An early Pliocene thermal disturbance of the Main Central Thrust, central Nepal: implications for Himalayan tectonics

Since the beginning of the collision between India and Asia at about 50 Ma, the convergence in the Himalaya has largely been taken up along major thrust zones. In this study, samples of the Lesser Himalaya Formations, up to 10 km below the Main Central Thrust (MCT) and the Greater Himalaya Sequence, up to 12 km above the MCT, have been analyzed by the ⁴⁰Ar/³⁹Ar and U-Pb methods to investigate the thermal history of the MCT. Infiltration of hot fluids through the MCT zone appears to be the best hypothesis to explain the data. Simple numerical simulations, which account for heat transfer by advection within the fluid flow zone and by conduction outside it, indicate that the observed age distribution could have been produced by infiltration of hot fluids through the MCT zone at circa 5 to 4 Ma. -from Authors