Constraints on the mantle temperature gradient along the Southeast Indian Ridge from crustal structure and isostasy: implications for the transition from an axial high to an axial valley

Axial and ridge flank depths on the Southeast Indian Ridge (SEIR) systematically increase for 2500 km from 90°E to 120°E approaching the Australian-Antarctic Discordance. The SEIR also experiences an abrupt change in ridge axis morphology near 103°30′E with axial highs found to the west and axial valleys to the east. Since the spreading rate is constant throughout this region, these variations hav...