In order to investigate the features of lithosphere and study the deformation mechanism of crust-mantle coupling in northeastern margin of Tibet plateau, we have processed the GPS data observed from 1999 to 2007, leveling data observed in 1972 similar to 2000 and relative gravity data in 1992 and 2007, we have got the horizontal velocity field, long time crustal vertical rate field and gravity variation field in northeastern margin of Qinghai-Tibet plateau. We found that the deformation style in the east is different from that in the west. In the west the crust moves toward NE and shortens mainly, but in the east it rotates clockwise mainly. As for the vertical deformation the eastern part rises with an average rate of 2.1 mm/a, the western part rises slowly with a rate less than 1.0 mm/a. The gravity in the east increases greatly with a rate of 9.0 x 10(-8) m . s(-2) . a(-1), more than that in the west with a rate of 3.1 x 10(-8) m . s(-2) . a(-1). The style of deformation variation is not gradual but occurs in a transition belt. This belt is orientated in NEE. Its north section is between Jinchan and Wuwei in Gansu province, the middle is in the east of eastern Qilian mountain and the west of Menyuan in Qinghai province, The south section is in the east of Delingha and the west of Qinghai Lake. Furthermore, by use of Precambrian tectonic framework, gravity anomaly data and seismic SKS splitting result, the lithosphere deformation mechanism is studied. We infer that the main reasons for the difference of lithosphere deformation are probably the lateral flow. of lithosphere material and the differences in lithosphere structures and crust-mantle coupling.
