UPLIFT RATE MEASUREMENT ACROSS HIMALAYAN FRONTAL THRUST IN MOHAND AREA

Abstract

The study aims is to reevaluate the uplift and corresponding horizontal shortening rate across the already studied section of 1-Iirna!ayan Frontal Thrust (HFT) in Mohand area. The terrace deposits across Himalayan Frontal Thrust in northwesteni part of India are fbund to be uplifted to 20 to 30 meters above modern river level. The terrace are interpreted to have been uplifted by displacement on the underlying HFT (Steven G. wesnousky, 1999). Using a simple trigonometric function Wesnousky Ct at. (1999) found? 6.9 mm/year as uplift rate. 13.8 mmlyear as fault slip rate, and 11.9 mm/year as horizontal shortening rate. As rock uplift can be measured more accurately by considering river geometly and its gradient change during the period, we measured depositional rate, sinuosity change, and its gradient along the considered river profile. Using this approach a total uplift (i.e. river incision + sinuosity change + deposition) was obtained as 29.48ni, which is larger than the previously estimated height along the abandoned terrace. Subsequently, using trigonometric method and fault bend folding model for obtaining a precise deformation rate as suggested by R.Jayagondaperumal Ct at (2013) and Lave et at (2000) respectively, yielded the corresponding horizontal shortening = 13.79 mmlyear and 15.74 mm/year. Our result shows larger value than the previously reported rate, but it is comparable with the geodetic rate. Further the shortening rates measured by these models are also compared suggesting that different models provide different rates.