Himalayan tectonics explained by extrusion of a low-viscosity crustal channel coupled to focused surface denudation

Recent interpretations of Himalayan-Tibetan tectonics have proposed that ch annel flow in the middle to lower crust can explain outward growth of the T ibetan plateau(1-3), and that ductile extrusion of high-grade metamorphic r ocks between coeval normal- and thrust-sense shear zones can explain exhuma tion of the Greater Himalayan sequence(4-7). Here we use coupled thermal-me chanical numerical models to show that these two processes-channel flow and ductile extrusion-may be dynamically linked through the effects of surface denudation focused at the edge of a plateau that is underlain by low-visco sity material. Our models provide an internally self-consistent explanation for many observed features of the Himalayan-Tibetan system(8-10).