The Structure of the Lithosphere and Formation Conditions of Submarine Rises in the Sub-Antarctic Sector of South Atlantic Based on Density and Physical Modeling

The complex structure of the region has been formed as a result of kinematic reorganization of plate boundaries, accompanied by the extinction of old spreading centers, the formation of new ones, and plume magmatic activity in the South Atlantic southeastern part. These processes resulted in the formation of a system of ridges, rises, and plateaus with different morphologies and geochemical characteristics. The results of density modeling of the structure of the crust and tectonosphere along the profiles, which extend from the Falkland Plateau to the Mozambique Ridge and cross a series of rises and ridges divided by deep-water basins, showed that the rises have different crustal structures indicative of their different origins. The formation conditions of various submarine rises have been studied on the basis of physical modeling. The new experimental model of the formation of the lithosphere and submarine plateaus of the region is provided, in which the important role belongs to the breakup of the Agulhas large igneous province on the Agulhas Plateau and Northeast Georgia Rise, the accretion of the oceanic crust on the Agulhas spreading ridge, and a further jump of the Agulhas spreading ridge axis leading to the termination of spreading at this ridge and the formation of a southern segment of the Mid-Atlantic Ridge and conjugated Meteor and Islas Orcadas Rises. Spreading axis jumps, which are accompanied by periodic activity of hotspots, played an important role in the formation of the submarine rises of various genetic types that, in turn, determined the different structures of their crust.