Chapters authored
P-Wave Teleseismic Tomography: Evidence of Imprints of Deccan Mantle Plume below the Kachchh Rift Zone, Gujarat, India
The Indian plate had experienced the Deccan volcanism at 65 Ma when it moved over the Re-union hotspot, which has altered lithospheric structure below the Kachchh rift zone (KRZ). To quantify the influence of Deccan volcanism on the crust-mantle, the present chapter focuses on the delineation of the upper mantle structure below the KRZ, through the modeling of crust corrected P-residuals and P-wave teleseismic tomography. The crust corrected normalized P-residuals suggest dominant negative residuals associated with the central KRZ, indicating crustal and lithospheric thinning below the KRZ. A low velocity down to a depth of 170 km below the central KRZ is detected through the teleseismic tomography using these P-residuals. However, these residuals also show positive values for the surrounding un-rifted zones. Note that a low shear velocity zone extending from 100–120 km to 170–220 km depth beneath the central KRZ has already been revealed by the modeling of P-RFs. This reduction in seismic velocity in the upper mantle could be explained by the presence of trapped carbonatite/partial melts related to the Deccan volcanism. The influx of volatile CO2 emanating from the carbonatite melts in the asthenosphere might be generating lower crustal earthquakes occurring in the KRZ.
Part of the book: Forecasting Volcanic Eruptions