Southwest Indian Ridge

The Southwest Indian Ridge is a mid-ocean ridge in the southwestern Indian Ocean, where the African and Antarctic plates move apart and new oceanic crust forms.

Seafloor spreading: The process by which magma rises at a mid-ocean ridge, forms oceanic crust, and moves older seafloor outward. Divergence across the ridge creates new crust and carries it away from the spreading axis.
African Plate: A tectonic plate that includes most of Africa and adjoining parts of the Atlantic and Indian Ocean floors. Its southern boundary with the Antarctic Plate runs along the ridge.
Atlantis Bank: A shallow, oceanic core complex on the Southwest Indian Ridge, exposing deep crustal rocks at the seafloor. It is a distinctive example of tectonic exposure of deep ridge rocks.
Oceanic core complex: A dome-shaped seafloor structure where tectonic extension exposes deep crustal or mantle rocks. Atlantis Bank belongs to this class of structures found at slow-spreading ridges.
Mid-ocean ridge: An underwater mountain chain formed where tectonic plates diverge and oceanic crust is created. The Southwest Indian Ridge is one segment of this global system.
Antarctic Plate: A tectonic plate underlying Antarctica and substantial areas of the surrounding Southern Ocean. It separates from the African Plate across the ridge.
Atlantis II Fracture Zone: A fracture zone that offsets segments of the Southwest Indian Ridge in the Indian Ocean. Its offset marks a major break in the ridge’s spreading axis.
Serpentinite: A rock formed when water chemically alters ultramafic rocks, especially mantle peridotite. Ridge faults can expose mantle rocks that react with seawater to form serpentinite.
Slow-spreading ridge: A mid-ocean ridge with a low rate of plate separation, commonly marked by deep rift valleys and rugged relief. Its slow rate of crust production helps explain the ridge’s unusually rough seafloor.
Somali Plate: A tectonic plate carrying eastern Africa and adjacent Indian Ocean seafloor, separated from the Nubian Plate by the East African Rift system. Its boundary with the Antarctic Plate connects to the ridge’s northern end.

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