Cocos Plate

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Cocos Plate
CocosPlate.png
Type Minor
Approximate area 2,900,000 km2 [1]
Movement1 north-east
Speed1 67mm/year
Features Cocos Island, Pacific Ocean
1Relative to the African Plate

The Cocos Plate is a young oceanic tectonic plate beneath the Pacific Ocean off the west coast of Central America, named for Cocos Island, which rides upon it. The Cocos Plate was created approximately 23 million years ago when the Farallon Plate broke into two pieces, which also created the Nazca Plate. The Cocos Plate also broke into two pieces, creating the small Rivera Plate. [2] The Cocos Plate is bounded by several different plates. To the northeast it is bounded by the North American Plate and the Caribbean Plate. To the west it is bounded by the Pacific Plate and to the south by the Nazca Plate.

Pacific Ocean Ocean between Asia and Australia in the west, the Americas in the east and Antarctica or the Southern Ocean in the south.

The Pacific Ocean is the largest and deepest of Earth's oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean in the south and is bounded by Asia and Australia in the west and the Americas in the east.

Central America central geographic region of the Americas

Central America is located on the southern tip of North America, or is sometimes defined as a subcontinent of the Americas, bordered by Mexico to the north, Colombia to the southeast, the Caribbean Sea to the east, and the Pacific Ocean to the west and south. Central America consists of seven countries: Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, and Panama. The combined population of Central America has been estimated to be 41,739,000 and 42,688,190.

Cocos Island An island designated as a National Park off the shore of Costa Rica

Cocos Island is an island in the Pacific Ocean administered by Costa Rica, approximately 550 km southwest of the Costa Rican mainland. It constitutes the 11th of the 13 districts of Puntarenas Canton of the Province of Puntarenas. With an area of approximately 23.85 km2 (9.21 sq mi), the island is more or less rectangular in shape. It is the southernmost point on the North American continent if outer islands are included.

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Geology

The Cocos Plate was created by sea floor spreading along the East Pacific Rise and the Cocos Ridge, specifically in a complicated area geologists call the Cocos-Nazca spreading system. From the rise the plate is pushed eastward and pushed or dragged (perhaps both) under the less dense Caribbean Plate, in the process called subduction. The subducted leading edge heats up and adds its water to the mantle above it. In the mantle layer called the asthenosphere, mantle rock melts to make magma, trapping superheated water under great pressure. As a result, to the northeast of the subducting edge lies the continuous arc of volcanos —also known as the Central America Volcanic Arc— stretching from Costa Rica to Guatemala, and a belt of earthquakes that extends farther north, into Mexico.

East Pacific Rise A mid-oceanic ridge at a divergent tectonic plate boundary on the floor of the Pacific Ocean

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 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. 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.

Caribbean Plate A mostly oceanic tectonic plate including part of Central America and the Caribbean Sea

The Caribbean Plate is a mostly oceanic tectonic plate underlying Central America and the Caribbean Sea off the north coast of South America.

Subduction A geological process at convergent tectonic plate boundaries where one plate moves under the other

Subduction is a geological process that takes place at convergent boundaries of tectonic plates where one plate moves under another and is forced to sink due to gravity into the mantle. Regions where this process occurs are known as subduction zones. Rates of subduction are typically in centimeters per year, with the average rate of convergence being approximately two to eight centimeters per year along most plate boundaries.

The northern boundary of the Cocos Plate is the Middle America Trench. The eastern boundary is a transform fault, the Panama Fracture Zone. The southern boundary is a mid-oceanic ridge, the Galapagos Rise. [3] The western boundary is another mid-ocean ridge, the East Pacific Rise.

Middle America Trench A subduction zone in the eastern Pacific off the southwestern coast of Middle America

The Middle America Trench is a major subduction zone, an oceanic trench in the eastern Pacific Ocean off the southwestern coast of Middle America, stretching from central Mexico to Costa Rica. The trench is 1,700 miles (2,750 km) long and is 21,880 feet at its deepest point. The trench is the boundary between the Rivera, Cocos, and Nazca plates on one side and the North American and Caribbean plates on the other. It is the 18th-deepest trench in the world. Many large earthquakes have occurred in the area of the Middle America Trench.

Transform fault A plate boundary where the motion is predominantly horizontal

A transform fault or transform boundary is a plate boundary where the motion is predominantly horizontal. It ends abruptly and is connected to another transform, a spreading ridge, or a subduction zone.

The Panama Fracture Zone is a major, active right lateral-moving transform fault and associated inactive fracture zone which forms part of the tectonic boundary between the Cocos Plate and the Nazca Plate. It is part of the triple junction between the Cocos Plate, Nazca Plate and Caribbean Plate which is moving in the southeastern direction at 5.5 cm/yr. It runs from the East Pacific Rise to the Middle America Trench.

A hotspot under the Galapagos Islands lies along the Galapagos Rise. (see Galapagos hotspot)

Hotspot (geology) Volcanic regions thought to be fed by underlying mantle that is anomalously hot compared with the surrounding mantle

In geology, the places known as hotspots or hot spots are volcanic regions thought to be fed by underlying mantle that is anomalously hot compared with the surrounding mantle. Their position on the Earth's surface is independent of tectonic plate boundaries. There are two hypotheses that attempt to explain their origins. One suggests that hotspots are due to mantle plumes that rise as thermal diapirs from the core–mantle boundary. The other hypothesis is that lithospheric extension permits the passive rising of melt from shallow depths. This hypothesis considers the term "hotspot" to be a misnomer, asserting that the mantle source beneath them is, in fact, not anomalously hot at all. Well-known examples include the Hawaii, Iceland and Yellowstone hotspots.

The Rivera Plate north of the Cocos Plate is thought to have separated from the Cocos Plate 5–10 million years ago. The boundary between the two plates appears to lack a definite transform fault, yet they are regarded as distinct. After its separation from the Cocos Plate, the Rivera Plate started acting as an independent microplate. [4]

Rivera Plate Small tectonic plate off the west coast of Mexico

The Rivera Plate is a small tectonic plate located off the west coast of Mexico, just south of the Baja California Peninsula. It is bounded on the northwest by the East Pacific Rise, on the southwest by the Rivera Transform Fault, on the southeast by a deformation zone, and on the northeast by the Middle America Trench and another deformation zone.

The devastating 1985 Mexico City earthquake and the 2017 Chiapas earthquake were results of the subduction of the Cocos Plate beneath the North American Plate. The also devastating 2001 El Salvador earthquakes were generated in the subduction of this plate on the Caribbean Plate.

1985 Mexico City earthquake September 19th, 1985 earthquake in Mexico City, Mexico

The 1985 Mexico City earthquake struck in the early morning of 19 September at 07:17:50 (CST) with a moment magnitude of 8.0 and a Mercalli intensity of IX (Violent). The event caused serious damage to the Greater Mexico City area and the deaths of at least 5,000 people. The sequence of events included a foreshock of magnitude 5.2 that occurred the prior May, the main shock on 19 September, and two large aftershocks. The first of these occurred on 20 September with a magnitude of 7.5 and the second occurred seven months later on 30 April 1986 with a magnitude of 7.0. They were located off the coast along the Middle America Trench, more than 350 kilometres (220 mi) away, but the city suffered major damage due to its large magnitude and the ancient lake bed that Mexico City sits on. The event caused between three and four billion USD in damage as 412 buildings collapsed and another 3,124 were seriously damaged in the city.

2017 Chiapas earthquake 8.2 earthquake with epicenter in Chiapas,

The 2017 Chiapas earthquake struck at 23:49 CDT on 7 September in the Gulf of Tehuantepec off the southern coast of Mexico, near state of Chiapas, approximately 87 kilometres (54 mi) southwest of Pijijiapan, with a Mercalli intensity of IX (Violent). The magnitude was estimated to be Mw 8.2.

North American Plate Large tectonic plate including most of North America, Greenland and a bit of Siberia

The North American Plate is a tectonic plate covering most of North America, Greenland, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. It extends eastward to the Mid-Atlantic Ridge and westward to the Chersky Range in eastern Siberia. The plate includes both continental and oceanic crust. The interior of the main continental landmass includes an extensive granitic core called a craton. Along most of the edges of this craton are fragments of crustal material called terranes, accreted to the craton by tectonic actions over a long span of time. It is thought that much of North America west of the Rocky Mountains is composed of such terranes.

Related Research Articles

Convergent boundary Region of active deformation between colliding lithospheric plates

Convergent boundaries are areas on Earth where two or more lithospheric plates collide. One plate eventually slides beneath the other causing a process known as subduction. The subduction zone can be defined by a plane where many earthquakes occur, called the Benioff Zone. These collisions happen on scales of millions to tens of millions of years and can lead to volcanism, earthquakes, orogenesis, destruction of lithosphere, and deformation. Convergent boundaries occur between oceanic-oceanic lithosphere, oceanic-continental lithosphere, and continental-continental lithosphere. The geologic features related to convergent boundaries vary depending on crust types.

Farallon Plate An ancient oceanic plate that has mostly subducted under the west coast of the North American Plate

The Farallon Plate was an ancient oceanic plate that began subducting under the west coast of the North American Plate—then located in modern Utah—as Pangaea broke apart during the Jurassic period. It is named for the Farallon Islands, which are located just west of San Francisco, California.

Nazca Plate Oceanic tectonic plate in the eastern Pacific Ocean basin

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.

Ridge push or sliding plate force is a proposed driving force for plate motion in plate tectonics that occurs at mid-ocean ridges as the result of the rigid lithosphere sliding down the hot, raised asthenosphere below mid-ocean ridges. Although it is called ridge push, the term is somewhat misleading; it is actually a body force that acts throughout an ocean plate, not just at the ridge, as a result of gravitational pull. The name comes from earlier models of plate tectonics in which ridge push was primarily ascribed to upwelling magma at mid-ocean ridges pushing or wedging the plates apart.

Trans-Mexican Volcanic Belt arc of volcanic mountains across central-southern Mexico

The Trans-Mexican Volcanic Belt, also known as the Transvolcanic Belt and locally as the Sierra Nevada, is a volcanic belt that covers central-southern Mexico. Several of its highest peaks have snow all year long, and during clear weather, they are visible to a large percentage of those who live on the many high plateaus from which these volcanoes rise.

Carnegie Ridge An aseismic ridge on the Nazca Plate that is being subducted beneath the South American Plate

The Carnegie Ridge is an aseismic ridge on the Nazca Plate that is being subducted beneath the South American Plate. The ridge is thought to be a result of the passage of the Nazca Plate over the Galapagos hotspot. It is named for the research vessel Carnegie, which discovered it in 1929.

The Caribbean large igneous province (CLIP) consists of a major flood basalt, which created this large igneous province (LIP). It is the source of the current large eastern Pacific oceanic plateau, of which the Caribbean-Colombian oceanic plateau is the tectonized remnant. The deeper levels of the plateau have been exposed on its margins at the North and South American plates. The volcanism took place between 139 and 69 million years ago, with the majority of activity appearing to lie between 95 and 88 Ma. The plateau volume has been estimated as on the order of 4 x 106 km³. It has been linked to the Galápagos hotspot.

Galápagos hotspot

The Galápagos hotspot is a volcanic hotspot in the East Pacific Ocean responsible for the creation of the Galapagos Islands as well as three major aseismic ridge systems, Carnegie, Cocos and Malpelo which are on two tectonic plates. The hotspot is located near the Equator on the Nazca Plate not far from the divergent plate boundary with the Cocos Plate. The tectonic setting of the hotspot is complicated by the Galapagos Triple Junction of the Nazca and Cocos plates with the Pacific Plate. The movement of the plates over the hotspot is determined not solely by the spreading along the ridge but also by the relative motion between the Pacific Plate and the Cocos and Nazca Plates.

The Tehuantepec Ridge is a linear undersea ridge located off the west coast of Mexico in the Pacific Ocean. It is the remnant of an old fracture zone, and not a tectonic spreading center ridge. It extends from the eastern end of the Clipperton Fracture Zone northeastward toward Mexico into Chiapas and El Chichón until it is subducted into the Middle America Trench. It lies within the tectonic Cocos Plate, separating the lower and older seafloor of the Guatemala Basin which lies southeast of the ridge from higher and younger seafloor which lies to its northwest.

Pacific-Farallon Ridge A spreading ridge during the late Cretaceous that separated the Pacific Plate to the west and the Farallon Plate to the east

The Pacific-Farallon Ridge was a spreading ridge during the late Cretaceous that extended 10,000 km in length and separated the Pacific Plate to the west and the Farallon Plate to the east. It ran south from the Pacific-Farallon-Kula triple junction at 51°N to the Pacific-Farallon-Antarctic triple junction at 43°S. As the Farallon Plate subducted obliquely under the North American Plate, the Pacific-Farallon Ridge approached and eventually made contact with the North American Plate about 30 million years ago. On average, this ridge had an equatorial spreading rate of 13.5 cm per year until its eventual collision with the North American Plate. In present day, the Pacific-Farallon Ridge no longer formally exists since the Farallon Plate has been broken up or subducted beneath the North American Plate, and the ridge has segmented, having been mostly subducted as well. The most notable remnant of the Pacific-Farallon Ridge is the 4000 km Pacific-Nazca segment of the East Pacific Rise.

This is a list of articles related to plate tectonics and tectonic plates.

Geology of the Pacific Ocean

The Pacific Ocean evolved in the Mesozoic from the Panthalassic Ocean, which had formed when Rodinia rifted apart around 750 Ma. The first ocean floor which is part of the current Pacific Plate began 160 Ma to the west of the central Pacific and subsequently developed into the largest oceanic plate on Earth.

Flat slab subduction is characterized by a low subduction angle beyond the seismogenic layer and a resumption of normal subduction far from the trench. A slab refers to the subducting lower plate. Although, some would characterize flat slab subduction as any shallowly dipping lower plate as in western Mexico. Flat slab subduction is associated with the pinching out of the asthenosphere, an inland migration of arc magmatism, and an eventual cessation of arc magmatism. The coupling of the flat slab to the upper plate is thought to change the style of deformation occurring on the upper plate's surface and form basement-cored uplifts like the Rocky Mountains. The flat slab also may hydrate the lower continental lithosphere and be involved in the formation of economically important ore deposits. During the subduction, a flat slab itself may be deformed, or buckling, causing sedimentary hiatus in marine sediments on the slab. The failure of a flat slab is associated with ignimbritic volcanism and the reverse migration of arc volcanism. Multiple working hypotheses about the cause of flat slabs are subduction of thick, buoyant oceanic crust (15–20 km) and trench rollback accompanying a rapidly overriding upper plate and enhanced trench suction. The west coast of South America has two of the largest flat slab subduction zones. Flat slab subduction is occurring at 10% of subduction zones.

Coiba Plate A small tectonic plate off the coast south of Panama and northwestern Colombia

The Coiba Plate is a small tectonic plate located off the coasts south of Panama and northwestern Colombia. It is named after Coiba, the largest island of Central America, just north of the plate offshore southern Panama. It is bounded on the west by the Cocos Plate, on the south by the Malpelo Plate, on the east by the North Andes Plate, and on the north by the Panama Plate. This microplate was previously assumed to be part of the Nazca Plate, forming the northeastern tongue of the Nazca Plate together with the Malpelo Plate. Bordering the Coiba Plate on the east are the north-south striking Bahía Solano Fault and east of that, the Serranía de Baudó, an isolated mountain chain in northwestern Chocó, Colombia.

References

  1. "Here are the Sizes of Tectonic or Lithospheric Plates".
  2. Manea, V.C.; Manea, M.; Ferarri, L. (2013). "A geodynamical perspective on the subduction of Cocos and Rivera plates beneath Mexico and Central America" (PDF). Tectonophysics. 609: 56–81. doi:10.1016/j.tecto.2012.12.039 . Retrieved 24 April 2017.
  3. Paul J. Grim, "Connection of the Panama fracture zone with the Galapagos rift zone, eastern tropical Pacific".
  4. Manea, V.C.; Manea, M.; Ferarri, L. (2013). "A geodynamical perspective on the subduction of Cocos and Rivera plates beneath Mexico and Central America" (PDF). Tectonophysics. 609: 56–81. doi:10.1016/j.tecto.2012.12.039 . Retrieved 24 April 2017.