Abstract:We first establish two kinematic models of the Bayan Har block and inverse the slip rate of the boundary faults using a block model and GPS data. Model I includes the west segment of the East Kunlun fault and its surrounding areas, while Model Ⅱ does not include this region. The inversion results show that model Ⅱ is more consistent with the reported survey results. The differences between the two models are as follows:(1) In model Ⅱ, the extension rate is higher and strike slip rate is smaller on the southwestern section of the Altyn Tagh fault; this observation is more consistent with the regional characteristics of the area. (2) In model Ⅱ, the sinistral slip rate of the middle part of the East Kunlun fault is about 8 mm/a, which is closer to the reported results of about 10 mm/a. The slip rate is about 7 mm/a in model I. (3) Model I has a larger strike slip rate on the western segment of the East Kunlun fault; this result is not in agreement with the low seismicity and focal mechanism observed in the area. However, in model Ⅱ, the Maergaichaka fault has a high sinistral slip rate, which may be caused by the small slip rate on the Fenghuoshan fault. Hence, we omit the Fenghuoshan fault to obtain a simplified model Ⅱ and refer to it as model Ⅲ. The inversion results for model Ⅲ are more consistent with the reported results. It is known that the middle section of the East Kunlun fault and the Maergaichaka fault are not connected, but the two faults are continuous with regard to the transfer of the crustal material with the corresponding slip rates. Owing to the low slip rate of the Fenghuoshan fault on the southern boundary of the Bayan Har block, we believe that the weak material in the lower crust may have entered to part of the Bayan Har block.