Lithospheric structure and geodynamic properties of the Tibetan plateau and its adjacent regions

Abstract

The Tibetan plateau has an elevation of 4–5 km above sea level and a crustal thickness of ∼80 km (Zhao et al., 2010d), and its ongoing tectonic evolution is one of the most important Meso-Cenozoic events affecting our planet today. The Tibetan plateau influences global climate, especially in the northern hemisphere, and the structural behavior of the crust and mantle in this region actively controls the development and evolution of the entire geodynamic regime. The Tibetan plateau was generated by continental collision and postcollisional, intra-continental deformation of the Indian and Eurasian plates beginning ∼50 Ma. Total tectonic shortening between the two plates is estimated to be at least 1 000–1 400 km, and may be as much as 2 000– 3 000 km. Although understanding the tectonic processes involved in forming the plateau has attracted the interest of geoscientists from all over the world, the mechanisms by which this shortening has been accommodated is still unknown. Over the past century, numerous models have been proposed to explain the formation and evolution of the plateau. For example, as early as the 1920s, German scientist Argand (1924) first postulated that the Tibetan plateau formed as a result of collision and post-collision convergence of the Indian subcontinent with Eurasia. This collision resulted in shortening and thickening of the crust to ∼80 km, producing the magnificent mountain ranges of the Himalaya, Karakorum, and Tianshan (Figure 1a). This perspective remains widely accepted, but the development of the plateau can also be evaluated within the context of the larger dynamic system related to subduction of oceanic lithosphere beneath eastern Eurasia and Indonesia. Willett and