Ridge torques and continental collision in the Indian-Australian plate

The excess gravitational potential energy of a collisional orogen that may be supported by focusing distributed ridge torques in a plate depends on the ratio l′ of the effective lengths of ridge systems and collisional fronts. In the Indian-Australian plate, the net torque due to the asymmetric distribution of mid-ocean ridges and young oceanic lithosphere along the southern boundary is ~8.5 × 10 ²⁵ N.m and is capable of supporting an excess potential energy of the Himalayan collision zone of up to 7.5 × 10 ¹² J/m ² . The concept that collision in the Indian-Australian plate may be sustained by ridge torques suggests that collisional driving stresses may be sensitive to l′. Changes in l′ may help explain the termination of spreading between Indian and Australia following the onset of the Himalayan collision and the early Miocene normal faulting in the high Himalaya. -from Authors