Antarctic Plate

The Antarctic Plate is a tectonic plate containing the continent of Antarctica, the Kerguelen Plateau and extending outward under the surrounding oceans. After breakup from Gondwana (the southern part of the supercontinent Pangea), the Antarctic plate began moving the continent of Antarctica south to its present isolated location causing the continent to develop a much colder climate.[2] The Antarctic Plate is bounded almost entirely by extensional mid-ocean ridge systems. The adjoining plates are the Nazca Plate, the South American Plate, the African Plate, the Somali Plate, the Indo-Australian Plate, the Pacific Plate, and, across a transform boundary, the Scotia Plate.

The Antarctic Plate has an area of about 60,900,000 km2 (23,500,000 sq mi).[3] It is the Earth's fifth-largest plate.

The Antarctic Plate's movement is estimated to be at least 1 cm (0.4 in) per year towards the Atlantic Ocean [4]

Antarctic Plate
The Antarctic Plate
TypeMajor
Approximate area60,900,000 km2 (23,500,000 sq mi)[1]
Movement1north-west
Speed112–14 mm (0.47–0.55 in)/year
FeaturesAntarctica, Southern Ocean
1Relative to the African Plate

Subduction beneath South America

The Antarctic Plate started to subduct beneath South America 14 million years ago in the Miocene epoch. At first it subducted only in the southernmost tip of Patagonia, meaning that the Chile Triple Junction lay near the Strait of Magellan. As the southern part of the Nazca Plate and the Chile Rise became consumed by subduction the more northerly regions of the Antarctic Plate began to subduct beneath Patagonia so that the Chile Triple Junction lies at present in front of Taitao Peninsula at 46°15' S.[5][6] The subduction of the Antarctic Plate beneath South America is held to have uplifted Patagonia as it reduced the previously vigorous down-dragging flow in the Earth's mantle caused by the subduction of the Nazca Plate beneath Patagonia. The dynamic topography caused by this uplift raised Quaternary-aged marine terraces and beaches across the Atlantic coast of Patagonia.[6]

Lands

References

  1. ^ "Sizes of Tectonic or Lithospheric Plates". Geology.about.com. March 5, 2014. Retrieved January 22, 2016.
  2. ^ Fitzgerald, Paul (2002). "Tectonics and landscape evolution of the Antarctic plate since the breakup of Gondwana, with an emphasis on the West Antarctic Rift System and the Transantarctic Mountains" (PDF). Royal Society of New Zealand Bulletin (35): 453–469. Retrieved February 1, 2015.
  3. ^ Wohletz, K.H.; Brown, W.K. "SFT and the Earth's Tectonic Plates". Los Alamos National Laboratory. Archived from the original on February 17, 2013.
  4. ^ Jiang, Wei-Ping; E, Dong-Chen; Zhan, Bi-Wei; Liu, You-Wen (2009). "New Model of Antarctic Plate Motion and Its Analysis". Chinese Journal of Geophysics. 52 (1): 23–32. doi:10.1002/cjg2.1323. ISSN 2326-0440.
  5. ^ Cande, S.C.; Leslie, R.B. (1986). "Late Cenozoic Tectonics of the Southern Chile Trench". Journal of Geophysical Research-Solid Earth and Planets. 91: 471–496. doi:10.1029/JB091iB01p00471.
  6. ^ a b Pedoja, Kevin; Regard, Vincent; Husson, Laurent; Martinod, Joseph; Guillaume, Benjamin; Fucks, Enrique; Iglesias, Maximiliano; Weill, Pierre (2011). "Uplift of quaternary shorelines in eastern Patagonia: Darwin revisited" (PDF). Geomorphology. 127 (3–4): 121–142. doi:10.1016/j.geomorph.2010.08.003.
Andean Volcanic Belt

The Andean Volcanic Belt is a major volcanic belt along the Andean cordillera in Argentina, Bolivia, Chile, Colombia, Ecuador, and Peru. It is formed as a result of subduction of the Nazca Plate and Antarctic Plate underneath the South American Plate. The belt is subdivided into four main volcanic zones that are separated from each other by volcanic gaps. The volcanoes of the belt are diverse in terms of activity style, products, and morphology. While some differences can be explained by which volcanic zone a volcano belongs to, there are significant differences within volcanic zones and even between neighboring volcanoes. Despite being a type location for calc-alkalic and subduction volcanism, the Andean Volcanic Belt has a broad range of volcano-tectonic settings, as it is a rift systems and extensional zones, transpressional faults, subduction of mid-ocean ridges and seamount chains apart from a large range on crustal thicknesses and magma ascent paths, and different amount of crustal assimilations.

Romeral in Colombia is the northernmost active member of the Andean Volcanic Belt. South of latitude 49° S within the Austral Volcanic Zone volcanic activity decreases with the southernmost volcano Fueguino in Tierra del Fuego archipelago.

Antarctic

The Antarctic (US English , UK English or and or ) is a polar region around the Earth's South Pole, opposite the Arctic region around the North Pole. The Antarctic comprises the continent of Antarctica, the Kerguelen Plateau and other island territories located on the Antarctic Plate or south of the Antarctic Convergence. The Antarctic region includes the ice shelves, waters, and all the island territories in the Southern Ocean situated south of the Antarctic Convergence, a zone approximately 32 to 48 km (20 to 30 mi) wide varying in latitude seasonally. The region covers some 20 percent of the Southern Hemisphere, of which 5.5 percent (14 million km2) is the surface area of the Antarctic continent itself. All of the land and ice shelves south of 60°S latitude are administered under the Antarctic Treaty System. Biogeographically, the Antarctic ecozone is one of eight ecozones of the Earth's land surface.

Bellingshausen Plate

The Bellingshausen Plate was an ancient tectonic plate that fused onto the Antarctic Plate. It is named after Fabian Gottlieb von Bellingshausen, the Russian discoverer of Antarctica.

The plate was in existence during the Late Cretaceous epoch and Paleogene period adjacent to eastern Marie Byrd Land. Independent plate motion ceased at 61 mya. The boundaries are poorly defined.

Bouvet Triple Junction

The Bouvet Triple Junction is a geologic triple junction of three tectonic plates located on the seafloor of the South Atlantic Ocean. It is named after Bouvet Island, which lies 275 kilometers to the east. The three plates which meet here are the South American Plate, the African Plate, and the Antarctic Plate. The Bouvet Triple Junction is an R-R-R type, that is, the three plate boundaries which meet here are mid-ocean ridges: the Mid-Atlantic Ridge (MAR), the Southwest Indian Ridge (SWIR), and the South American-Antarctic Ridge (SAAR).

Chile Triple Junction

The Chile Triple Junction (or Chile Margin Triple Junction) is a geologic triple junction located on the seafloor of the Pacific Ocean off Taitao and Tres Montes Peninsula on the southern coast of Chile. Here three tectonic plates meet: the South American Plate, the Nazca Plate, and the Antarctic Plate. This triple junction is unusual in that it consists of a mid-oceanic ridge, the Chile Rise, being subducted under the South American Plate at the Peru–Chile Trench.

The Antarctic Plate started to subduct beneath South America 14 million years ago in the Miocene epoch forming the Chile Triple Junction. At first the Antarctic Plate subducted only in the southernmost tip of Patagonia, meaning that the Chile Triple Junction lay near the Strait of Magellan. As the southern part of Nazca Plate and the Chile Rise became consumed by subduction the more northerly regions of the Antarctic Plate begun to subduct beneath Patagonia so that the Chile Triple Junction advanced gradually to its present position in front of Taitao Peninsula at 46°15’.Taitao Peninsula lies near the triple junction and various geological features, such as the Taitao ophiolite, are related to the dynamics of the triple junction.

East Pacific Rise

The East Pacific Rise is a mid-oceanic ridge, a divergent tectonic plate boundary located along the floor of the Pacific Ocean. It separates the Pacific Plate to the west from (north to south) the North American Plate, the Rivera Plate, the Cocos Plate, the Nazca Plate, and the Antarctic Plate. It runs south from the Gulf of California in the Salton Sea basin in Southern California to a point near 55° S, 130° W, where it joins the Pacific-Antarctic Ridge trending west-southwest towards Antarctica, near New Zealand (though in some uses the PAR is regarded as the southern section of the EPR). Much of the rise lies about 3200 km (2000 mi) off the South American coast and rises about 1,800–2,700 m (6,000–9,000 ft) above the surrounding seafloor.

Fueguino

Fueguino is a volcanic field in Chile. The southernmost volcano in the Andes, it lies on Tierra del Fuego's Cook Island and also extends over nearby Londonderry Island. The field is formed by lava domes, pyroclastic cones, and a crater lake.

Volcanic activity at Fueguino is part of the Austral Volcanic Zone, which is formed by the subduction of the Antarctic Plate beneath the South America Plate. The subducting plate has not reached a depth sufficient for proper volcanic arc volcanism, however.

The field bears no trace of glacial erosion on its volcanoes, and reports exist of volcanic activity in 1712, 1820 and 1926.

Juan Fernández Plate

The Juan Fernandez Plate is a microplate in the Pacific Ocean. With a surface area of approximately 105 km2, the microplate is located between 32° and 35°S and 109° and 112°W. The plate is located at a triple junction between the Pacific Plate, Antarctic Plate, and Nazca Plate. Approximately 2000 km to the west of South America, it is, on average, 3000 meters deep with its shallowest point coming to approximately 1600 meters, and its deepest point reaching 4400 meters.

Kerguelen Plateau

The Kerguelen Plateau ( , ) is an oceanic plateau and a large igneous province (LIP) located on the Antarctic Plate, in the southern Indian Ocean. It is also a microcontinent and submerged continent. It is about 3,000 km (1,900 mi) to the southwest of Australia and is nearly three times the size of Japan. The plateau extends for more than 2,200 km (1,400 mi) in a northwest–southeast direction and lies in deep water.

The plateau was produced by the Kerguelen hotspot, starting with or following the breakup of Gondwana about 130 million years ago. A small portion of the plateau breaks sea level, forming the Kerguelen Islands (a French territory) plus the Heard and McDonald Islands (an Australian territory). Intermittent volcanism continues on the Heard and McDonald Islands.

Macquarie Triple Junction

The Macquarie Triple Junction is a geologically active tectonic boundary located at 61°30′S 161°0′E at which the Indo-Australian Plate, Pacific Plate, and Antarctic Plate collide and interact. The term Triple Junction is given to particular tectonic boundaries at which three separate tectonic plates meet at a specific, singular location. The Macquarie Triple Junction is located on the seafloor of the southern region of the Pacific Ocean, just south of New Zealand. This tectonic boundary was named in respect to the nearby Macquarie Island, which is located southeast of New Zealand.

Nazca Plate

The Nazca Plate, named after the Nazca region of southern Peru, is an oceanic tectonic plate in the eastern Pacific Ocean basin off the west coast of South America. The ongoing subduction, along the Peru–Chile Trench, of the Nazca Plate under the South American Plate is largely responsible for the Andean orogeny. The Nazca Plate is bounded on the west by the Pacific Plate and to the south by the Antarctic Plate through the East Pacific Rise and the Chile Rise respectively. The movement of the Nazca Plate over several hotspots has created some volcanic islands as well as east-west running seamount chains that subduct under South America. Nazca is a relatively young plate both in terms of the age of its rocks and its existence as an independent plate having been formed from the break-up of the Farallon Plate about 23 million years ago. The oldest rocks of the plate are about 50 million years old.

Pacific-Antarctic Ridge

The Pacific-Antarctic Ridge (PAR) is a divergent tectonic plate boundary located on the seafloor of the South Pacific Ocean, separating the Pacific Plate from the Antarctic Plate. It is regarded as the southern section of the East Pacific Rise in some usages, generally south of the Challenger Fracture Zone and stretching to the Macquarie Triple Junction south of New Zealand.

Phoenix Plate

The Phoenix Plate (also known as the Aluk or Drake Plate) was an ancient tectonic plate that existed during the mid-Cretaceous through early Cenozoic time. The remainder of the plate is now located east of the Drake Passage/Shackleton Fracture Zone.

The Phoenix Plate began subducting under the Antarctic Plate. The Phoenix Ridge, a mid-oceanic ridge between the Pacific and the Phoenix Plates which had a spreading rate of 18–20 cm per year until around 84 Ma. A major decrease in spreading rate, and the convergence rate with the Antarctic Plate occurred around 52.3 Ma. During the Late Cretaceous, the Phoenix Plate fragmented into the Charcot Plate, much in the same way in which the Rivera and the Cocos Plate were formed by the fragmentation of the Farallon Plate.The Antarctic-Phoenix Ridge (sometimes also called the Phoenix Ridge) consists of three extinct spreading ridge segments between the Antarctic Peninsula and the Scotia Sea. This ridge was initiated during the Late Cretaceous-Early Tertiary when the plate had divergent boundaries with the Bellingshausen and Pacific Plates. Bellingshausen was fused with the Antarctic Plate around 61 Ma and the Phoenix plate was gradually subducted by the Antarctic Plate as the Pacific-Antarctic Ridge propagated. The last collision between ridge crest segments and the subduction zone happened around 6.5 Ma and spreading had ceased entirely by 3.3 Ma when the small remnant of the Phoenix Plate was incorporated into the Antarctic Plate. The South Shetland Trough is the south-eastern boundary of the remnant and the Shackleton Fracture Zone is its north-eastern boundary.

Phoenix Ridge

The Phoenix Ridge (also called the Aluk Ridge) was an ancient mid-ocean ridge that existed between the Phoenix Plate and the Pacific Plate. The Phoenix Ridge consisted of three ridges and had a spreading rate of 18–20 cm per year until around 84 Ma. A major decrease in spreading rate, and the convergence rate with the Antarctic Plate occurred around 52.3 Ma. The Phoenix Ridge has since been subducted under the Antarctic Peninsula in the Miocene period.

Scotia Plate

The Scotia Plate (Spanish: Placa Scotia) is a tectonic plate on the edge of the South Atlantic and Southern Ocean. Thought to have formed during the early Eocene with the opening of the Drake Passage that separates South America from Antarctica, it is a minor plate whose movement is largely controlled by the two major plates that surround it: the South American Plate and Antarctic Plate.Roughly rhomboid, extending between 50°S 70°W and 63°S 20°W, the plate is 800 km (500 mi) wide and 3,000 km (1,900 mi) long. It is moving WSW at 2.2 cm (0.87 in)/year and the South Sandwich Plate is moving east at 5.5 cm (2.2 in)/year in an absolute reference frame. It takes its name from the steam yacht Scotia of the Scottish National Antarctic Expedition (1902–04), the expedition that made the first bathymetric study of the region.The Scotia Plate is made of oceanic crust and continental fragments now distributed around the Scotia Sea. Before the formation of the plate began 40 million years ago (40Ma), these fragments formed a continuous landmass from Patagonia to the Antarctic Peninsula along an active subduction margin. At present the plate is almost completely submerged, with only the small exceptions of the South Georgia Islands on its northeastern edge and the southern tip of South America.

Shetland Plate

The Shetland Plate is a tectonic microplate located off the tip of the Antarctic Peninsula and contains the South Shetland Islands. The plate is bordered on three sides by the Antarctic Plate and the fourth side is bordered by the Scotia Plate. The northwestern border is defined by the South Shetland Trench separating the Shetland Plate to the south from the Antarctic Plate to the north. This trench is the remnant of a subduction zone where the defunct Phoenix Plate, now part of the Antarctic Plate, subducted under the Antarctic Peninsula and the Shetland Islands. The southeastern border is rift zone with the Antarctic Plate creating the Bransfield Basin. The southwestern and northeastern boundaries are each part of larger fracture zones. The southwestern border is the Hero Fracture Zone and separates the Antarctic Plate to the southwest from the Shetland Plate to the northeast. The northeastern boundary is the Shackleton Fracture Zone and separates the Shetland Plate to the southwest from the Scotia Plate.

South American Plate

The South American Plate is a major tectonic plate which includes the continent of South America as well as a sizable region of the Atlantic Ocean seabed extending eastward to the African Plate, with which it forms the southern part of the Mid-Atlantic Ridge.

The easterly edge is a divergent boundary with the African Plate; the southerly edge is a complex boundary with the Antarctic Plate, the Scotia Plate, and the Sandwich Plate; the westerly edge is a convergent boundary with the subducting Nazca Plate; and the northerly edge is a boundary with the Caribbean Plate and the oceanic crust of the North American Plate. At the Chile Triple Junction, near the west coast of the Taitao–Tres Montes Peninsula, an oceanic ridge known as the Chile Rise is actively subducting under the South American Plate.

Geological research suggests that the South American Plate is moving westward away from the Mid-Atlantic Ridge: "Parts of the plate boundaries consisting of alternations of relatively short transform fault and spreading ridge segments are represented by a boundary following the general trend." As a result, the eastward-moving and more dense Nazca Plate is subducting under the western edge of the South American Plate, along the continent's Pacific coast, at a rate of 77 mm (3.0 in) per year. The collision of these two plates is responsible for lifting the massive Andes Mountains and for creating the numerous volcanoes which are strewn throughout them.

South American–Antarctic Ridge

The South American–Antarctic Ridge (SAAR or AAR) is the tectonic spreading center between the South American Plate and the Antarctic Plate. It runs along the sea-floor from the Bouvet Triple Junction in the South Atlantic Ocean south-westward to a major transform fault boundary east of the South Sandwich Islands. Near the Bouvet Triple Junction the spreading half rate is 9 mm/a (0.35 in/year), which is slow, and the SAAR has the rough topography characteristic of slow-spreading ridges.

South Sandwich Plate

The South Sandwich Plate or Sandwich Plate is a minor tectonic plate bounded by the subducting South American Plate to the east, the Antarctic Plate to the south and the Scotia Plate to the west. The plate is separated from the Scotia Plate by the East Scotia Rise, a back arc spreading ridge formed by the subduction zone on its eastern margin.

The South Sandwich Islands are located on this small plate.

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