Structural Geometry, Kinematics of Evolution, and Active Tectonics of the Frontal Himalayas in the Western Margin of the Indian Plate, Pakistan.

The Manzai Ranges at the western margin of the Indian plate in Pakistan provides a unique opportunity to study oblique margin structures related to compressional and transpressional tectonics and mechanisms of fold growth. In the present research, 2D seismic data have been integrated with surface geological and geomorphological mapping to interpret their structural geometry as fault-bend or fault propagation fold and mechanism of their fold growth as hinge migration or limb rotation in the Manzai Ranges. We also calculated the creep associated with active structures using Interferometric Synthetic Aperture Radar (InSAR) Small Baseline Subset (SBAS) analysis. The topographic expression of the Manzai Ranges is associated with the Khirgi, Jandola, and Manzai anticlines. The surface trace of the Khirgi and Jandola anticline is doubly plunging with the steeply dipping forelimb truncated by the Khirgi Thrust and the gently dipping backlimb truncated by the Jandola Thrust, respectively. Seismic data show that both the thrust faults originate from the basal detachment and cuts up-section to the surface. The surface trace of the frontal Manzai anticline is a low topographic ridge and is truncated by the blind Manzai Thrust in the seismic. The surface and subsurface seismic reveal fault-propagation fold geometry for all three anticlines. The frontal Manzai anticline supports the hinge migration as the possible kinematic fold growth model after careful selection of several geomorphic observations, i.e., wind and water gaps, streams deflection, longitudinal river profiles, and their knick points. The C-band RADAR interferometry (Sentinel-1A) showed an average uplift of 59 mm/year in the satellite line of sight (LOS) from May 2018 to October 2019. The velocity profiles show an uplift variation across the anticlines and may be related to the displacement transfer from the zone of compression in the Manzai Ranges to the zone of transpression in the PezuBhittani Ranges. This study will contribute to both structural understanding and strain accumulation due to the India-Eurasian collision in the tectonically active western margin of the Indian plate.