Superficial viscosity of liquids

Abstract

Long-standing problems in the geological evolution of the Tibetan–Himalayan orogen include where the India–Asia convergence was accommodated and how the plateau grew. To clarify these problems, we review the deformations and their role in the plateau's growth. Our results show that ~ 1630 km of shortening occurred across the Tibetan–Himalayan orogen since ~ 55 Ma, with more than ~ 1400 km accommodated by large-scale thrust belts. These thrust belts display an outward expansion from central Tibet and couple with the surficial uplift. The development of the Tibetan plateau involved three significant steps: Primitive plateau (~ 90–55 Ma), Proto-plateau (~ 55–40 Ma), and Neoteric plateau (~ 40–0 Ma). Several processes have collaborated to produce the Proto-plateau, including the pre-existing Primitive plateau, the India–Asia collision, and subductions of Greater India and Songpan–Ganzi beneath the Lhasa–Qiangtang terrane. Since ~ 40 Ma, the Proto-plateau, which was dominated by a topographic gradient, lower crustal flow and continuous India–Asia convergence, experienced three periods of rapid outward growth (~ 40–23, ~ 23–10, and ~ 10–0 Ma) in general. The N–S trending rifts were caused by the eastward growth of the plateau dominated by thrusting and crust flow in central Tibet, while they were the results of intense N–S shortening in Himalaya.