Comparative Structural Analysis of the Northern Potwar Deformed Zone and the Southern Potwar Platform Zone, NW‒Himalayas, Pakistan

Abstract

Potwar Basin is one of the hydrocarbon prolific basins but pertains complex deformational style. Maximum production has been taken from Paleocene and Eocene carbonates but deeper reservoirs like Cambrian (Khewra sandstone) and Permian (Tobra formation) are also well producing. Geology of the Northern Potwar deformed zone (NPDZ) is mainly controlled by Pre-Cambrian salt, gently dipping basement and its warp. As we move towards south, salt thickness decreases near the axis of Soan syncline, north of Dhurnal structure. Eastern part of NPDZ is buried one while an emergent fold and thrust front (fault propagating fold) in the western part of NPDZ. Eastern NPDZ has duplex structure with initiation of roof thrust from the Murree Formation and sole thrust from Pre-Cambrian salt. The Southern Potwar platform zone (SPPZ) is less disturbed in comparison with NPDZ in which Pre-Cambrian salt acts as a decollement/lubricating surface over which the Cambrian to Pliocene sequence slides as a single thrust sheet. Due to the combined effect of thick overburden of ~3‒5 km and the decollement, folding and thrusting is significant in the Potwar Basin. In the eastern SPPZ, pop-up and fault propagating folds are prominent while in the western SPPZ, triangular zones, pop-up or detachment folds are significant.