Evolution of the Trans-Himalayan Ladakh Arc, Geochemical and Geochronological Constraints

The Indus-Tsangpo Suture zone (ITSZ) is considered the collision zone between the Indian and Eurasian plates. Most workers suggest the Himalayan collision occurred between 50 Ma and 45 Ma. New U-Pb zircon data indicate that this switch occurred between 31 Ma and 18 Ma. The collision might be a series of collisionaccretion events from 70 Ma to 30 Ma. The upright folding took place at a later time, i.e. mid-Miocene or younger. We also present Argon Isotope data on erosion from the Ladakh Batholith. U-Pb data on detrital zircon from the Karakorum Range indicates presence of Gondwanic elements considerably north of the Himalayas. These data open a new debate: Where does India end and Eurasia begin