D K Tyagi
Articles written in Journal of Earth System Science
Volume 117 Issue 3 June 2008 pp 189-200
Magnetotelluric investigations have been carried out in the Garhwal Himalayan corridor to delineate the electrical structure of the crust along a proﬁle extending from Indo-Gangetic Plain to Higher Himalayan region in Uttarakhand,India.The proﬁle passing through major Himalayan thrusts:Himalayan Frontal Thrust (HFF),Main Boundary Thrust (MBT)and Main Central Thrust (MCT),is nearly perpendicular to the regional geological strike.Data processing and impedance analysis indicate that out of 44 stations MT data recorded,only 27 stations data show in general,the validity of 2D assumption.The average geoelectric strike, N70°W, was estimated for the proﬁle using tensor decomposition.2D smooth geoelectrical model has been presented,which provides the electrical image of the shallow and deeper crustal structure.The major features of the model are (i)a low resistivity (> 50𝛺 m),shallow feature interpreted as sediments of Siwalik and Indo-Gangetic Plain,(ii)highly resistive (< 1000 𝛺m)zone below the sediments at a depth of 6 km,interpreted as the top surface of the Indian plate,(iii)a low resistivity (> 10𝛺 m) below the depth of 6 km near MCT zone coincides with the intense micro-seismic activity in the region. The zone is interpreted as the partial melting or ﬂuid phase at mid crustal depth.Sensitivity test indicates that the major features of the geoelectrical model are relevant and desired by the MT data.
Volume 128 | Issue 8
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