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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. [ABSTRACT FROM AUTHOR]

Two end‐member kinematic models of crustal shortening across the Himalaya are still debated: one assumes localized thrusting along a single major thrust fault, the Main Himalayan Thrust (MHT) with non-uniform underplating due to duplexing, and the second one advocates for out‐of‐sequence thrusting in addition to thrusting along the MHT and under-plating. Furthermore, several studies argue that all crustal shorting during the Quaternary is accommodated within Sub-Himalayan fold and thrust belt. In this study, we combined tectonogeomorphic field observations, topographic analysis and luminescence dating of the Quaternary alluvium from the Kishtwar region in NW Himalaya. We have used 30m SRTM data to analyze the regional geomorphic parameters of the area and found that the river Chenab shows, as previously reported, significant changes in the longitudinal river profile, hypsometric integral, valley width and normalized steepness indices across the Kishtwar window situated ~ 150 km inside the Himalayan front. Unadjusted hypsometry, high ksn values, and several non-lithological knickpoint zones in the Chenab river profile hints towards possible ongoing neotectonic activity especially at the western margin of the window. We combined our morphometric analysis with field observation and field data on rock strength and observed tilted Quaternary deposits along the Chenab valley. We have observed faults disrupting Quaternary fluvial sequences and ~20֯ NE-tilted fluvial sequence of pebble conglomerate and coarse sand layers in the vicinity the town of Kishtwar. Even, the observed knickpoints within the window do not correspond to significant changes in the substrate rock strength and therefore hint about their non-lithologic origin. We also observed changes in the drainage pattern of Chenab, as it was frequented by large landslides (despite being located in a fairly-low rainfall region) and landslide-dammed lakes throughout the Kishtwar window and downstream. Previously published young (<3 Ma) apatite fission track ages from the Lesser Himalayan duplex in the Kishtwar Window suggest higher exhumation over million-year timescale. Therefore, our findings possibly hint towards a protracted tectonic uplift process – and the quaternary tilted deposits suggests that this deformation is active until today or very recent. Moreover, frequent low-magnitude mid-crustal (8-30 km) seismic events, steep channel gradients, high angle bedrock foliations of the Lesser Himalayan duplex, multiple knickpoints and young AFT ages within the Kishtwar window hints about active shortening accommodated due to movement along a mid-crustal ramp of the MHT.We are processing the OSL samples obtained from the deformed sand and silt layers within the alluvium. We are hopeful that we will be able to chronologically constrain the late Quaternary deformation with the new luminescence ages. [ABSTRACT FROM AUTHOR]