Electrical signatures of the Earth’s crust in central India as inferred from magnetotelluric study

G Dhanunjaya Naidu,T Harinarayana,K Veeraswamy

doi:10.5047/eps.2011.08.004

G Dhanunjaya Naidu, T Harinarayana + Show 1 more

Open Access

https://doi.org/10.5047/eps.2011.08.004

Copy DOI

Abstract

The tectonic scenario of the Narmada-Son Lineament (NSL) zone has been the subject of debate for the last few decades. It is characterized tectonically as a highly-disturbed zone in Indian geology since Precambrian times. A magnetotelluric (MT) study has been carried out across the NSL zone along a 270-km-long N-S-trending traverse, extending from Hoshangabad in the North to Ner in the South. As a part of the present study, 25 magnetotelluric soundings have been collected and the data rotated to N70°E after removing local distortions, arising from 3D galvanic effects, using the Groom-Bailey decomposition technique. 2-D inversion has been carried out using an NLCG scheme. The results derived from the 2-D inversion have brought out the highly conductive nature of the mid-lower crust at places coinciding with the known faults. The significant high heat flow and seismicity in the region associated with these faults may be caused by tectonic activity and the highly conductive nature of the mid-lower crust. This may be due to the partial melting of subsurface rocks resulting from the high temperature caused by mantle upwarping in the region. The results are also compared with the gravity and a nearby Deep Seismic Sounding (DSS).

Highlights

The Narmada-Son Lineament (NSL) is a late Archean mega geo-fracture extending for about 1200 km across the Indian peninsula in the E-W/ENE-WSW direction
A major contribution from the present study is to understand the nature of the crust and mantle structure more clearly and to examine the electrical signatures of the surface mapped faults such as the Narmada South Fault (NSF), Tapti Fault (TF), Gavligarh Fault (GF) and Purna Fault (PF), etc
Anomalous conductive features associated with significant seismicity is not discussed in detail in the previous studies

Summary

Introduction

The Narmada-Son Lineament (NSL) is a late Archean mega geo-fracture extending for about 1200 km across the Indian peninsula in the E-W/ENE-WSW direction. This lineament is highly disturbed and reactivation of this lineament is believed to be due to the collision of the Indian plate with the Eurasian plate. This lineament is shown to be situated close to the zones of fractures belonging to early Precambrian, Cretaceous and post-Deccan trap period. A major contribution from the present study is to understand the nature of the crust and mantle structure more clearly and to examine the electrical signatures of the surface mapped faults such as the Narmada South Fault (NSF), Tapti Fault (TF), Gavligarh Fault (GF) and Purna Fault (PF), etc.

Data Analysis The MT data were collected using an ADU-06

Discussion and Conclusions