Structural Restoration Modeling of Fault Reactivation and Tectonic Inversion: A Case Study from the Kohat–Potwar Fold-and-Thrust Belt, Pakistan
摘要
The Kohat-Potwar fold-and-thrust belt in Pakistan extends over 250 km along the Himalayan fold-thrust system. The Potwar fold-and-thrust belt is bounded by the Main Boundary Thrust (MBT) to the north, the Kalabagh fault to the west, the Jhelum fault to the east, and the Salt Range thrust to the south. The Kohat fold-and-thrust belt, part of the sub-Himalaya in northwestern Pakistan, formed due to the Indian‒Eurasian plate collision. In our study the inverted structures in the Kohat-Potwar fold-and-thrust belt through structural restoration, were identified and analyzed. Using 2D MOVETM (2018.1) software, two seismic lines from the Potwar area and two seismic lines from the Kohat area were restored, incorporating 2D seismic data with pre-stack depth migration, subsurface geological data, and structural modeling. The analysis reveals that the Indian‒Eurasian collision caused significant uplift, driven by tectonic inversion and basement rock push, leading to back thrusts, fault-propagation folds, and pop-up structures. Seismic section restoration highlights the unfolding of the footwall block, identifying null points and revealing positive inversion during the Late Jurassic in the Potwar area and the Late Permian in the Kohat area. Reactivated normal faults from these periods were confirmed through back restoration techniques. This research enhances understanding of the tectonic processes in the region and provides a geological framework for future hydrocarbon exploration.