Tectonics of the Hazara and Adjoining Areas, Based on Gravity Data, Northwest Himalaya, Pakistan

Abstract

Gravity data in the Hazara-Kashmir Syntaxis of northern Pakistan has been incorporated into interpretation of the gross crustal structure of the area. In this area, due to the continued northward migration of Indian plate, the Indian plate has been overridden by slices of its own northern margin and activity has caused the slight thickening of crust in the northeast and northwest of the Hazara-Kashmir Syntaxis. In the sedimentary wedge, the thin-skin structures have been developed by the southward migration of the sedimentary wedge. In northern Pakistan, Late Precambrian to Early Cambrian strata constitutes the zone of decollement. It is absent in eastern side in Kashmir and India. In the eastern limb of the Hazara-Kashmir Syntaxis, the Main Boundary Thurst (MBT) and the Panjal Thrust (PT) are developed. Here the strong coupling between sediments and basement occurred due to the absence of decollement which caused the high topography of the Hazara-Kashmir Syntaxis range front. In the western limb the MBT and the Nathiagali Thrust (NT) are developed. These thrust sheets moved southward over this decollement. The thrust system of eastern and western limbs is converging near the apex of Hazara-Kashmir Syntaxis. The differential movement resulted due to presence and absence of salt in the area developed the Jhelum fault. Jhelum fault cuts the PT, MBT and the Kashmir Boundary Thrust (KBT) in the Kashmir side and the MBT and MT in the western side in northern Pakistan. The sedimentary wedge of the western limb of the Hazara-Kashmir Syntaxis moves southward along this fault.