GPS measurements of crustal deformation in the Baikal‐Mongolia area (1994–2002): Implications for current kinematics of Asia

Abstract

We present new geodetic results of crustal velocities over a large part of northern Asia based on GPS measurements in the Baikal rift zone and Mongolia spanning the 1994–2002 period. We combine our results with the GPS velocity field for China of Wang et al. [2001] and derive a consistent velocity field for most of Asia. We find contrasted kinematic and strain regimes in Mongolia, with northward velocities and N‐S shortening in westernmost Mongolia but eastward to southeastward motion and left‐lateral shear for central and eastern Mongolia. This eastward to southeastward motion of central and eastern Mongolia is accommodated by left‐lateral slip on the E‐W trending Tunka, Bolnay, and Gobi Altay faults (2 ± 1.2 mm yr−1, 2.6 ± 1.0 mm yr−1, and 1.2 mm yr−1, respectively) and by about 4 mm yr−1 of extension across the Baikal rift zone. Consequently, ∼15% of the India‐Eurasia convergence is accommodated north of the Tien Shan, by N‐S shortening combined with dextral shear in the Mongolian Altay and by eastward displacements along major left‐lateral strike‐slip faults in central and eastern Mongolia. We find a counterclockwise rotation of north and south China as a quasi‐rigid block around a pole north of the Stanovoy belt, which rules out the existence of an Amurian plate as previously defined and implies <2 mm yr−1 of left‐lateral slip on the Qinling Shan fault zone.