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Information about Island Arc

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Mariana Islands, an oceanic island arc
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Cascade Volcanic Arc, a continental volcanic arc


A volcanic arc is chain of volcanic islands or mountains formed by plate tectonics as an oceanic tectonic plate subducts under another tectonic plate and produces magma. There are two types of volcanic arcs: oceanic arcs (commonly called island arcs, a type of archipelago) and continental arcs. In the former, oceanic crust subducts beneath other oceanic crust on an adjacent plate, while in the latter case the oceanic crust subducts beneath continental crust. In some situations, a single subduction zone may show both aspects along its length, as part of a plate subducts beneath a continent and part beneath adjacent oceanic crust.

Two classic examples of oceanic island arcs are the Mariana Islands in the western Pacific Ocean and the Lesser Antilles in the western Atlantic Ocean. The Cascade Volcanic Arc in western North America and the Andes along the western edge of South America are examples of continental volcanic arcs. The best examples of volcanic arcs with both sets of characteristics are in the North Pacific, with the Aleutian Arc consisting of the Aleutian Islands and their extension the Aleutian Range on the Alaska Peninsula, and the Kuril-Kamchatka Arc comprising the Kuril Islands and southern Kamchatka Peninsula.

Petrology

In the subduction zone, loss of volatiles from the subducted slab induces partial melting of the overriding mantle and generates low-density, calc-alkaline magma that buoyantly rises to intrude and be extruded through the lithosphere of the overriding plate.

On the subducting side of the island arc is a deep and narrow oceanic trench, which is the trace at the Earth’s surface of the boundary between the downgoing and overriding plates. This trench is created by the gravitational pull of the relatively dense subducting plate pulling the leading edge of the plate downward. Multiple earthquakes occur along this subduction boundary with the seismic hypocenters located at increasing depth under the island arc: these quakes define the Wadati-Benioff zones.

Ocean basins that are being reduced by subduction are called 'remnant oceans' as they will slowly be shrunken out of existence and crushed in the subsequent orogenic collision. This process has happened over and over in the geologic history of the Earth.

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The Aleutian Arc, with both oceanic and continental parts.

Examples

Continental arcs

Island arcs

Ancient Island arcs

See also

References

Volcano:
1. Large magma chamber
2. Bedrock
3. Conduit (pipe)
4. Base
5. Sill
6. Branch pipe
7. Layers of ash emitted by the volcano
8. Flank 9. Layers of lava emitted by the volcano
10. Throat
11. Parasitic cone
12. Lava flow
13. Vent
14.
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island (IPA: /aɪ.lɪnd/) or isle (IPA: /aɪ.ʌl
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mountain is a landform that extends above the surrounding terrain in a limited area. A mountain is generally steeper than a hill, but there is no universally accepted standard definition for the height of a mountain or a hill although a mountain usually has an identifiable
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Plate tectonics (from Greek τέκτων, tektōn "builder" or "mason") is a theory of geology that has been developed to explain the observed evidence for large scale motions of the Earth's lithosphere.
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Plate tectonics (from Greek τέκτων, tektōn "builder" or "mason") is a theory of geology that has been developed to explain the observed evidence for large scale motions of the Earth's lithosphere.
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subduction zone is an area on Earth where two tectonic plates meet and move towards one another, with one sliding underneath the other and moving down into the mantle, at rates typically measured in centimeters per year.
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Magma (Plurals: magmas and magmata) is molten rock located beneath the surface of the Earth (or any other terrestrial planet) that often collects in a magma chamber. Magma may contain suspended crystals and gas bubbles.
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archipelago is a chain or cluster of islands. The word archipelago literally means "chief sea", from Greek arkhon (arkhi-) ("leader") and pelagos ("sea").
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Oceanic crust is the part of Earth's lithosphere that surfaces in the ocean basins. Oceanic crust is primarily composed of mafic rocks, or sima. It is thinner than continental crust, or sial, generally less than 10 kilometers thick, however it is more dense, having a mean density
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The continental crust is the layer of granitic, sedimentary, and metamorphic rocks which form the continents and the areas of shallow seabed close to their shores, known as continental shelves.
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For Ladrones Islands in South China Sea, please refer to Wanshan Qundao.
The Mariana Islands (also the Marianas; up to the early 20th century sometimes called Ladrones Islands, from Spanish Islas de los Ladrones
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Earth's oceans
(World Ocean)
  • Arctic Ocean
  • Atlantic Ocean
  • Indian Ocean
  • Pacific Ocean
  • Southern Ocean


The Pacific Ocean (from the Latin name Mare Pacificum
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Lesser Antilles, also known as the Caribbees,[1] are part of the Antilles, which together with the Bahamas and Greater Antilles form the West Indies. The islands are part of a long volcanic island arc, most of which wraps around the eastern end of the Caribbean
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Atlantic Ocean is the second-largest of the world's oceanic divisions; with a total area of about 106.4 million square kilometres (41.1 million square miles), it covers approximately one-fifth of the Earth's surface.
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The Cascade Volcanoes (also known as the Cascade Volcanic Arc or the Cascade Arc) are a volcanic arc which stretches from northern California to southwestern British Columbia, a distance of well over
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North America is a continent [1] in the Earth's northern hemisphere and (chiefly) western hemisphere. It is bordered on the north by the Arctic Ocean, on the east by the North Atlantic Ocean, on the southeast by the Caribbean Sea, and on the south and west
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Andes (Quechua: Anti(s/kuna))

The Andes between Chile and Argentina


Countries |
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South America is a continent of the Americas, situated entirely in the Western Hemisphere and mostly in the Southern Hemisphere. It is bordered on the west by the Pacific Ocean and on the north and east by the Atlantic Ocean; North America and the Caribbean Sea lie
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The Aleutian Islands (possibly from Chukchi aliat, "island") are a chain of more than 300 small volcanic islands forming an island arc in the Northern Pacific Ocean, occupying an area of 6,821 sq mi (17,666 km²) and extending about 1,200 mi (1,900 km) westward from the
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Aleutian Range



Country | United States
State | Alaska

Borders on Tordrillo Mountains


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Alaska Peninsula is a peninsula extending about 800 km (500 miles) to the southwest from the mainland of Alaska and ending in the Aleutian Islands. The peninsula separates the Pacific Ocean from Bristol Bay, an arm of the Bering Sea.
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Kuril Islands IPA: /kʊˈrɪl/ (Russian: Кури́льские острова́
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Kamchatka Peninsula (Russian: полуо́стров Камча́тка
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subduction zone is an area on Earth where two tectonic plates meet and move towards one another, with one sliding underneath the other and moving down into the mantle, at rates typically measured in centimeters per year.
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In planetary science, volatiles, commonly called ices in the extraterrestrial context, are that group of compounds with low boiling points (see volatile) that are associated with a planet's or moon's crust and/or atmosphere.
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mantle is a ~2,900 km thick rocky shell comprising approximately 70% of Earth's volume. It is predominantly solid and overlies the Earth's iron-rich core, which occupies about 30% of Earth's volume.
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Definition

Calc-alkaline and calc-alkalic are equivalent terms applied to groups of igneous rocks that commonly occur together and that have compositions related by the characteristic chemical trends specified below.
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Magma (Plurals: magmas and magmata) is molten rock located beneath the surface of the Earth (or any other terrestrial planet) that often collects in a magma chamber. Magma may contain suspended crystals and gas bubbles.
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intrusion is a body of igneous rock that has crystallized from a molten magma below the surface of the Earth. Bodies of magma that solidify underground before they reach the surface of the earth are called plutons, named for Pluto, the Roman god of the underworld.
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lithosphere (IPA: [ˈlɪθ.ə.sfiɹ], from the Greek for "rocky" sphere) is the solid outermost shell of a rocky planet. On the Earth, the lithosphere includes the crust and the uppermost mantle which is joined to the crust across the Mohorovičić
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