Mid-ocean ridges and subduction zones are two end-member geological unites,representing divergent and convergent plate boundaries,respectively.These two tectonic units are not isolated in nature,instead,intensive interaction is present between mid-ocean ridges and subduction zones.In this study,we documented a popular way of mid-ocean ridge-subduction interaction,i.e.,subduction with the involve of mid-ocean ridges.We summarized how mid-ocean ridges involve in subduction with particular attention paid on the three possible patterns,i.e.,ridge-inversed subduction under plate compression likely due to the change in plate motion,competition in subduction between mid-ocean ridges and other(intra-oceanic or continental marginal)tectonic units,and the input of mid-ocean ridges into subduction zones.We reviewed the related geodynamical numeric modeling studies that provide new insights on subduction dynamics with the involve of mid-ocean ridges.(1)Ridge-inversed subduction could occur in nature with the possible examples including the Izanagi-Pacific ridge,the Proto South China Sea ridge,the Yap trench,and the Macquarie complex ridge system.Numerical models investigated the dynamics of ridge-inversed subduction under tectonic compression,and revealed that the thermal structure and weak rheological strength of mid-ocean ridges are the key factors.However,subduction through the inversion of extinct mid-ocean ridges becomes difficult,because of its increased strength due to thermal diffusion after the cease of spreading.(2)Natural examples of ridge-inversed subduction are relatively few,and a possible reason is the competition in subduction between mid-ocean ridges and other intra-oceanic or continental marginal tectonic units(e.g.,oceanic detachment fault,transform faults,passive margins)under plate compression.Competition in subduction between mid-ocean ridges and passive margins is investigated in the previous numerical modeling studies,and the key physical parameters affecting the competition in subduction initiation include the cooling age of mid-ocean ridges,the rheological strength of passive margins,the plate convergence rate and the oceanic plate age.Competition in subduction between mid-ocean ridges and oceanic detachment faults or transform faults is investigated numerically,but more sophisticated numerical studies(especially in three dimension)are needed.(3)The mid-ocean ridges that failed to initiate subduction zones through ridge inversion are likely transported to subduction zones attached to the subducting plates,evidenced by the natural examples along the western and eastern margins of the Pacific Ocean.The two end-member patterns of the input of mid-ocean ridges into subduction zones are trench parallel and trench orthogonal,leading to distinct dynamics of subduction.Subduction dynamics with trench parallel input of mid-ocean ridges(e.g.,the input of the Izanagi-Pacific mid-ocean ridge into the subduction zones along the western Pacific margin)could be simulated with 2D models,and the previous 2D numerical study suggested that the input of a mid-ocean ridge into the subduction zone with steep slab leads to slab breakoff and the formation of two phases of subduction,while the input of a mid-ocean ridge into the subduction zone with flat slab results in ridge subduction with the formation of intra-plate magmatism.Trench orthogonal input of mid-ocean ridges into subduction zones could produce slab tear with the formation of slab windows,but whether active or extinct mid-ocean ridges affect slab tear need to be investigated with 3D models in the future studies.Additional patterns of subduction with the involve of mid-ocean ridges(e.g.,oblique input of mid-ocean ridges into subduction zones,competition in subduction between mid-ocean ridges and transform faults)should be explored numerically in the future studies.
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