Crustal structure in the Siwalik Himalayas using magnetotelluric studies

Abstract

Tectonics in the Himalayan foothills is a result of the compressional forces active since the collision between Indian and Eurasian plates and is best understood as a combination of thin skin tectonics and the basement level faulting. In order to delineate the depth extent of various thrusts and faults, wide band Magnetotelluric (MT) studies were conducted at 17 stations over the Una-Mandi profile located in the Lesser Himalayas. These studies indicate that the Palampur thrust may be a composite of two thrust zones which merge together on the south of the MT profile and extends to depths of about 8 km. The Lambagraon syncline flanked by the Sarkaghat anticline on the NE and the Bahl anticline to the SW, is about 10 km deep. The crust is underlain by a conductive layer with a resistivity of about 100 Ω − m at depth of about 50 km below the Palampur thrust and Sarkaghat anticline. This layer is delineated at shallower depths of about 35 km below the Lambagraon syncline and also on the NE towards the main boundary thrust.