Neotectonics Study Along The Frontal Thrust System Of The Fold-Thrust Belt Of Northwest Himalayas, Pakistan

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Developments in geodetic techniques such as Interferometric Synthetic Aperture Radar (InSAR) and the launch of new satellite missions with high spatial and temporal coverage have significantly improved our understanding of the geologic and anthropogenic processes, which include but are not limited to mapping active continental/local scale faults. This work utilizes the InSAR-SBAS (Small Baseline Subset) remote sensing technique, high-resolution digital elevation model (DEM), field data, 2D seismic and well data to constrain the structural geometry, geomorphic evolution, and active tectonic deformation of the Himalayan Frontal Thrust System. The first study focuses on the westernmost segment of the Himalayan frontal thrust in the Manzai Ranges. The geologic landscape shows active tectonic features, i.e., stream deflection, wind, and water gaps associated with geologic structures. I used the Sentinel-2B optical imagery and compiled a geologic map using band ratios. Further, the InSAR-SBAS technique was applied with geomorphic indices calculation using Sentinel-1A and TanDEM-X to analyze surface deformation. This work suggests that the frontal structures in the western Himalayas are still going through an active phase of deformation and geomorphic evolution. The second study is on the Manzai Ranges that evolved in less than 1 MA as suggested by the paleomagnetic data; however, the amount of tectonic shortening and the geomorphic evolution of the recently developed frontal structures in the Manzai Ranges are still unknown in reference to the regional Himalayan tectonics. The geometry is constrained by integrating quantitative seismic structural interpretation with field structural data and 12m resolution DEM as fault-bend and detachment folds. This work suggests a single regional detachment in the Miocene age rocks in the Manzai Ranges with no salt tectonics. In the third study, I evaluated the present-day surface deformation rate of the western Salt Range and the Trans Indus Ranges and compared their seismic versus aseismic creep related to the presence or absence of ductile detachment. I used the InSAR-SBAS technique to analyze surface deformation from 2017 – 2023. The time-series analysis shows aseismic creep of the Salt Range, Kalabagh Fault, Khisor Ranges, and the Pezu Fault due to the ductile Precambrian Salt Range Formation.

Structural Geology, Strain Partitioning, Western Himalayas, Surface Deformation, Seismic Structural Geology
Portions of this document appear in: Qureshi, K. A., and Khan, S. D. 2020. Active tectonics of the frontal Himalayas: An example from the Manzai Ranges in the recess setting, western Pakistan. Remote Sensing, 12(20), p.33-62; and in: Qureshi, K. A., Suppe, J., Khan, S. D., and Khan, Z. 2023. Structural geometry and geomorphic evolution of the Trans Indus Manzai Ranges, Western Himalayas, Pakistan. Journal of Structural Geology, 104998.