Early–Middle Eocene Exhumation of the Trans-Himalayan Ladakh Batholith, and the India–Asia Convergence

Very fast Early–Middle Eocene exhumation of theTrans-Himalayan Ladakh Batholith (LB) is revealedby new Rb–Sr biotite and zircon fission-track agesalong with the already published ages on these minerals.Exhumation peaked at 3.5 ± 0.9 mm/a between50–45 Ma (⁴⁰Ar/³⁹Ar hornblende ages) and 48–45 Ma(Rb–Sr biotite ages) as a consequence of the India–Asia convergence. It was followed by deceleration at arate of 1.2 ± 0.2 mm/a until 43–42 Ma (zircon FT ages),like the Deosai batholith in the west. Exhumationrates finally decreased during Oligocene to a minimumof ~0.1 mm/a before a mild late Miocene–Holocene acceleration. Lower-Middle Eocene exhumationof the LB was tectonically controlled by slabbreak-off of the Neo-Tethys oceanic lithosphere and underthrusting of the Himalayan Metamorphic Belt.