Lithospheric models supported by the Caribbean and Levant examples help rethink transpression at plate boundaries.

Abstract

Strike-slip restraining bends, such as the Levant Fault, belonging to push-up systems and the Jamaican fault network, belonging to duplex systems, display a diversity of fault geometries and deformation patterns that reflect distinct modes of lithospheric-scale strain localization. To investigate the origin of this variability, we develop 3D numerical models of transpressional strike-slip systems using heterogeneous simple shear boundary conditions and thermally-dependent, non-linear rheology. Unlike classical analog or numerical models that impose velocity discontinuities, our approach allows spontaneous fault localization that naturally generates transpression. We systematically explore how the position and geometry of inherited weak zones influence fault development. We show that three distinct strike-slip systems emerge: (1) push-up systems with a single strike-slip fault and outward-propagating thrusts; (2) duplex systems with interacting parallel faults connected by P-shears; and (3) systems of non-interacting parallel faults. These results highlight spontaneous strike-slip localization and how initial heterogeneities control formation and evolution of long-term lithospheric deformation.