The location of compression-induced subduction initiation controlled by structural versus thermal inheritance.

Subduction initiation is a pivotal process in the Wilson cycle, yet its mechanisms remain elusive. Using 3D coupled thermo-mechanical and surface processes models, we investigated how the duration of the plate motion reversal from rifting to plate convergence and the structural versus thermal inheritance influence the location of compression-induced subduction initiation. Our results reveal that abrupt plate motion changes lead to ridge inversion-driven subduction, controlled by the inherited thermal- and melt-induced weakening. In contrast, transitions exceeding a few million years localize strain along inherited continental lithospheric-scale weak zones, enhanced by rifting-induced grain size reduction. These findings, supported by lithospheric strength and strain analysis, align with observations from inferred subduction initiation sites, such as the Algerian margin and eastern Japan Sea, highlighting the interplay between structural and thermal inheritance in controlling compression-induced subduction initiation.