Geodynamics of oceanic plateau and plume head accretion and their role in Phanerozoic orogenic systems of China

作     者：Peter G.Betts Louis Moresi Meghan S.Miller David Willis 

作者机构：School of EarthAtmosphere and EnvironmentMonash UniversityClayton Campus School of Mathematical SciencesMonash UniversityClayton Campus Department of Earth SciencesUniversity of Melbourne Department of Earth SciencesUniversity of Southern California 

出 版 物：《Geoscience Frontiers》 (地学前缘（英文版）)

年 卷 期：2015年第6卷第1期

页      面：49-59页

核心收录：

学科分类：070904[理学-构造地质学] 0709[理学-地质学] 07[理学] 

基　　金：Monash Research Acceleration Program,which funded part of the research support from the Australian Research Council's Discovery Projects funding scheme(projects Nos.DP130101946 and DP110101697) use of the NCI National Facility in Canberra, Australia,which is supported by the Australian Commonwealth Government NSFCAREER award EAR-1054638 

主　　题：Subduction Accretion Plateau Plume Central Asian Orogen Geodynamics 

摘      要：We present three 3D numerical models of deep subduction where buoyant material from an oceanic plateau and a plume interact with the overriding plate to assess the influence on subduction dynamics, trench geometry, and mechanisms for plateau accretion and continental growth. Transient instabilities of the convergent margin are produced, resulting in： contorted trench geometry; trench migration parallel with the plate margin; folding of the subducting slab and orocline development at the convergent margin; and transfer of the plateau to the overriding plate. The presence of plume material beneath the oceanic plateau causes fiat subduction above the plume, resulting in a ＂bowed＂ shaped subducting slab. In plateau-only models, plateau accretion at the edge of the overriding plate results in trench migration around the edge of the plateau before subduction is re-established directly behind the trailing edge of the plateau. The plateau shortens and some plateau material subducts. The presence of buoyant plume material beneath the oceanic plateau has a profound influence on the behaviour of the convergent margin. In the plateau ~ plume model, plateau accretion causes rapid trench advance. Plate convergence is accommodated by shearing at the base of the plateau and shortening in the overriding plate. The trench migrates around the edge of the plateau and subduction is re-established well behind the trailing edge of the plateau, effectively embedding the plateau into the overriding plate. A slab window forms beneath the accreted plateau and plume material is transferred from the subducting plate to the over- riding plate through the window. In all of the models, the subduction zone maintains a relatively stable configuration away from the buoyancy anomalies within the downgoing plate. The models provide a dynamic context for plateau and plume accretion in Phanerozoic accretionary orogenic systems such as the East China Orogen and the Central Asian Orogen （Altiads）, which ar