Present-day crustal motion on the eastern Tibet Plateau and its adjacent areas

The velocity fields of the crustal motion within the Eurasia framework were measured with a precision of higher than 2 mm/yr on the basis of the Global Positioning System (GPS) measurements from 1991 to 2001 on the eastern Tibet Plateau and its adjacent areas in western China. The crustal deformation between the Indian and North China Plates is manifested in the following three parts: the Himalayas and southern part of the Plateau, central part of the Plateau (Lhasa to Golmud), and northern part of the Plateau (Golmud to Jinta), where 43 per cent, 24 per cent, and 32 per cent of the plate convergence rates are absorbed between the Indian and Eurasian plates. There exist the giant clockwisely rotated whirl structures, i.e. the (Yunnan-Tibet) whirl structures, which take the eastern Himalayan syntaxis between the Indian and South China plates as an axis. The velocities of motion for the (Yunnan-Tibet) whirl structures range between (26 to 6 mm/yr) and (24 to 7 mm/yr). Unlike the NE direction of the rotation in the central part of the Tibet Plateau, the (Yunnan-Tibet) whirl structures on the eastern Tibet Plateau, relative to Chengdu in Sichuan, are generally rotated from the northeast to the southeast and southwest. A direct genetic affiliation of the (Yunnan-Tibet) whirl structures and the eastern Himalayan syntaxis to the wedging of the (Namjagbarwa-Asarm) horn was postulated.