Crustal structure and Moho topography of the southern part (18° S–25° S) of Central Indian Ridge using high-resolution EIGEN6C4 global gravity model data

The sophisticated tectonic setting and obscure structural heterogeneity over the Central Indian Ridge (CIR) make it a challenging target for geophysical study. The present study deals with the mapping of crustal structure over the southern part (18° S–25° S) of the CIR using EIGEN6C4 Bouguer gravity data. We have used the Radial Average Power Spectrum (RAPS) technique to estimate Moho depths and compared the results with the CRUST1.0 earth Moho model for validation purposes. We observed the RAPS using spectral window 1° × 1° exhibits a minimum root mean square (RMS) difference of 0.85 km with the CRUST1.0. Furthermore, Moho depths have also been estimated along the IFREMER cruise track (ID: 82001211; 1984) using Parker-Oldenburg’s inversion algorithm for comparison to Moho depths estimated by the RAPS. We observed that the Moho estimated from the two techniques differ with RMS value of 0.92 km. We estimate the crustal thickness over the study area by deducting water depth from the Moho depth derived using the RAPS technique. We defined thin, normal, and thick crust with thickness of 8 km. Thin crust consists of 11.03% of the total area and 9% of the total volume of the crust. Thick crust consists of 18.43% of the total area and 21.87% of the total volume of the crust. Both thin and thick crusts exhibit symmetrical and asymmetrical patterns about the CIR ridge axis. Thin crust over the study area reflects periods and locations of reduced melt supply. Thick crust arranged symmetrically about the ridge crest segments reflects periods of enhanced melt supply to the ridge axis. Thick crust located asymmetrically to the ridge axis is a product of isolated off-axis melt anomalies.