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Pinjore Dun, along the piedmont zone of the Lower Siwalik hill front and within the Lower Tertiary hill range reveal the
pattern of thrust and strike-slip faulting, striking parallel to the principal structural trend (NNW-SSE) of the orogenic
belt. The active Chandigarh Fault, Pinjore Garden Fault and Barsar thrust have vertically dislocated, warped and backtilted
fluvial and alluvial-fan surfaces made up of Late Pleistocene-Holocene sediments. West- and southwest-facing
fault scarplets with heights ranging from 12 to 50 m along these faults suggest continued tectonic movement through
Late Pleistocene to recent times. Gentle warping and backtilting of the terraces on the hanging wall sides of the faults
indicate fault-bend folding. These active faults are the manifestation of north-dipping imbricated thrust faults branching
out from the major fault systems like the Main Boundary Fault (MBF) and Himalayan Frontal Fault (HFF), probably
merging down northward into a décollement. The Taksal Fault, striking NNW-SSE, shows prominent right-lateral movement
marked by lateral offset of streams and younger Quaternary terraces and occupies a narrow deep linear valley along
the fault trace. Right stepping along this fault has resulted in formation of a small pull-apart basin. Fault scarplets facing
ENE and WSW are the manifestation of dip-slip movement. This fault is an example of slip-partitioning between the
strike-slip and thrust faults, suggesting ongoing oblique convergence of the Indian plate and northward migration of a
tectonic sliver. Slip rate along the Taksal Fault has been calculated as 2.8 mm/yr. Preliminary trench investigation at the
base of the Chandigarh Fault Scarp has revealed total displacement of 3.5 m along a low angle thrust fault with variable
dip of 20° to 46° due northeast, possibly the result of one large magnitude (Mw 7) prehistoric earthquake. Taking into
consideration the height of the Pinjore surface (20 to 25 m), tentative age (8.9 ± 1.9 ka), displacement during one event
and average angle of fault dip (25°) gives slip rate of about 6.3 ± 2 mm/yr, a rate of horizontal shortening of 5.8 ± 1.8
mm/yr and recurrence of faulting of 555 ± 118 years along the Himalayan Frontal Fault.
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