Antarctic plate
Fifth-largest tectonic plate, moving Antarctica southward.
The Antarctic plate is one of Earth's major tectonic plates, covering roughly 60.9 million square kilometers, which makes it the fifth largest. It carries not only the Antarctic continent but also the Kerguelen Plateau and several remote islands scattered across the Southern Ocean and nearby waters. This plate originally broke away from Gondwana, the southern half of the supercontinent Pangea, and then drifted southward, carrying Antarctica to its current isolated position. That shift led to the continent’s much colder climate.
Almost all of the Antarctic plate’s boundaries are extensional mid-ocean ridges. Its neighboring plates include the Nazca, South American, African, Somali, Indo-Australian, and Pacific plates, plus the Scotia and South Sandwich plates, which meet it along a transform boundary. The plate moves at least one centimeter per year, generally toward the Atlantic Ocean. Meanwhile, the continent itself is slowly splitting apart along the West Antarctic Rift System at a rate of about one to two millimeters per year, a process that created the Transantarctic Mountains and drives all recent volcanic activity in Antarctica.
Subduction of the Antarctic plate beneath South America began about 14 million years ago, during the Miocene epoch. Initially, this subduction occurred only at the southern tip of Patagonia, with the Chile triple junction near the Strait of Magellan. As the southern Nazca plate and the Chile Rise were consumed, more northerly parts of the Antarctic plate started subducting under Patagonia, shifting the triple junction to its present location off the Taitao Peninsula at 46°15' S. This subduction is thought to have uplifted Patagonia by reducing the strong downward mantle flow that had been caused by the earlier subduction of the Nazca plate. The resulting dynamic topography raised Quaternary marine terraces and beaches along Patagonia’s Atlantic coast.
Landmasses on the Antarctic plate include Antarctica itself (divided into East Antarctica, West Antarctica, the Antarctic Peninsula, and the Transantarctic Mountains), as well as several islands: Amsterdam Island, Crozet Islands, Heard Island and McDonald Islands, Kerguelen Islands, Peter I Island, Prince Edward Islands, Saint Paul Island, South Orkney Islands, and South Shetland Islands.
- area
- 60,900,000 km² (23,500,000 sq mi)
- rank
- fifth-largest tectonic plate
- movement
- at least 1 cm per year toward the Atlantic Ocean
- rift_rate
- 1–2 mm per year along the West Antarctic Rift System
- boundaries
- extensional mid-ocean ridge systems and a transform boundary
- adjoining_plates
- Nazca, South American, African, Somali, Indo-Australian, Pacific, Scotia, and South Sandwich plates
Lore & Background
The Antarctic plate began moving the continent of Antarctica south after the breakup of Gondwana, leading to its isolated position and colder climate. It is bounded almost entirely by extensional mid-ocean ridge systems, with adjoining plates including the Nazca, South American, African, Somali, Indo-Australian, Pacific, and, across a transform boundary, the Scotia and South Sandwich plates. The plate's movement is estimated at least 1 cm per year toward the Atlantic Ocean, and the continent is splitting apart at 1–2 mm per year along the West Antarctic Rift System, responsible for the Transantarctic Mountains and recent volcanism in Antarctica.
Reader's Guide
The Antarctic plate is significant as the tectonic plate that carries the continent of Antarctica, influencing its climate and isolation. Its subduction beneath South America, which began 14 million years ago in the Miocene epoch, has uplifted Patagonia by reducing mantle down-dragging flow from the Nazca plate subduction. This dynamic topography raised Quaternary-aged marine terraces and beaches along the Atlantic coast of Patagonia. The plate's boundaries are predominantly extensional mid-ocean ridges, and its slow movement and rifting shape the Antarctic landscape, including the Transantarctic Mountains and volcanic activity. The plate's area of about 60,900,000 km² makes it the fifth-largest tectonic plate on Earth.
Did You Know?
- The Antarctic plate has an area of about 60,900,000 km², making it Earth's fifth-largest tectonic plate.
- The plate's movement is estimated at least 1 cm per year, roughly toward the Atlantic Ocean.
- The Antarctic plate started to subduct beneath South America 14 million years ago in the Miocene epoch.
- The continent is splitting apart at 1–2 mm per year along the West Antarctic Rift System.
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