Structural Evolution of Eastern Potwar : A case study from Gujjar khan Area South East Potwar Pakistan (T-1400) (MFN 4994)

Abstract

The study area encompasses the eastern region of Potwar sub-basin which involves the adjoining areas of the Gujjar Khan and Dina, District Jhelum & Rawalpindi which lies along the western limb of the Hazara-Kashmir Syntaxis in the sub-Himalayas of Pakistan. The study area lies in the Kashmir fold-and-thrust belt which is formed during the collision of the Indian and Eurasian plates. The study deals with the structure and stratigraphy of Chattroh, Siakh, Kanger, Mandhal and areas of Districts Jhelum and Rawalpindi. The lithostratigraphic units in the study area range from Pre-cambrian Basement to Recent alluvium. The structural evaluation of surface and sub-surface of the part of eastern potwar have been carried out through integration of surface geological and sub-surface seismic data followed by construction of geoseismic cross-sections. The geoseismic cross sections reveals two level of deformation in the sub surface. The surface geologicl mapping shows series of tight folds and emergent thrusts. The Palina anticline and Bewal syncline are the folds present in the area. This is tight fold formed in the hanging wall of the Makhlot Fault. It is interpreted as hanging wall anticline. The Palina anticline is southwest vergent asymmetric open fold. The Diljabba, Tanyam and Makhlot faults are three major faults present in the study area. The Jhelum fault run very close and parallel to faults which is left lateral strike slip fault showing reverse behavior and the Diljabba, Tanyam and Makhlot Faults are reverse in nature and running almost parallel to each other. These faults are thrust and reverse in nature which are splays of main Jhelum fault which is a left lateral strike slip fault shows commonly reverse behavior at places. The area is highly imbricated. It is represented by thrusting and back thrusting in the area. The southwest directed thrust/reverse faults in the area are the imbricate splay faults of the main Jhelum fault. All of these faults are active. The sedimentary structure observed in the area is cross bedding which is used for determining the facing of the stratigraphic units. Sub surface interpretation of seismic data is done in accordance with structural geology. The structures interpreted in sub surface are Pop-up and faulted anticlines. The depositional thickness of Murree Formation in the area results in failure of (Harnoh X-01).