GPS measurements of crustal deformation in the Baikal-Mongolia area (1994-2002) : Implications for current kinematics of Asia
Résumé
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 À1 , 2.6 ± 1.0 mm yr À1 , and 1.2 mm yr À1 , respectively) and by about 4 mm yr À1 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 À1 of left-lateral slip on the Qinling Shan fault zone.
Domaines
Planète et Univers [physics]
Origine : Fichiers éditeurs autorisés sur une archive ouverte