Propagation of Subduction Polarity Reversal Along Arc‐Continent Convergent Margin: Insights From 3D Geodynamic Simulations

Abstract Subduction polarity reversal (SPR) driven by arc‐continent collision stands as a crucial process to establish new subduction zones throughout the Phanerozoic. Despite its inherent 3D nature, investigations of SPR along extensive arc–continent collision margins have largely been confined to 2D models, providing limited perspectives on the collision‐perpendicular propagation of SPR and the associated tectonic evolution. In this study, we establish a 3D numerical model to examine the geodynamic viability and tectonic responses of SPR propagation in the context of arc‐continent collision. Through systematic parameter testing, we demonstrate that the SPR propagation can only occur when the subducting lithosphere is both thermally aged and rheologically strong. In contrast, simulations involving young or rheologically weak lithosphere result in slab tearing or slab break‐off, thereby interrupting SPR propagation. Our study offers new geodynamic insights into how the extensive Vitiaz and Andaman–Sumatra trenches were initiated and why slab tearing occurs in the Philippine and Vanuatu subduction zones.