Structural Observations of the Margala Hills, Pakistan and the Nature of the Main Boundary Thrust

Abstract

The area of the Margala Hills between Islamabad in the west and Ghora Gali in the east has been investigated to reveal the structure of the tectonically important Main Boundary Thrust of the central and western Himalayas. The existence of the Main Boundary Thrust is an essential factor in the assessment of the hydrocarbon potential of the Hazara foldbelt and the adjoining Peshawar Basin.
It has been found that the basal series of the molasse sediments (Murree Formation) are at many places in normal stratigraphic contact with the underlying rocks of the mostly calcareous Indo-Pakistan Plate sediments. Within these sediments folds developed that can be followed over several tens of kilometers. The structural style including the orientation of the fold axis plane changes very rapidly along the strike. The investigation did not reveal any indication of a major thrust or fault in the area of the southern and frontal part of the Hazara foldbelt. Therefore, the existence of the Main Boundary Thrust in this area is negated.