Journal of the Faculty of Science, Hokkaido University. Series 4, Geology and mineralogy;Vol.XXIII, No.1


A Balanced Cross-Section Across the Central Nepal Siwalik Hills; Hitauda to Amlekhganj

Schelling, Daniel;Cater, John;Seago, Rob;Ojha, T.P.

Permalink :


A balanced cross-section has been constructed across the Sub-Himalayan Siwalik Hills of the Hitauda-Amlekhganj region of central Nepal in order to determine the structural geometry of the region and to calculate tectonic shortening. The central Nepal Sub-Himalaya is underlain by a basal detachment fault, the Main Detachment Fault (MDF) which lies at a depth of about 6 km beneath the Sub-Himalaya. The Main Boundary Thrust (MBT), the Main Dun Thrust (MDT) and the Main Frontal Thrust (MFT) are all splay thrusts off of the MDF which ramp up-section through the 6 km thick Siwalik sedimentary prism with no major intervening thrust flats; the central Nepal Sub-Himalaya thus has an emergent imbricate-fan geometry. North-south shortening across the Hitauda-Amlekhganj Sub-Himalaya has been approximately 17 km, or 40% shortening. The MBT has accommodated a minimum of another 15 km of horizontal north-south shortening as well.