Detailed Shear-Wave Velocity Modeling Beneath Cuddapah Basin, India

Paswan, Abhilash Kumar (2016) Detailed Shear-Wave Velocity Modeling Beneath Cuddapah Basin, India. Masters thesis, Indian Institute of Science Education and Research Kolkata.

PDF (MS dissertation of Abhilash Kumar Paswan (11MS052)) Abhilash_Kumar_Paswan-11MS052.pdf - Submitted Version Restricted to Repository staff only Download (4MB)

Abstract

Knowledge of the composition and thickness are two critical parameters to understand the origin and evolution of the continental crust. Most of the geophysical studies over south India are focused mostly on Dharwar Craton and very small amount on the Cuddapah Basin. In the present study an attempt have been made to evaluate those parameters beneath Cuddapah Basin, a crescent shaped structure, which has been believed to be one of the largest intra-cratonic Proterozoic sedimentary basins of India situated in the eastern part of the Dharwar Craton of the south Indian shield. Receiver function, a well known seismological technique used to find the crust and upper mantle structure, have been calculated from teleseismic earthquakes recorded over 11 seismic stations in the Cuddaph Basin, and are modeled using a global optimization technique known as Neighbourhood Algorithm (NA) followed by joint inversion. Results have been also compared with H-Vp/Vs method. The results show, crustal thickness variation from 32-40 km (with average of 36 km) and average Vs ∼3.55 km/s beneath the study area. It is found that Moho is deeper below the two faults Gudur-Cuddapah and the Veldurti-Kalva-Gani fault system, which separates Cudaapah basin into three different blocks. It is seen that crust is going thicker towards the east along the profile from west to east. The overall crustal composition varies from intermediate to mafic (Vp/Vs ∼1.75-1.83). Average Vs of upper, middle and lower crust varies ∼3.45, ∼3.65, 3.7-3.9 km/s, respectively, while high Vp/Vs (∼1.8) are observed all over the crust corresponds to mafic crust beneath most part of study area. Our results also suggests the presence of Moho offset ~6km in the eastern part of the basin.

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