Effects of glacial isostatic adjustment since the late Pleistocene on the uplift of the Tibetan Plateau

We simulate the seven components of the geophysical signatures arising from the glacial isostatic adjustment in the Tibetan Plateau for three different ice models in order to investigate the implications for the plateau's uplift. Particular attention is devoted to the effects of the presence of asthenosphere and its uncertainty with regard to viscosity on the computational results. For this purpose, four viscosity models are constructed using newly published results concerning postglacial rebound and post-seismic deformation. For two smaller ice models, the modelled quantities are small, contributing little to the observed signals. However, for the ice model with a maximal average thickness at the last glacial maximum, the modelled quantities are pronounced in the observed signals. On the basis of the numerical results for this ice model, two main conclusions can be drawn. First, since the late Pleistocene uplift has been reduced by 10-31.4 m in the plateau and in the Himalaya mountain range, and horizontal crustal shortening has increased by 4.2-30.6 m. Second, for the present ongoing crustal motions, the uplift rates are enhanced by 1.2-3.7 mm yr(-1) in the midwest of the plateau, the subsidence rates are reduced by 1.2-3.6 mm yr(-1) in the east of the plateau, and the horizontal shortening rates are decreased by 0.6-4.2 mm yr(-1). Therefore, if the ice sheet related to the largest ice model is scientifically acceptable, the glacial isostatic adjustment is worthy of consideration as a dynamic mechanism for the uplift of the plateau since the late Pleistocene, The uncertainties in the modelled results are due to the wide range of the estimate of asthenospheric viscosity, from 10(18) to 10(20) Pa s. Any improvement made in the estimation of the asthenospheric viscosity will be beneficial to discussions about the effects of glacial isostatic adjustment on the uplift of the plateau based on the results in this paper.