Structure Formation of the Southeast Indian Ridge at the Early Stages of Development: Physical Modeling

Abstract

The authors of the article studied the features of the structure formation of the earth’s crust in the early period of the formation of the Southeast Indian Ridge, associated with the separation of Australia from Antarctica and the advancement of the rift zone to the west within the ancient oceanic lithosphere towards the large magmatic province of Kerguelen, formed by the activity of the plume of the same name. The separation of Australia and Antarctica covered a long period of continental rifting (~160‒80 Ma), which then turned into ultra-slow spreading (~80‒45 Ma), then into slow spreading (~45‒40 Ma) and then into stationary spreading at average rates (after 40 Ma). The advance of the rift zone towards the ancient oceanic lithosphere gave way to the accretion of young oceanic crust on the emerging Southeast Indian spreading ridge. The early stages of development of the young spreading ridge are captured in the modern structural plan of the study region. The advance of the rift zone from the continent into the boundaries of the ancient oceanic lithosphere led to the formation of the Naturalist Plateau and the Bruce Bank near the Antarctic margin. The split of the ancient oceanic lithosphere and the formation of a young crust on the Southeast Indian Ridge led to the formation of conjugated Diamantina and Labuan suture zones, fixing the position of the initial rift split. The transition from ultraslow spreading at the initial stage of oceanic crust formation to stationary spreading with medium velocities is clearly recorded in the change in the irregularity of the accretionary relief. The Southeast Indian Spreading Range westward collided with a large igneous province during the formation of the Kerguelen Plateau and separated the Broken Range from the plateau. The authors carried out physical modeling of the conditions for the occurrence of rifting and spreading processes, as well as structure formation in the region of the Southeast Indian Ridge.