GPS measurements of crustal deformation in the Baikal-Mongolia
area (1994-2002): Implications for current kinematics of Asia
Calais, E., M. Vergnolle, V. Sankov, A. Lukhnev, A. Miroshnitchenko,
S. Amarjargal, and J. Deverchere, GPS measurements of crustal deformation
in the Baikal-Mongolia area (1994-2002): Implications for current kinematics
of Asia, J. Geophys. Res., Vol. 108, No. B10, 2501, doi:10.1029/ 2002JB002373,
2003.
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 NS
shortening in westernmost Mongolia but east- to southeastward motion
and left-lateral shear for central and eastern Mongolia. This east-
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, 2.6+-1.0 mm/yr, and 1.2 mm/yr, respectively) and
by about 4 mm/yr of extension across the Baikal rift zone. Consequently,
~15% of the India-Eurasia convergence is accommodated north of the Tien
Shan, by NS shortening combined with dextral shear in the Mongolian
Altay, by eastward displacements along major left-lateral strike-slip
faults in central and eastern Mongolia. We find a counter-clockwise
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 less than 2 mm/yr of left-lateral
slip on the Qinling Shan fault zone.
