中亚造山带东南缘从俯冲-增生到碰撞的构造-岩浆演化记录  

Tectono-magmatic evolution from accretion to collision in the southern margin of the Central Asian Orogenic Belt

作　　者：李舢 王涛[2] 肖文交[1,3] 侯泉林 LI Shan;WANG Tao;XIAO WenJiao;and HOU QuanLin(College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;Beijing SHRIMP Center,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China;Xinjiang Research Center for Mineral Resource,Xinjiang Institute of Ecology and Geography,Chinese Academy of Sciences,Urumqi 830011,China)

机构地区：[1]中国科学院大学地球与行星科学学院,北京100049 [2]北京离子探针中心,中国地质科学院地质研究所,北京100037 [3]中国科学院新疆生态与地理研究所,新疆矿产资源研究中心,乌鲁木齐830011

出　　处：《岩石学报》2023年第5期1261-1275,共15页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(42161144007、41772232);中国科学院大学中央高校基本科研业务费专项资金(E2EG0401X2)联合资助.

摘　　要：造山带演化及增生到碰撞的转变是板块构造与大陆动力学研究中的前沿科学问题。中亚造山带被认为是古亚洲洋长期俯冲-增生演化形成的显生宙最大的增生造山带,以发育巨量的面状展布的俯冲-增生相关的弧岩浆岩为特征。并且,由于中亚增生型造山带在潘吉亚最后聚合过程中发生弧弧(陆)碰撞,因此缺乏大规模且跨构造单元的碰撞相关的构造和变质等物质标志。显然,能否识别出大洋闭合期间碰撞作用的岩浆标志成为确定增生造山带增生过程终止的关键之一。本文系统研究确定:中亚造山带东南缘二叠纪到三叠纪钙碱性-碱钙性岩浆在空间分布上显示出由北西向南东迁移演化的特征;在岩浆性质上具有从二叠纪新生地壳来源的弧岩浆向早-中三叠世碰撞挤压背景下古老陆壳组分逐渐增多的高Sr/Y岩浆以及晚三叠世后造山伸展相关的A型花岗岩演化的特征。这些特征提供了俯冲-增生向碰撞造山演变的关键岩浆岩证据。结合区域资料,厘定出增生造山带最后碰撞相关的标志性岩浆为沿缝合带呈零星线性展布的增厚下地壳源区的高Sr/Y花岗岩类,构建了中亚造山带南缘从双向俯冲-增生到增生楔-增生楔碰撞及后造山伸展的三阶段构造-岩浆演化模型。系统对比研究,揭示出增生-碰撞相关的岩浆记录沿横向展布在中亚造山带南缘甘肃北山到吉林中部一带,表明碰撞挤压相关的岩浆作用在中亚造山带南缘具有一定的普适性。中亚造山带南缘从增生到碰撞的岩浆演化记录的厘定,证实显生宙最大的巨型增生造山带演化末期经历了碰撞造山作用,对进一步深入探索增生造山演化末期碰撞相关的标志性岩浆具有重要意义。The global orogenic belts have undergone accretionary and collisional orogenic processes to varying degrees.Then,how accretion evolves into the collision is a frontier scientific question for plate tectonics and continental dynamics.The Central Asian Orogenic Belt(CAOB)is the largest Phanerozoic accretionary orogenic belt by the long-term subduction-accretionary evolution related to the Paleo-Asian Ocean.Its late evolution stage is relatively short of collision-related tectonic and metamorphic records.So,whether a collision-related magmatic record develops is still an open question.The magmas in the southeastern margin of the CAOB were characterized by calc-alkaline and alkali-calc and migrated from the northwest to the southeast.These magmas are also indicated by evolution from the Permian arc magma to the Early-Middle Triassic collision-related high Sr/Y magma derived from the old crust and A-type granites associated with the Late Triassic post-orogenic extension.This study provides critical magmatic evidence for the evolution of subduction-accretion to collisional orogenesis.Combined with the regional geology,we have determined that the signature magma associated with the last collision of the CAOB is the high Sr/Y granite derived from the thickened lower crust and scattered linearly along the suture zone.A three-stage tectonic-magmatic evolution model from discrete bidirectional subduction-accretion to accretionary wedge-accretionary wedge-collision and post-orogenic extension was proposed in the southern margin of the CAOB.The collision-related magmatic records are distributed laterally from Beishan of Gansu Province to the central part of Jilin Province,indicating that the collision-related magmatism has good generality in the southern margin of the CAOB.The clarification of the magmatic evolution records from accretion to collision during the late CAOB evolution reveals that the largest Phanerozoic accretionary orogenic belt experienced different tectonic deformation of compress,strike-slip and extension a

关 键 词：增生造山带 软碰撞 离散型双向俯冲 高Sr/Y花岗岩 中亚造山带 

分 类 号：P541[天文地球—构造地质学]