Looking beyond kinematics: 3D thermo-mechanical modelling reveals the dynamics of transform margins

Abstract. Transform margins represent ∼ 30 % of non-convergent worldwide. Their formation and evolution have traditionally been addressed through kinematic models that do not account for the mechanical behaviour lithosphere. In this study, we use high-resolution 3D numerical thermo-mechanical modelling to simulate investigate intra-continental strain localization under oblique extension. The obliquity is set velocity boundary conditions range from 15∘ (high obliquity) 75∘ (low every rheologies strong weak lower continental crust. Numerical show localized strike-slip shear zones leading transform always follows a thinning phase during which lithosphere thermally mechanically weakened. For low- (75∘) intermediate-obliquity (45∘) cases, faults are parallel extension direction but form an angle 20∘ 40∘ with plate motion vector, while higher obliquities (30∘ 15∘) develop direction. also lithosphere, stress re-orient kept constant. This evolution, due weakening leads process in three major phases: (1) initiation rigid where structures sub-perpendicular direction; (2) distributed deformation local field variations transtensional structures; (3) highly boundaries stopping deformation. Our results call thorough re-evaluation approach studying margins.