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<p>The western continental margin of India is a geologically complex region shaped by hotspot activity, rifting, and volcanic events. Around 65–70&#xa0;million years ago, the Reunion hotspot interacted with the Indian lithosphere, triggering extensive Deccan volcanic activity. The Saurashtra region in the northwestern Deccan Volcanic Province has undergone substantial tectonic-thermal evolution since the Mesozoic era. To investigate this evolution, a Magnetotelluric (MT) survey was conducted along the Amerili–Porbandar profile in southern Saurashtra, an area marked by volcanic plugs, dyke swarms, and fault systems. 2D modelling of MT data revealed sub-basaltic Mesozoic sediments in the central to western parts of the profile. The data indicate crustal heterogeneities, high-resistivity zones corresponding to volcanic plugs or altered Precambrian crust, and conductive anomalies found between them. Notably, two deep conductivity anomalies were identified at the base of the lower crust in the west, while moderate conductivity features in the central and eastern parts correlate with faults or fractures. Sensitivity analysis confirmed the reliability of these anomalies. The western anomalies likely reflect earlier phases of extension and rifting, later influenced by Deccan volcanism. Mid-crustal anomalies suggest pathways for magmatic intrusion through deep fractures. The interaction of the mantle plume with the crust, along with underplating and fractional crystallization, significantly altered the ancient Precambrian crust.</p>

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Magnetotelluric mapping of precambrian crust influenced by deccan volcanism in Southern Saurashtra, India

  • 期刊论文

  • 发表日期：

    2026年1月20日

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  • P. B. V. Subba Rao,
  • P. V. Vijaya Kumar

摘要

The western continental margin of India is a geologically complex region shaped by hotspot activity, rifting, and volcanic events. Around 65–70 million years ago, the Reunion hotspot interacted with the Indian lithosphere, triggering extensive Deccan volcanic activity. The Saurashtra region in the northwestern Deccan Volcanic Province has undergone substantial tectonic-thermal evolution since the Mesozoic era. To investigate this evolution, a Magnetotelluric (MT) survey was conducted along the Amerili–Porbandar profile in southern Saurashtra, an area marked by volcanic plugs, dyke swarms, and fault systems. 2D modelling of MT data revealed sub-basaltic Mesozoic sediments in the central to western parts of the profile. The data indicate crustal heterogeneities, high-resistivity zones corresponding to volcanic plugs or altered Precambrian crust, and conductive anomalies found between them. Notably, two deep conductivity anomalies were identified at the base of the lower crust in the west, while moderate conductivity features in the central and eastern parts correlate with faults or fractures. Sensitivity analysis confirmed the reliability of these anomalies. The western anomalies likely reflect earlier phases of extension and rifting, later influenced by Deccan volcanism. Mid-crustal anomalies suggest pathways for magmatic intrusion through deep fractures. The interaction of the mantle plume with the crust, along with underplating and fractional crystallization, significantly altered the ancient Precambrian crust.