Gravity patterns and crustal architecture of the South-Central Indian Ridge at 22-17S: Evidence for the asymmetric ridge accretion

The present study examines the gravity-derived structural fabric and crustal structure beneath the southern portion of the Central Indian Ridge at 22 degrees-17 degrees S. We examined the structures using enhanced edge detection techniques like gradient amplitude of the vertical derivative (HGVD), improved horizontal tilt angle (ITDX), gradient amplitude of the NTilt (HGNTilt) and the fast sigmoid function (FSED) on synthetic examples and the gravity data of the study region. The gravity-derived lineaments describes the lineaments that are parallel to fracture zones trending in ENE-WSW, parallel to segments/major ridge axis, near circular lineaments probably depicting ascending magma sources. We estimated the depth to the gravity-derived lineaments using the tilt_depth technique, which reveals the presence of lineaments with shallow source depth range at 2.5-7 km. The south-Central Indian Ridge is characterized by numerous lineaments with random depths that shows variable spreading rates and continuous ridge jumps. The major lineament depths are rooted into the lower crust beneath the major axis and the upper mantle in the region away from it. In addition, gravity inversion of low-pass filtered Bouguer anomaly data is used to estimate the crustal thickness. The gravity inversion shows that the Moho depth varies from 5 to 14.5 km, which shows thicker crust along the principal ridge axis and thinner in the surrounding regions. The structural fabric in combination with the crustal thickness, depth of the lineaments, age of the ridge crust, earthquake data suggests discrete minor/local ridge jumps along the major ridge axis and asymmetric accretion along the ridge axis.