KINEMATIC MODEL OF ACTIVE DEFORMATION IN CENTRAL-ASIA

The velocity field of present-day deformation in Central Asia is modelled using a set of four rotating blocks (Siberia, Tarim, Tibet, India) on a spherical earth. A best-fit is inverted on the basis of estimated shortening-rates across the main thrust zones (Himalayas, Tien Shan) and measured slip-rates along the principal strike-slip faults (Altyn Tagh and Karakorum) separating those blocks. The fit to the data implies that nearly all the present convergence between India and Asia can be accounted for by slip-partitioning on these four zones, with as much as 50% absorbed by northeastwards extrusion of Tibet. This suggests that localised deformation governs the present mechanical behaviour of the Central Asian lithosphere.