The exhumation detachment factory

Abstract

Abstract Rifted margins include series of tectonic structures and basement geometries that record the thinning of continental crust and the birth of oceanic spreading centers. A consensus has been reached on the fact that the evolution is composite, including a phase of basement exhumation during which detachment faults play a major role. Rolling-hinge–type models are often advocated as the driving mechanism for basement exhumation, although the structural complexity of the exhumed regions frequently prohibits detailed analysis of the ways in which the faults form and evolve through time. Here, we place constraints on this process through an analysis of continental rifting numerical simulations, which we used to map fault network activity. The high-resolution models and mapping reveal a specific weak surface where detachments initiate at depth and terminate while migrating upward to the seafloor. This “detachment factory” model provides constraints on where, when, and how detachment faults originate in an exhumation system. Our model also predicts how abandoned detachments migrate off-axis with time, within the footwall and hanging wall, generating specific signals in geophysical data sets.