Abstract: An united peneplain of Neogene period was broken up into both the surfaces of the Qinghai-Xizang(Tibet) and Yunnan plateau separated on 4500～5000m and 2000～2500m elevations after eafly Pleistocene.At the transitional zone of the block faulting between the two surfaces the landform tilting and steping down from the northwest to the southeast forms the Southeastern Margin of the Qinghal-Xizang plateau.It is also a tectonlcally active zone marked by obvious tectonomorphology,wide manifestation of hydrothermal activity and intensive seismicity.Measurement of the GPS passing through the zone in two times is undergoing extension in NW-SE.Features of the crustal and mantle structure support that the zone belongs to a boundary of thermodynamics and gravity isostatic adjustment.

Key words: Qinghai-Xizang plateau, Geodynamics, Block-faulting movement, Fault displacement rate

摘要： 统一的晚第三纪青藏高原面和云南高原面,早更新世后完全分裂解体,海拔高度分别为4500～5000m和2000～2500m.二者间的北东向块断过渡带,地形自西北向东南层层倾斜、陡降,构成青藏高原东南缘,其鲜明的构造地貌、最新断裂活动、广泛的水热显示、强烈的地震活动表明这是一条现代构造活动带。跨该带的两期GPS测量结果(1992,1994)揭示其为NW-SE向拉张性质,地壳与上地幔结构特征支持其属热动力和重力均衡调整边界。

关键词: 青藏高原, 地球动力学, 块断运动, 断层位移速率