Imaging of Different Crustal and Mantle Discontinuities Below the Hyderabad Region on the Eastern Dharwar Craton

To monitor seismicity, a 10-station broadband seismic network was deployed in the Hyderabad region by CSIR-NGRI, Hyderabad, India, during 2020–2021. The analysis of radial P- receiver functions (PRFs) using data from this network detects conversions from five major crustal and mantle discontinuities below the region. Our CCP stacking of radial PRFs also images the nature and geometry of these seismic discontinuities viz., Moho (increase in positive amplitude at 30–40 km depths), Hales discontinuity (increase in positive amplitude at 90–120 km depths), lithosphere-asthenosphere boundary (LAB) (increase in negative amplitude at 130–160 km depths), 410-km (increase in positive PRF amplitude at 410–440 km depths) and 660-km (increase in positive PRF amplitude at 620–660 km depths). Our modeling also reveals that the mean depth to the Moho, Hales discontinuity (H-D) and LAB below the study region are 36, 115 and 160 km, respectively, suggesting the absence of a thick cratonic root below the EDC. We interpret the H-D boundary (at 90–125 km depths) below the Hyderabad region as a lithologic boundary between upper mantle peridotite and eclogite resulted from the Archean subduction. We also model the differential time of the 410- and 660-km conversions, which is found to be 24 s at most of the stations that is the same as the theoretical differential time between these two phases according to the IASP91 global reference velocity model, indicating a typical cratonic behaviour of the EDC. However, a noticeable upward movement of the 410-km discontinuity and a slight downward movement of the 660-km discontinuity below the central part of the study region is also modelled that suggests a thickening of the Mantle transition zone, which could be attributed to the presence of probable imprints of the Archean subduction below the Hyderabad, EDC, India.