The Influence of Middle and Lower Crustal Flow on the Landscape Evolution of Orogenic Plateaus: Insights from the Himalaya and Tibet

The Tibetan Plateau serves as a model for understanding the possible influence of middle and lower crustal flow on the geomorphic and tectonic evolution of a continental plateau. Arguments are presented in favor of a weak middle (and, in some areas, lower) crust beneath the plateau, and the development of tectonic models of the Himalayan-Tibetan orogenic system that incorporate lateral flow of this weak crust under the influence of gravity are explored. Many long- and short-wavelength features of Tibetan and Himalayan landscapes are reasonably explained as a consequence of such flow.