Miocene faulting at plate tectonic velocity in the Himalaya of central Nepal

Combination of geochemical zoning in metamorphic garnet and monazite plus in situ Th–Pb isotopic dating of monazite yields P–T conditions, ages and convergence rates for the Main Central Thrust (MCT) and affiliated faults in central Nepal. Inferred rates were 1.5±0.9 cm/yr (Langtang Thrust, ∼19 Ma), 2.2±0.7 cm/yr (Main Central Thrust, ∼15 Ma) and 7±3 cm/yr (Ramgarh Thrust, ∼10 Ma). The lower values are similar to modern convergence rates across the Himalaya, but the Ramgarh Thrust may have briefly absorbed all Indo–Asian convergence at ∼10 Ma, when foreland and marine sedimentation rates markedly increased, and at least one major strike slip fault in Tibet experienced a hiatus in movement. Variable rates of convergence across the Himalaya on Myr timescales imply Myr variations in strain rates throughout all components of the Indo–Asian orogen.