Tectonic evolution of the India/Eurasia collision zone

Since the collision of India with Eurasia at about 45 Ma in the mid-Eocene, roughly north-south intracontinental convergence has occurred at about 5 cma −1 . This convergence has been accommodated principally by lithospheric thickening in a widening zone between a western transpressive sinistral megashear from the Makran to Baikal and an eastern dextral megashear from Sumatra to the Tanlu Fault System. Several lines of evidence indicate that underthrusting of the Indian Shield beneath Tibet cannot account for more than a trivail portion of the convergence and numerous data sets show that lateral extrusion or escape was not a major factor in accommodating the India/Eurasia convergence. Balancing shows that there has been a maximum eastwards extrusion of the convergent zone of about 250 km, and that up to 1,000 km of shortening has occurred in the Himalayas