Pleistocene–Holocene out-of-sequence faulting along the Medlicott-Wadia Thrust in the NW Himalaya

Understanding millennial-scale fault activity and related structural architecture from seismic gaps in active orogens is important for assessment of future seismic risks. Here, we present new Late Pleistocene–Holocene shortening rates across a segment of the 600-km-long Medlicott-Wadia Thrust (MWT) system in the Sub-Himalaya (SH) from the far-western Himalayan sector of Jammu. OSL-dated offset and folded fluvial strath terraces provide a measure for the intra-wedge convergence and document strain partitioning within the SH, among which the MWT is the most active. Estimated differential uplift rates across the frontal and rear splay of the MWT is 3.2 ± 0.8 mm/a and 3.1 ± 0.4 which translates into a cumulative Late Pleistocene–Holocene shortening rate of 5.5 ± 0.5–5.8 ± 0.5 mm/a on the MWT. Previously published balanced cross-sections proposed deformation pattern and in range of ~1 mm/a. Our study reaffirms deformation rates from neighbouring MWT fault segments; moreover, it provides independent constraints to the structural architecture of the frontal fold-and-thrust belt and implies changes in fault displacement rates on Quaternary time-scales.