Pacific–Antarctic Ridge

The Pacific–Antarctic Ridge is a mid-ocean ridge marking the divergent boundary between the Pacific Plate and Antarctic Plate, where seafloor spreads as magma rises and cools.

Seafloor spreading: The process by which new oceanic crust forms at a ridge and moves away on opposing tectonic plates. At this ridge, spreading separates the Pacific and Antarctic plates and creates new seafloor.
Pacific Plate: A major tectonic plate underlying most of the Pacific Ocean basin. Its southern boundary with the Antarctic Plate is the Pacific–Antarctic Ridge.
East Pacific Rise: A fast-spreading mid-ocean ridge extending through the eastern Pacific Ocean. It is a neighboring ridge system with a substantially faster spreading regime.
Plate reconstruction: A scientific model of past tectonic plate positions and motions through geological time. Magnetic and fracture-zone patterns along the ridge help constrain Pacific–Antarctic motion.
Magma supply at mid-ocean ridges: The delivery and storage of melt beneath spreading centers that builds oceanic crust. Variations in melt supply help explain differences in crust and volcanic structure along the ridge.
Magma: Molten or partially molten rock beneath Earth's surface. Magma rises beneath the ridge and supplies much of the crust formed there.
Antarctic Plate: A tectonic plate underlying Antarctica and much of the surrounding Southern Ocean. Its northern boundary against the Pacific Plate follows this ridge.
Chile Rise: A spreading ridge in the southeastern Pacific that approaches the Chile margin. Its subduction beneath South America has carried ridge segments toward the Pacific–Antarctic system.
Geomagnetic reversal: A change in Earth's magnetic field direction that reverses the polarity recorded in rocks. Reversals create magnetic stripe patterns used to date and measure seafloor spreading.
Oceanic core complex: A domed seafloor exposure of deep crust or mantle formed through detachment faulting at a ridge. Such structures can reveal tectonic extension where magma does not fill the spreading gap.

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South Pacific OceanRelated: This spreading ridge forms part of the South Pacific seafloor.