中文摘要：

将青藏高原及周边区域地壳分为脆性层和韧性层,并假定脆性层地壳近似弹性,韧性层为粘弹性层。利用GPS水平速度场计算地面应变场,推导地壳内部作用力在不同点产生应变率之间的关系公式。利用稳态热传导方程估算地壳内部温度场,利用破裂强度和蠕变强度相等估算脆性-韧性转换面,并进一步估算青藏高原地壳不同深度的粘滞系数分布。结果表明,青藏高原及周边区域脆性-韧性转换面一般位于中地壳,深度分布在22～37km之间,地壳较厚的区域转换层也较深;韧性层内粘滞系数分布,在中地壳约为1019～1022Pa.s,下地壳约为1017～1020Pa.s,Moho面则降至1016～1018Pa.s。

英文摘要：

Crust is divided into two layers：the elastic brittle layer and the viscoelastic ductile layer.Meanwhile,it is supposed that the elastic brittle layer approximates to elasticity,and the viscoelastic ductile layer is viscoelastic.Strain fields are calculated using GPS horizontal velocity,and a strain relation expression between two points is deduced.Meantime,interior temperature field of lithosphere is evaluated by steady heat conductive equation.Under the condition that fracture intensity is equal to creeping intensity,brittle-ductile transition plane is obtained.Varied depth effective viscosity of Tibetan plateau lithosphere are calculated.The results show that brittle-ductile transition plane generally locates in middle crust about 22~37 km depth.The thicker the crust,the deeper the transition floor.Effective viscosity of middle crust located in Tibetan plateau is between 1019~1022 Pa·s,and lower crust is between 1017~1020 Pa·s.It decreases to 1016~1018 Pa·s at Moho plane.