Electrical architecture across the Ridge-Fault structure in the seismically active Jind-Rohtak-Delhi regions, NW India: Imaged from magnetotellurics studies

Abstract

The Delhi region is principally seismically active in the process of the India-Asia collision. Therefore, broadband Magnetotelluric (MT) studies were carried out at 11 stations along NW-SE profile passing through Jind-Rohtak regions. The rotation of the impedance tensor showed a regional strike angle of N8^oW, and phase tensor response approximate the 2-D structure. Therefore, electrical crustal structure was obtained from joint TE- and TM-modes data using a 2-D nonlinear conjugate gradient algorithm. The outcomes showed a ∼300 m thick sediments layer with conductivity ∼1 Ω-m beneath the entire profile, and conductor C2 revealed in the upper crust that joins the surface conductive layer. The conductors C1 and C3 are crustal features associated with Lahore-Delhi Ridge (LDR) and Delhi-Haridwar Ridge (DHR), respectively. The NNE-SSW trending Mahendragarh-Dehradun Fault (MDF) parallel to the DHR is suggested northwest dipping. The high conductivity supports the source of serpentine minerals in the lower crust. Our inference that the two ridges may be connected in the lower crust in the study region, and suggesting a triple junction. The fault zone tectonically associated with Himalayan arc, seismicity in the region occurs due to the movement of deep-seated heat in the process subduction. The surface conductive layer is attributed to Pleistocene age alluvium materials (silts and clays), and conductors are interpreted the partial melt or fluids that migrate upward through the pathway.