India-Asia Collision and the Uplift of the Tibetan Plateau

The processes of the India-Asia continental collision, and the uplift and growth of the Tibetan Plateau are discussed in this chapter. The closure of the Neo-Tethyan ocean and the India-Asia collision are the prerequisite and basis for the formation of the Tibetan Plateau. Based on various lines of evidence, the initial India-Asia collision took place at 65 ± 5 Ma with the main phase of collision at ~45 ± 5 Ma, and then followed by post-collisional processes. The main phase of the collision is characterized by the emplacement of the volumetrically significant Gangdese batholith and widespread of high temperature volcanic eruptions with asthenospheric mantle material contribution. The India-Asia collision and the continued convergence gave long-term effects on the Plateau. The formation of the extremely thickened Tibetan crust is closely related to the India-Asia collision by means of combined contributions of asthenospheric mantle materials and tectonic compression. The collisional and post-collisional igneous rocks in the Tibetan Plateau show significant mantle contributions. It is proved that two types of continental crust coexist in the Tibetan Plateau, the juvenile crust and reworked mature crust. The crust of the northern and southern Lhasa subterranes is dominated by juvenile crust, while the crust of the central Lhasa subterrane is dominated by reworked mature crust. Syncollisional felsic magmatism may in fact account for much of the net contribution to continental crust growth. At least 1400 km of north-south shortening has been absorbed since the onset of the India-Asian collision. The surface uplift history of the Tibetan Plateau and Himalaya is among the most important topics in geosciences because of its effects on regional and global climate variation since the Cenozoic, monsoon intensity, regional vegetation ecological models, biodiversity and watershed models. In general, there are three general views on the pattern and mechanism of uplift and growth of the Plateau: (1) crustal and lithospheric shortening, thickening and convective instability caused uplift of the plateau and growth of the plateau from south to center and then to north; (2) the oblique collision between the Indian plate and the Eurasian plate caused successive uplift and growth from south to north; (3) the uplift of the Plateau started in pre-Eocene time from the Lhasa and Qiangtang terranes and expanded stepwise throughout the Neogene toward its present southern and northern margins by multiple driving forces. There have been six accelerated periods of uplift of the Tibetan Plateau since the Miocene, i.e., 25–20 Ma, 16–14 Ma, 10–7 Ma, 4.5–2.6 Ma, 1.6–1.0 Ma and 0.7 Ma, which well correspond to the key episodes of Asian monsoon and aridity evolution.