Multistage evolution of continental collision orogen:A case study for western Dabie orogen  

作　　者：WU YuanBao State Key Laboratory of Geological Processes and Mineral Resources, Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, China State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi’an 710069, China 

出　　处：《Chinese Science Bulletin》2009年第15期2568-2579,共12页

基　　金：Supported by the National Basic Research Program of China (Grant No. 2009CB825000);National Natural Science Foundation of China (Grant Nos. 40873043, 40821061, 90714010 and 40772042);Ministry of Education of China (Grant Nos. IRT0441, B07039 and NCET-06-0659);Foundation of the State Key Laboratory of Continental Dynamics, Northwest University

摘　　要：The foramtion and evolution of collisional orogen is a prominent feature along convergent plate margins, and is generally a complex process. This article presents an integrated study of zircon genesis, U-Pb age and Lu-Hf isotope composition as well as geological characteristics for the western Dabie orogen to constrain its multi-stage evolution history. The results suggest that the formation of oceanic crust in the Huwan area was constrained at ca. 400―430 Ma, which was slightly later than the collision of the northern Qinling with the North China Block. It formed in a marginal basin in the northern margin of the Yangtze Block. The peak metamorphism of eclogite in the Huwan area occurred at ca. 310 Ma, and the timing of the initial exhumation of oceanic eclogite was about 270 Ma. The high to ultrahigh pressure (HP-UHP) metamorphic rocks in the Xinxian and the Hong'an metamorphic zones have the same ages and natures as those of the HP-UHP metamorphic rocks in the other Dabie-Sulu terrains, and also have experienced multi-stage exhumation, and thus can be taken as a coherent part of the Dabie-Sulu orogen. Therefore, the Qinling-Dabie-Sulu orogen is a typical multi-stage continental collision orogen, with an amalgamation process extending more than 200 Ma.The foramtion and evolution of collisional orogen is a prominent feature along convergent plate margins, and is generally a complex process. This article presents an integrated study of zircon genesis, U-Pb age and Lu-Hf isotope composition as well as geological characteristics for the western Dabie orogen to constrain its multi-stage evolution history. The results suggest that the formation of oceanic crust in the Huwan area was constrained at ca. 400--430 Ma, which was slightly later than the collision of the northern Qinling with the North China Block. It formed in a marginal basin in the northern margin of the Yangtze Block. The peak metamorphism of eclogite in the Huwan area occurred at ca. 310 Ma, and the timing of the initial exhumation of oceanic eclogite was about 270 Ma. The high to ultrahigh pressure （HP-UHP） metamorphic rocks in the Xinxian and the Hong＇an metamorphic zones have the same ages and natures as those of the HP-UHP metamorphic rocks in the other Dabie-Sulu terrains, and also have experienced multi-stage exhumation, and thus can be taken as a coherent part of the Dabie-Sulu orogen. Therefore, the Qinling-Dabie-Sulu orogen is a typical multi-stage continental collision orogen, with an amalgamation process extending more than 200 Ma.

关 键 词：大别造山带 大陆碰撞 西部 演变 超高压变质岩 碰撞造山带 苏鲁造山带 变质岩区 

分 类 号：P542[天文地球—构造地质学]