In plate tectonics, a divergent boundary or divergent plate boundary is a linear feature that exists between two tectonic plates that are moving away from each other. Divergent boundaries within continents initially produce rifts, which eventually become rift valleys. Most active divergent plate boundaries occur between oceanic plates and exist as mid-oceanic ridges.
A convergent boundary is an area on Earth where two or more lithospheric plates collide. One plate eventually slides beneath the other, a process known as subduction. The subduction zone can be defined by a plane where many earthquakes occur, called the Wadati–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.
The North American plate is a tectonic plate containing most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of 76 million km2 (29 million sq mi), it is the Earth's second largest tectonic plate, behind the Pacific plate.
The Nazca plate or Nasca 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 in terms of the age of its rocks and its existence as an independent plate, having been formed from the breakup of the Farallon plate about 23 million years ago. The oldest rocks of the plate are about 50 million years old.
The Trans-Mexican Volcanic Belt, also known as the Transvolcanic Belt and locally as the Sierra Nevada, is an active 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.
The Caribbean plate is a mostly oceanic tectonic plate underlying Central America and the Caribbean Sea off the northern coast of South America.
The Central American Volcanic Arc is a chain of volcanoes which extends parallel to the Pacific coastline of the Central American Isthmus, from Mexico to Panama. This volcanic arc, which has a length of 1,100 kilometers (680 mi) is formed by an active subduction zone, with the Cocos plate subducting underneath the Caribbean plate, the North American plate and the Panama plate. Volcanic activity is recorded in the Central American region since the Permian. Numerous volcanoes are spread throughout various Central American countries; many have been active in the geologic past, varying in intensity of their activity according to different factors.
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 Galápagos microplate (GMP) is a geological feature of the oceanic crust located at 1°50' N, offshore of the west coast of Colombia. The GMP is collocated with the Galápagos triple junction (GTJ), which is an atypical ridge–ridge–ridge triple junction. At the GTJ, the Pacific plate, Cocos plate, and Nazca plate meet incompletely, forming two counter-rotating microplates at the junction of the Cocos–Nazca, Pacific–Cocos, and Pacific–Nazca spreading ridges.
The Galápagos hotspot is a volcanic hotspot in the East Pacific Ocean responsible for the creation of the Galápagos 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 Galápagos 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 Galápagos triple junction (GTJ) is a geological area in the eastern Pacific Ocean several hundred miles west of the Galápagos Islands where three tectonic plates – the Cocos plate, the Nazca plate, and the Pacific plate – meet. It is an unusual type of triple junction in which the three plates do not meet at a simple intersection. Instead, the junction includes two small microplates, the Galápagos microplate and the northern Galápagos microplate, caught in the junction, turning synchronously with respect to each other and separated by the Hess Deep rift.
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.
The Panama plate is a small tectonic plate (microplate) that exists between two actively spreading ridges and moves relatively independently of its surrounding plates. The Panama plate is located between the Cocos plate and the Nazca plate to the south and the Caribbean plate to the north. Most of its borders are convergent boundaries, including a subduction zone to the west. It consists, for the most part, of the countries of Costa Rica and Panama.
This is a list of articles related to plate tectonics and tectonic plates.
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. A broader definition of flat slab subduction includes 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 deform or buckle, 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.
The Coiba plate is a small tectonic plate (microplate) 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.
The geology of Costa Rica is part of the Panama Microplate, which is slowly moving north relative to the stable Caribbean Plate.
The Chile Ridge, also known as the Chile Rise, is a submarine oceanic ridge formed by the divergent plate boundary between the Nazca plate and the Antarctic plate. It extends from the triple junction of the Nazca, Pacific, and Antarctic plates to the Southern coast of Chile. The Chile Ridge is easy to recognize on the map, as the ridge is divided into several segmented fracture zones which are perpendicular to the ridge segments, showing an orthogonal shape toward the spreading direction. The total length of the ridge segments is about 550–600 km.
