SUNDALAND MOTION DETECTED FROM GEODYSSEA GPS MEASUREMENTS : PART II - RELATIVE MOTION OF SUNDALAND AND SOUTH CHINA BLOCKS; IMPLICATIONS ON INDIA/EURASIA COLLISION AND ON THE TECTONICS OF TAIWAN
X. LE PICHON, N. CHAMOT-ROOKE, C. VIGNY, A. WALPERSDORF, P. HUCHON AND C. RANGIN 1)
In part I, we have defined the motion of the Sundaland block with respect
to Eurasia. We compare this motion to the motion of the South China block
with respect to Eurasia as defined by Holt et al. (1995). We note that the
motion predicted by Holt et al at Shanghai is on excellent agreement with
the recent VLBI solution of Heki (1996) and that the motion predicted at
Taipei also agrees with the Geodyssea solution there. The results of local
GPS measurements at Taiwan by YU et al. (1995) confirm that Taipei belongs
to the main South China block. We then note that the pattern of motion
revealed is such that the boundaries, between India and Sundaland on the
one hand and between Tibet and South China on the other hand, are purely
transform along a N/S direction. In other words, the eastward component of
motion of the indenter is compensated by an equal eastward component of
motion of the South China and Sundaland blocks. The poles of motion are
situated in such a way that this eastward component is maximal at the
latitude of the eastern Himalayan syntaxis and decreases northward and
southward. Thus Taiwan is now situated at the latitude of maximal eastward
velocity. We discuss the geodynamic implications of these kinematics on the
tectonics of Taiwan based on the relative motion history between the
Sundaland and South China blocks along their common Red River Fault
boundary.
1) Laboratoire de Geologie,
Ecole Normale Superieure - CNRS,
Paris, FRANCE
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