We use broadband seismic data at Hyderabad to investigate average crustal properties of the central Indian shield. Crustal receiver-functions (P to SV conversions) based on data of excellent quality and azimuthal coverage show essentially no signal on the transverse component, indicating laterally homogeneous structures near this station. A joint analysis of receiver-functions and the dispersion of fundamental mode Rayleigh waves result in a simple model for the shear wave speed (V-s) with a moderate gradient of 0.010-0.028 km/sec/km in the crust. The Moho is sharp, with a contrast of approximately 0.7 km/sec in V-s across a small thickness of only 0-4 km. Measured from the middle of the Moho region, the crust is 30-34 km thick, with an average V-s of 3.58 +/- 0.10 km/sec. By modeling the timing and waveforms of Sp and SsPmp phases (SV to P conversions), we estimate the average crustal Poisson's ratio to be 0.26 +/- 0.01. This value is comparable to that found in the Tanzanian craton which is also of Archean age, both values being somewhat lower than the global average of 0.29 +/- 0.02 for shield regions that include both Proterozoic and Archean crust. A low Poisson's ratio and a slow V-s in the crust indicate that, on average, Archean crust beneath the central Indian shield is intermediate to felsic in composition, somewhat less mafic than globally averaged Precambrian crust.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below