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

Abstract

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.