Three-dimensional electrical imaging of the Aravali-Tural-Rajwadi geothermal system, West Coast of India

• 3D AMT/MT modeling was carried out across Aravali, Tural, and Rajawadi thermal springs located in the western part of Maharashtra, India. • The conductive zones near the surface are indicative of geothermal areas, and are linked to faults and fracture zones located within the sedimentary basin . • Apart from heat generated by radioactive elements of granitic basement, cooling and solidification of underplating materials (basaltic magma) also contributes to the heat flux in the West Coast geothermal zone (WCGZ). The West Coast geothermal system is a prominent geothermal region in the Indian subcontinent, and understanding its geothermal reservoirs is crucial for societal benefits. In the present study, we employed 3D modeling of Audio and broad-band Magnetotelluric (AMT & MT) data for the first time in the West Coast geothermal region, covering the Aravali, Tural, and Rajwadi geothermal zones, to gain insights into the evolution of geothermal zone and geothermal reservoir characteristics. The 3D inversion results revealed the presence of a thin layer of granitic crustal layer, which decreases in thickness towards the west. The rifting process along the western continental margin of India has introduced magmatism (underplated) to the crustal level, which manifests as a moderate conductivity (100–500 Ωm) layer in shallow depths (∼10 km). The cooling and solidification of underplating materials contribute to the heat flux along the West Coast geothermal zone (WCGZ). The circulation of meteoric water within the deep layers gets heated up by these mantle materials and is ejected along the fracture and fault zones that appear as hot springs. Considering a thin crustal layer, a shallow Moho, and an upwelling asthenosphere along the west coast, the WCGZ is considered a convective geothermal play type. This study enhances an understanding of the WCGZ geothermal potential and geological processes, which can have significant implications for harnessing this valuable energy resource.