Metamorphic evolution of the East Tethys tectonic domain and its tectonic implications  

作　　者：Qiangqiang ZHANG Xiaoying GAO Renxu CHEN Yongfei ZHENG 

机构地区：[1]School of Earth and Space Sciences,Universiy of Science and Technology of China,Hefei 230026,China [2]Key Laboraiory of Crust-Mantle Materials and Environments,Chinese Academy of Sciences,Hefei 230026,China [3]Center of Excellence for Comparative Planetology Chinese Academy of Sciences,Hefei 230026,China

出　　处：《Science China Earth Sciences》2023年第12期2686-2711,共26页中国科学（地球科学英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant No.92155306)。

摘　　要：The China Central Orogenic System(CCOS),extending in an east-west direction in the middle part of China,is composed of the Early Paleozoic Altyn-North Qilian-North Qaidam-East Kunlun-North Qinling-North Tongbai orogens in the west and the Late Paleozoic to Early Mesozoic South Tongbai-Hong'an-Dabie-Sulu orogens in the east.They were produced by oceanic subduction and continental subduction/collision during the closure of the Proto-Tethys and the Paleo-Tethys oceans,respectively.Different types of metamorphic rocks with various ages are extensively exposed in these orogens,and they were produced at different geothermal gradients in different stages during the tectonic evolution of convergent continental margins,making them ideal targets to reconstruct the spatiotemporal evolution of the Eastern Tethys tectonic domain.In this article,an integrated study of metamorphic temperature(T)-pressure(P)-time(t)records is presented for metamorphic rocks along the CCOS,aiming to ascertain the change of metamorphic T/P ratios in both time and space,and then shed light on the tectonic evolution of the East Tethys tectonic domain in association with the thermal state change of convergent continental margins.The results indicate that despite the difference in metamorphic ages,metamorphic rocks in different orogens show a common trend with clockwise P-T-t paths.With respect to plate convergence for subduction and collision,regional metamorphism is categorized into three stages:(1)an early convergent stage,corresponding to low T/P Alpine-type blueschist-to eclogite-facies high-P to ultrahigh-P metamorphism;(2)a later convergent stage,corresponding to the medium T/P Barrovian-type medium-P amphibolite to high-P granulite-facies metamorphism;and(3)a post-convergent stage,corresponding to the high T/P Buchan-type lowP amphibolite to MP granulite-facies metamorphism.Nonetheless,a few metamorphic rocks only record a two-sage metamorphic evolution,with an early Barrovian-type high-P granulite-facies metamorphism and a late Buchan-type lo

关 键 词：Tethys tectonics Oceanic closure Crustal metamorphism Geothermal gradient Intracontinental rifting 

分 类 号：P542[天文地球—构造地质学]