Juan Fernández Ridge

The Juan Fernández Ridge is a volcanic island and seamount chain on the Nazca Plate. It runs in a west–east direction from the Juan Fernández hotspot to the Peru–Chile Trench at a latitude of 33° S near Valparaíso. The Juan Fernández Islands are the only seamounts that reach the surface.

Subduction of the ridge beneath South America is thought to have caused the Pampean flat-slab and its associated inland tectonic deformation and reduced magmatic acticity.[1][2]

Map of the volcanic arcs in the Andes and subducted structures affecting volcanism


  1. ^ Ramos, Victor A.; Cristallini, E.O.; Pérez, Daniel J. (2002). "The Pampean flat-slab of the Central Andes". Journal of South American Earth Sciences. 15: 59–78.
  2. ^ Stern, Charles R (December 2004). "Active Andean volcanism: its geologic and tectonic setting". Revista Geológica de Chile. 31 (2): 161–206. doi:10.4067/S0716-02082004000200001. ISSN 0716-0208. Retrieved 2008-11-20.
  • von Huene, R.; Corvalán, J.; Flueh, E. R.; Hinz, K.; Korstgard, J.; Ranero, C. R.; Weinrebe, W. (1997), "Tectonic control of the subducting Juan Fernández Ridge on the Andean margin near Valparaiso, Chile", Tectonics, 16 (3): 474–488, doi:10.1029/96TC03703
Amazon Basin (sedimentary basin)

The Amazon Basin is a major 620,000 square kilometres (240,000 sq mi) large sedimentary basin located roughly at the middle and lower course of the Amazon River, south the Guiana Shield and north of the Central Brazilian Shield. It is bound to the west by the Púrus Arch, separating the Amazon Basin from the Solimões Basin and in the east by the Gurupá Arch, separating the basin from the Marajó Basin. The basin developed on a rift that originated possibly about 550 million years ago during the Cambrian. Parts of the rift were reactivated during the opening of the South Atlantic.The basin has an elongated shape with a WSW-ENE orientation. It long axis runs from the vicinity of Manaus to the area near the confluence of Xingu River with the Amazon River.

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.


The Andes or Andean Mountains (Spanish: Cordillera de los Andes) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The Andes also have the 2nd most elevated highest peak of any mountain range, only behind the Himalayas. The range is 7,000 km (4,300 mi) long, 200 to 700 km (120 to 430 mi) wide (widest between 18° south and 20° south latitude), and has an average height of about 4,000 m (13,000 ft). The Andes extend from north to south through seven South American countries: Venezuela, Colombia, Ecuador, Peru, Bolivia, Chile and Argentina.

Along their length, the Andes are split into several ranges, separated by intermediate depressions. The Andes are the location of several high plateaus – some of which host major cities such as Quito, Bogotá, Cali, Arequipa, Medellín, Bucaramanga, Sucre, Mérida and La Paz. The Altiplano plateau is the world's second-highest after the Tibetan plateau. These ranges are in turn grouped into three major divisions based on climate: the Tropical Andes, the Dry Andes, and the Wet Andes.

The Andes Mountains are the highest mountain range outside Asia. The highest mountain outside Asia, Argentina's Mount Aconcagua, rises to an elevation of about 6,961 m (22,838 ft) above sea level. The peak of Chimborazo in the Ecuadorian Andes is farther from the Earth's center than any other location on the Earth's surface, due to the equatorial bulge resulting from the Earth's rotation. The world's highest volcanoes are in the Andes, including Ojos del Salado on the Chile-Argentina border, which rises to 6,893 m (22,615 ft).

The Andes are also part of the American Cordillera, a chain of mountain ranges (cordillera) that consists of an almost continuous sequence of mountain ranges that form the western "backbone" of North America, Central America, South America and Antarctica.

Boconó Fault

The Boconó Fault is a complex of geological fault located in the Eastern Ranges of northeastern Colombia and the Mérida Andes of northwestern Venezuela. The fault has a NE-SW orientation. Boconó Fault is a strike-slip fault and has a dextral relative movement. The fault extends over a length of 500 kilometres (310 mi). The fault, with a slip rate ranging from 4.3 to 6.1 millimetres (0.17 to 0.24 in) per year, has been active since the Early Holocene and earthquakes of 1610 and 1894 are associated with the Boconó Fault.

Caldera Basin

Caldera Basin (Spanish: Cuenca de Caldera) is a sedimentary basin located in the coast of northern Chile west of Copiapó. The basin has a fill of marine sediments of Late Cenozoic age. With a north-south extension of 43 kilometres (27 mi) and an east-west width of 20 kilometres (12 mi) the basin occupies an area between the coast and the Chilean Coast Range and between the port of Caldera and the mouth of Copiapó River. The sedimentary fill rests on metamorphic rocks of Paleozoic age and on plutonic rocks of Mesozoic age.

Cerro Ballena

Cerro Ballena (lit. "Whale Hill") is a Chilean Late Miocene palaeontological site hosting remains of cetaceans. It is located in the Atacama Desert along the Pan-American Highway a few kilometers north of the port of Caldera. Besides cetaceans Cerro Ballena does also contains fossils of pinnipeds, sailfishes, aquatic sloths and marine invertebrate as well as trace fossils. It has about 40 cetacean individuals all of them in relatively good state. The cetaceans appear to have died at different times but due to the same causes: poisoning by toxins secreted by algae. The site was discovered in 2011 and is protected by law since 2012. It hosts an investigation centre.As of February 2014 scientists from Brazil, Chile and the United States were studying the site.Geologically Cerro Ballena is part of the Cerro Ballena Member of Bahía Inglesa Formation.

Chile Fracture Zone

The Chile Fracture Zone (CFZ) is a major strike slip fault and fracture zone in the Chile Rise. The Chile Fracture Zone runs in an eastwest direction almost parallel to nearby Juan Fernández Ridge and makes up a large part of the Antarctic—Nazca Plate boundary.


Chilenia was an ancient microcontinent or terrane whose history affected many of the older rocks of central Chile and western Argentina. It was once separated by oceanic crust from the Cuyania terrane to which it accreted at ~420-390 Ma when Cuyania was already amalgamated with Gondwana.

Chiloé Block

The Chiloé Block or Chiloé Terrane is a geotectonic unit making up the basement of large parts of south-central Chile between 41° and 45°S. Due to its form it is sometimes called Chiloé Sliver. The Chiloé Block is believed to be an ancient microcontinent or terrane that collided with the South American Plate during the Proterozoic. The Chiloé Sliver is however badly sutured to South America as the Liquiñe-Ofqui Fault runs through its eastern boundary.


The Precordillera Terrane or Cuyania was an ancient microcontinent or terrane whose history affected many of the older rocks of Cuyo in Argentina. It was separated by oceanic crust from the Chilenia terrane which accreted into it at ~420-390 Ma when Cuyania was already amalgamated with Gondwana. The hypothesized Mejillonia Terrane in the coast of northern Chile is considered by some geologists to be a single block with Cuyania.

The San Rafael Block crops out 200 km to the south of the other exposures of Cuyania and is the southern extension of the terrane.The Precordillera has been hypothesised to have been derived from Laurentia, the core of North America, which was attached to the western margin of South America during the Precambrian when virtually all continents formed a "proto-Gondwana" supercontinent known as Pannotia. The Precordillera was then part of a proposed "Texas Plateau", a promontory attached to Laurentia similar to the way the Falkland Plateau is attached to South America today. The Texas Plateau was detached from the Gondwana in a rift around 455 Ma after which it collided with the proto-Andean margin of South America, an event known as the Taconic-Famatinian orogeny, and the Precordillera got left behind at its present location within South America.

Hotspot (geology)

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.

Juan Fernández hotspot

The Juan Fernández hotspot is a volcanic hotspot located in the southeastern Pacific Ocean. The hotspot created the Juan Fernández Ridge which includes the Juan Fernández Archipelago and a long seamount chain that is being subducted in the Peru–Chile Trench at the site of Papudo giving origin to the Norte Chico Volcanic Gap.

Natural regions of Chile

Because Chile extends from a point about 625 kilometers north of the Tropic of Capricorn to a point hardly more than 1,400 kilometers north of the Antarctic Circle, within its territory can be found a broad selection of the Earth's climates.

In 1950, CORFO defined, following criteria of geographic and economic homogeneity, six regions in continental Chile: Norte Grande, Norte Chico, Núcleo Central, Concepción y La Frontera, Los Lagos and Los Canales.Although this territorial division was never used to define administrative entities (as the current Regions of Chile), the natural regions continue to be used for reference purposes.

Oca-Ancón Fault System

The Oca-Ancón Fault System (Spanish: Falla Oca-Ancón) is a complex of geological faults located in the northeastern Colombia and northwestern Venezuela near the Caribbean Sea. The fault system is of right-lateral strike-slip type and extends for an approximate length of 830 km (520 mi). The Oca-Ancón Fault System is part of the diffuse boundary between the Caribbean Plate and the South American Plate. The movement rate of the Oca-Ancón Fault System is estimated at 2 millimetres (0.079 in) each year, more than most Venezuelan faults.

Pampean flat-slab

The Pampean flat-slab is the low angle subduction of oceanic lithosphere beneath northern Chile and Argentina. The Pampean flat-slab is one of three flat slabs in South America, the other being the Peruvian flat-slab and the Bucaramanga flat-slab.It is thought that the subduction of Juan Fernández Ridge, a chain of extinct volcanoes in Nazca Plate, is the underlying cause of the Pampean flat-slab.


Pampia was an ancient microcontinent or terrane that collided with Río de la Plata Craton and Río Apas Craton during the Pampean orogeny of late Proterozoic and early Cambrian. It was one of the first terranes to be amalgamated to the old cratons of the east, and was followed by the suturing of Cuyania and Chilenia terranes into the young South American Plate.

Peru–Chile Trench

The Peru–Chile Trench, also known as the Atacama Trench, is an oceanic trench in the eastern Pacific Ocean, about 160 kilometres (100 mi) off the coast of Peru and Chile. It reaches a maximum depth of 8,065 meters (26,460 ft) below sea level in Richards Deep (23°10′45″S 71°18′41″W) and is approximately 5,900 kilometres (3,666 mi) long; its mean width is 64 kilometres (40 mi) and it covers an expanse of some 590,000 square kilometres (228,000 mi²).

The trench delineates the boundary between the subducting Nazca Plate and the overriding South American Plate.


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.[1] 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.Plates include both oceanic crust and continental crust. Stable subduction zones involve the oceanic lithosphere of one plate sliding beneath the continental or oceanic lithosphere of another plate due to the higher density of the oceanic lithosphere. That is, the subducted lithosphere is always oceanic while the overriding lithosphere may or may not be oceanic. Subduction zones are sites that usually have a high rate of volcanism and earthquakes. Furthermore, subduction zones develop belts of deformation and metamorphism in the subducting crust, whose exhumation is part of orogeny and also leads to mountain building in addition to collisional thickening.

and groups


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