Abstract: The idea of ductile flow beneath the Tibetan Plateau is widely accepted. However, there is a dispute on the way and speed of the lower crustal flow. Surface motion has direct measurements such as GPS, and mantle movement has indirect methods such as S-wave splitting. As to the lower crustal movement, there is no direct observation, so that numerical analysis is very important. In this paper, we constructed a 3-D spherical viscoelastic finite element model of the Tibetan Plateau to simulate the crustal flow pattern. By fitting GPS data and comparing different models, we considered that the eastward flow of the ductile lower crust in the Tibetan Plateau has been resisted by the Sichuan Basin, a channel exists in the south-eastern corner of the plateau, and similar channels of substances do not exist on the northeast corner of the plateau. The lower crust moves several milimeter faster than the upper crust, the corresponding viscosity of the lower crust was between 10¹⁸~10¹⁹ Pa·s.

Key words: Lower crustal flow, Finite element modeling, Viscos-elastic, Tibetan Plateau