Delineation of Lithosphere Structure Variation across Eastern and Western Dharwar Craton through Joint Inversion of Receiver Function and Rayleigh Wave Group Velocity

ABSTRACT

We present a seismic image of the crust and upper mantle, obtained through joint inversion of (P-to-S) receiver functions and fundamental mode group velocity dispersion data (10-140 s) of Rayleigh waves, at nineteen broadband stations deployed along a ~650 km profile across the Eastern Dharwar Craton (EDC) to Western Dharwar Craton (WDC). Our modelling reveals that the crustal thickness varies from 34-37 to 36-42 km beneath the EDC and WDC, respectively. Moreover, a noticeable thinning (~60 km) of the lithosphere is inferred below the EDC (~140 km) compared to the WDC (~200 km). This lithospheric thickness variation is also supported by our computed average teleseismic travel-time residual variation, from +0.5 s in the EDC to -0.3 s in the WDC. We envisage that lithospheric thinning in the EDC relative to the WDC is primarily due to episodes of plume-related magmatism and mafic dike intrusions. The WDC, on the other hand, remained unaffected by such tectonic events and maintained its thicker lithospheric root.