Coevolution of duplexing and crustal flow during Himalayan growth

The Himalayan orogen is one of the most tectonically active regions on Earth, characterized by extensive crustal deformation due to continental collision and strong interactions between strain localization, locally high levels of erosion, and orographically enhanced precipitation. However, the relative roles of climatic, tectonic, and surface processes in driving the Himalayan growth remain controversial, with several debated models (i.e., crustal flow, out‐of‐sequence thrusting, and duplex models) existing for the Himalayan structural evolution. Here we use a coupled numerical model—integrating tectonics, orographic precipitation, and surface processes, constrained by uplift and erosion observations—to demonstrate that key geological features (including the frontal Himalayan range with outward duplexing, ductile extrusion at the plateau edge, and low-viscosity crustal flow beneath the plateau) emerge from a cyclic behavior between alternating periods of thin-skinned and thick-skinned tectonics. We also suggest that different stages in this cyclic behavior coexist along the present-day Himalayan arc and can be identified by their distinctive precipitation patterns. Our results also imply that the geometry of crustal structures is mostly controlled by the mechanical behavior of the crust and not erosion or climate.