The Dynamics and Surface Signal of Slab Break‐Off in Continental Settings: Insights From 3D Numerical Modeling

The fate of an oceanic plate that has been subducted over an extended period of time involves slab break‐off, which can occur either simultaneously across the entire slab or locally, creating a tear that propagates sub‐horizontally. These processes are thought to explain various geological observations, such as the evolution of foreland basins, in particular, the diachronous migration of the sedimentary facies along the orogen, the transition from under‐ to overfilled deposition, and the spatiotemporal patterns of uplift and subsidence in active orogens. These interpretations remain debated due to the non‐unique nature of geological data. To clarify the role of break‐off and tearing on the post‐collisional evolution of orogens we conducted 42 3D numerical experiments. We focus on a simplified post‐collisional setup to isolate the effects of break‐off and its lateral propagation along‐strike. We analyzed uplift and subsidence data, examining how their spatiotemporal patterns relate to the rheology of the mantle and oceanic plate. Our results indicate that high pressure dependency of the upper mantle viscosity affects the style of slab break‐off and tearing: from a scenario in which these processes yield a clear diachronous uplift to one in which these processes seem to not induce any significant surface signal. We show that the tearing velocity is correlated with the average uplift of the orogen. Models that best fit estimations of tearing velocities do not create significant surface deformation. This opens new perspectives on the relation between break‐off and tearing processes.