Abstract:
Magnetovariational studies were carried out along four different EW profiles in Saurashtra region
in different phases, during January 2007–March 2012. Transient geomagnetic field variations (X, Y
horizontal field and Z vertical field components) recorded along these profiles are analyzed to infer the
electrical conductivity distribution of the region. The vertical field transfer functions which depict the
characteristics of electrical conductivity distribution are presented in the form of induction arrows. From
the spatial distribution of these arrows, it is inferred that the sediments filling the offshore basins have
more conductivity than those basins in Saurashtra region. Z/H pseudo sections along the four profiles in
conjunction with tectonics and other geophysical methods permit to infer that the conductivity anomaly
in the eastern part of the profiles is associated with the crustal/lithosphere thinning. The possible cause
for these anomalies may be explained in terms of partial melts associated with mafic intrusions, related
to Deccan and pre-Deccan volcanism. High resistive block related to underplating mantle material has
been reflected in 1D models of long period magnetotelluric data and its thickness reduces from west to
east. Lithosphere–asthenosphere boundary varies from 80 to 100 km.
