On the Role of Dual Active Margin Collision for Exhuming the World's Largest Ultrahigh Pressure Metamorphic Belt

作     者：王璐 Timothy M Kusky M Santosh 

作者机构：State Key Laboratory for Geological Processes and Mineral ResourcesChina University of Geosciences Three Gorges Geo-hazard Research Center of Ministry of EducationChina University of Geosciences China University of Geosciences 

出 版 物：《Journal of Earth Science》 (地球科学学刊（英文版）)

年 卷 期：2012年第23卷第6期

页      面：802-812页

核心收录：

学科分类：070902[理学-地球化学] 0709[理学-地质学] 07[理学] 

基　　金：supported by the National Natural Science Foundation of China (Nos.91014002,40821061,40802045) the Science Foundation of Shandong Province,China (No.Q2008E03) the Special Financial Grant from China Postdoctoral Science Foundation (No.201104495) Ministry of Education of China (No.B07039) 

主　　题：ultrahigh-pressure metamorphic belt plate tectonics subduction collision exhumation,Qinling-Dabieshan-Sulu belt. 

摘      要：ABSTRACT： A wide variety of tectonic models have been invoked to explain the exhumation of the world＇s largest ultrahigh pressure （UHP） orogenic belt, the Qinling Dabieshan Sulu belt in China, and its correlatives in Korea. Most of these models assume that the orogen contains one main collisional suture between the North and South China cratons that collided in the Mesozoic. New field data reveal that this model is too simplistic, and that the collision involved an additional mi- croplate, which initially rifted off the Yangtze craton. This continental microplate was partially sub- ducted beneath an active margin on the North China craton, and subsequently an additional active Andean-style margin developed on the southern margin of the Qinling microplate after collision, leav- ing the near-vertical microplate wedged between the two thickened and thermally softened margins. The thermo-mechanical environment of collision thus left a cold, thick, and buoyant microplate wedged between two easily deformed margins, which acted as power-law creep channels, accommodating rapid buoyancy-driven rise of a 2 000 km long wedge of the subducted microplate, which became intimately involved with the collisional process. An addi- tional segment of the northern Yangtze craton was subducted to ~100 kin, and formed a separate wedge that rose alongside the thermally softened margin of the Qinling mieroeontinent, and was bordered on the south by the recently thermally- softened rift zone where the Qinling mieroeonti- nent broke off the Yangtze eraton between Late Devonian and Permian times. Recognizing the dual active margins in Qinling-Dabieshan-Sulu orogen and the thermally-softened power-law creep channels sheds new light on understanding exhumation of the world＇s largest ultrahigh pressure belt. We propose that this model is generally applicable to other UHP belts worldwide.