Open AccessA balanced cross-section through the eastern Nepal Siwalik hills, Bagmati river region, implications for the structure of the southern Himalaya
Author(s) -
Daniel Schelling
Publication year - 1992
Publication title -
journal of nepal geological society
Language(s) - English
Resource type - Journals
ISSN - 2676-1378
DOI - 10.3126/jngs.v8i0.32597
Subject(s) - foreland basin , geology , thrust , fault (geology) , section (typography) , thrust fault , tectonics , geomorphology , fold and thrust belt , paleontology , seismology , advertising , business , physics , thermodynamics
A balanced cross-section has been constructed across the eastern Nepal Siwalik Hills along the Bagmati River in order to determine the structural geometry of the Himalayan foreland fold- thrust belt and to estimate tectonic shortening. The Siwalik Hills are underlain by a basal detachment, the Main Detachment Fault, at a depth of about 6.9km to 8km. The Main Boundary Thrust, the Chaura- Marin Thrust and the Main Frontal Thrust are splay thrusts off the Main Detachment Fault which ramp directly up-section to the surface through 6.8 to 7.7km of Siwalik Sediments with no major intervening thrust flats; the Sub-Himalayan foreland fold thrust belt displays an emergent imbricate- fan geometry. Shortening across the Bagmati section of the Siwalik Hills has been 20km, or 40%, while thrusting along the Main Boundary Thrust has resulted in a minimum of another 25km of shortening.