Structure and Evolution of the Northern Potwar Deformed Zone, Pakistan

Abstract

The northern Potwar deformed zone (NPDZ) is part of the active foreland fold and thrust belt of the Salt Range and Potwar Plateau in northern Pakistan. About 500 km of seismic reflection profiles are integrated with surface geologic and drilling data to examine the deformation style and structure of the NPDZ with particular emphasis on history of deformation of the Dhurnal oil field. The seismic lines suggest that the overall structure of the eastern NPDZ is a duplex structure developed beneath a passive roof thrust. The roof thrust is generated from a tipline in the Miocene Murree Formation, and the sole thrust is initiated from the same Eocambrian evaporite zone that extends 80 km southward beneath the Soan syncline and Salt Range. The Dhurnal oil field structure is a pop-up at the southern margin of the NPDZ, and developed beneath the passive roof thrust. The passive roof thrust crops out just north of Dhurnal on the steep, northern limb of the Soan syncline. An overstep passive roof thrust (Sakhwal fault) is interpreted west of Dhurnal; this fault developed due to