Dynamics of thinning and destruction of the continental cratonic lithosphere: Numerical modeling

作     者：Mingqi LIU Zhonghai LI 

作者机构：Key Laboratory of Computational Geodynamics College of Earth and Planetary Sciences University of Chinese Academy of Sciences Institute of Geology Chinese Academy of Geological Sciences 

出 版 物：《Science China Earth Sciences》 (中国科学（地球科学英文版）)

年 卷 期：2018年第61卷第7期

页      面：823-852页

核心收录：

学科分类：070904[理学-构造地质学] 070801[理学-固体地球物理学] 0709[理学-地质学] 07[理学] 0708[理学-地球物理学] 

基　　金：supported by the National Natural Science Foundation of China (Grant Nos. 41622404, 41688103) the Strategic Priority Research Program (B) of Chinese Academy of Sciences (Grant No. XDB18000000) the National Key Basic Research and Development Program of China (Grant No. 2015CB856106) 

主　　题：Lithospheric thinning Cratonic destruction Big mantle wedge Plate subduction Fluid migration Numericalmodeling 

摘      要：Thinning of the cratonic lithosphere is common in nature, but its destruction is not. In either case, the mechanisms for both thinning and destruction are still widely under debate. In this study, we have made a review on the processes and mechanisms of thinning and destruction of cratonic lithosphere according to previous studies of geological/geophysical observations and numerical simulations, with specific application to the North China Craton(NCC). Two main models are suggested for the thinning and destruction of the NCC, both of which are related to subduction of the oceanic lithosphere. One is the bottom-up model, in which the deeply subducting slab perturbs and induces upwelling from the hydrous mantle transition zone(MTZ). The upwelling produces mantle convection and erodes the bottom of the overriding lithosphere by the fluid-meltperidotite reaction. Mineral compositions and rheological properties of the overriding lithospheric mantle are changed, allowing downward dripping of lithospheric components into the asthenosphere. Consequently, lithospheric thinning or even destruction occurs. The other is the top-down model, characterized by the flat subduction of oceanic slab beneath the overriding cratonic lithosphere. Dehydration reactions from the subducting slab would significantly hydrate the lithospheric mantle and decrease its rheological strength. Then the subduction angle may be changed from shallow to steep, inducing lateral upwelling of the asthenosphere. This upwelling would heat and weaken the overriding lithospheric mantle, which led to the weakened lithospheric mantle dripping into the asthenosphere. These two models have some similarities, in that both take the subducting oceanic slab and relevant fluid migration as the major driving mechanism for thinning or destruction of the overriding cratonic lithosphere. The key difference between the two models is the effective depth of the subducting oceanic slab. One is stagnation and flattening in t