南缘狭长地带内的高T/P变质岩系形成于南天山洋俯冲过程中形成的活动大陆边缘环境,而非前寒武纪结晶基底的组成部分.Study on high T/P metamorphic rocks in the southern Yili plate is essential for our understanding of the evolution of the Tianshan orogenic belt.Previous researchers suggested these rocks to belong to the Early Precambrian basement of the Nalati Group.However,recent studies show that they were generated in Paleozoic.Here in this study,it discusses the origin and formation environment for rocks in different litho-tectonic units in the southern Yili plate.Combined with other studies,it proposes that the high T/P metamorphic rocks were formed due to the emplacement and transportation of large volume magma in the arc region when the South Tianshan oceanic slab subducted under the Yili plate.The magma intrusion significantly elevated the thermal gradient,resulted in the regional high T/P metamorphism along the southern Yili plate.Therefore,high T/P rocks in the southern Yili plate were not a constituent of the Early Precambrian basement,but represented an active continental margin formed by the subduction of the South Tianshan ocean.

关 键 词：伊犁板块南缘 高T/P变质岩单元 活动陆缘 岩石学 

分 类 号：P581[天文地球—岩石学]