Transient Electromagnetic Investigations in a Tectonic Domain of the Kachchh Intraplate Region, Western India: A Morphotectonic Study of the Kachchh Mainland Fault

The Kachchh Mainland Fault (KMF) in the central position of the Kachchh paleo rift basin of the northwestern India is the main fault system where the reverse movement started along preexisting normal fault planes during postrift tectonic inversion at end of the Tertiary period. We present the analyses of transient electromagnetic data at 68 sites, distributed along nine traverses across the KMF zone within the Kachchh Mainland. The resistivity sections across the KMF zone do not only image the shallow subsurface geometry of the fault but also delineated synthetic and antithetic splays of the primary faults. An experimentally estimated scaling factor from the late-time TEM response, which is a proxy for fracture density of the geological formation, is well coincides with the fault zones that are delineated in the present study. The subsurface resistivity structure infers in general north-dipping reverse faulting along the various segments of the KMF. Some of the en echelon splays form flower structure scenario, suggesting either presence of localized preserved transtensional features in this regional compressive regime or a combination of both positive and negative flower structure scenarios. The observed anomalous deep conducive zones in the fault zone could qualitatively suggest neotectonic activity in the region. The study supports the presence of oblique to transverse faults that bisects the primary KMF. We opined that these transverse structures along with the splays could play a key role in transferring part of stress that being accumulating in the KMF zone.

Geoelectric resistivity section across a profile P4 together with topography

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