Nature of Lithospheric Deformation Beneath the Western Continental Margin of India

The nature of lithospheric mantle deformation beneath the continental regions is a problem that has attracted global attention. It is being questioned whether the continental segments have remained the same at deeper levels since their evolution or whether recent tectonic and geodynamic events have deformed them. In the present work, we study the lithospheric thermal structure beneath the elongated, anomalous, seismically active and rifted western continental margin of India and its surroundings. Our study, based on the hitherto known evolutionary history of the Indian subcontinent, suggests that the lithospheric mantle beneath this part of the Indian peninsula has been considerably sheared, deformed and weakened due to mainly late Cretaceous - early Tertiary catastrophic and geodynamic events apart from Proterozoic thermal reactivations. Beneath this region, the asthenosphere has upwarped to a depth as shallow as 38 to 80 km due to rise of isotherms caused by subcrustal melting. Our study further reveals that the segments situated north of latitude 16° N are much warmer with shallow Moho depths than those situated south of it.