TECTONIC STUDYOF NORTHERN PAKISTAN

Gravity study in the Hazara and its adjoining areas of Northern Pakistan indicated sedimentary and metasedimentary wedge in the form of Hazara-Kashmir Syntaxis (HKS) which exists on the Precambrian crystalline crust. of Indian shield. This study also indicates the presence of decollement under the western limb and absence under the eastern limb of HKS. The gravity modelling shows the crystalline crust of ۳۸ Km thick extends all the way in the Lesser and Sub-Himalaya of Northern Pakistan and occurs as faulted blocks between Hazara Lower Seismic Zone (HLSZ) and Bagh Basement Fault (BBF). The presence of decollernent under the western side of Jhelurn fault and absence under the eastern side and the collision of Indian and Eurasian plates are responsible for the formation of MS. The southward migration of sedimentary and metasedimentary wedge of the western limb of HKS developed the Jhelum fault. At present the western limb moves southward between Jhelum and Kalabagh faults. The seismicity in the area between these two faults is low due to the presence of decollement but the area is tectonically very active. The folding, faulting and landsliding along the Jhelum fault, Kalabagh fault and the Salt Range Thrust Front (SRTP) have been observed. As a result of southward movement of western limb of HKS the crackS develop in the RCC bridges constructed across the river Jhelum which is running along the Jhelum fault, The roads constructed along the river Jhelum are also damaged due to the active nature of the Jhelum fault