Compression at Strike‐Slip Fault Is a Favorable Condition for Subduction Initiation

• Published in: Geophysical research letters 2023-02, Vol.50 (4), p.n/a
• Main Authors: Zhong, Xinyi, Li, Zhong‐Hai
• Format: Article
• Language: English
• Subjects: Boundary conditions; Cenozoic; Cenozoic Era; Compression; Geodynamics; Lithosphere; Localization; Mathematical models; Modelling; numerical modeling; Numerical models; Numerical simulations; Plate tectonics; Plates (tectonics); Slip velocity; Statistical methods; Strain localization; strike‐slip fault; Subduction; Subduction (geology); subduction initiation; Subduction zones; Tectonics; Tectonophysics; Three dimensional models; Velocity
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2022GL102171

The recent statistics suggests that over 60% of active Cenozoic subduction initiation (SI) cases are related to the strike‐slip fault. A number of previous studies have shown that the lithospheric weak zone is a necessary condition for the SI. However, the direct effect of strike‐slip motion on lithospheric weakening and SI has rarely been investigated in numerical models due to the challenge of complex 3D boundary conditions. In this study, a new 3D model has been built with both strike‐slip and compression boundary conditions. The model results indicate that the compression at a strike‐slip boundary provides a favorable condition for the SI, with producing and maintaining a lithospheric‐scale weak zone that facilitates strain localization and SI. In addition, the high strike‐slip velocity and buoyant overriding plate contributes to the SI of young oceanic plate. This mechanism satisfies a large number of natural SI cases in the Cenozoic. Plain Language Summary Subduction zone is one of the most important elements of plate tectonics on the present Earth. How to form a new subduction zone, that is, subduction initiation (SI), is still a challenging issue in geodynamics. The lithospheric weak zone is a necessary condition for SI; otherwise, the required force for breaking the lithosphere is too high. The strike‐slip fault is a natural weak zone, and is thus a favorable place for SI. However, the strike‐slip fault is generally set as a simple weak zone in the previous models, because the strike‐slip motion itself is challenging for the numerical simulation. In this study, we have built a new 3D model with complex boundary conditions, including both strike‐slip and compression components. Based on the systematic numerical studies, we find that the compression at a strike‐slip boundary provides a favorable condition for the SI. We also find that the high strike‐slip velocity and buoyant overriding plate contributes to the SI of young oceanic plate. This mechanism satisfies and explains a large number of natural SI cases in the Cenozoic. Key Points A new 3D model has been developed with both strike‐slip and compression boundary conditions Subduction initiation (SI) prefers transpression with both compression and shear components Cenozoic SI favors strike‐slip fault with buoyant overriding plate and young subducting plate