Structural evolution and sequence of thrusting in the High Himalayan, Tibetan—Tethys and Indus suture zones of Zanskar and Ladakh, Western Himalaya

The timing of motion on major thrusts in the Western Himalaya shows an extremely complex sequence that spans approximately 70 Ma from the latest Cretaceous throughout the Tertiary. Three major phases of thrusting can be distinguished. The earliest phase (T1) is associated with emplacement of Tethyan basin thrust sheets (Lamayuru sediments and Spontang ophiolite) south and south-westwards onto the submerged northern passive margin of India (75-60 Ma). Collision between India and Asia occurred at 50-36 Ma and was followed immediately by the major phase (T2) of crustal shortening involving large-scale south and south-westward directed thrusting of the complete Palaeozoic, Mesozoic and Late Tertiary Tibetan—Tethys zone rocks. Preliminary balanced cross-sections show a minimum shortening of 126 km of these rocks across the Zanskar Range. The late collision phase (T3) involved re-thrusting of the previously stacked pile (breaching or leap-frog thrusting) reversing the earlier stacking order in places, and widespread steepening, overturning and backthrusting along the whole northern margin of the Tibetan—Tethys zone and throughout the Indus suture zone.