Volcanic arc in the context of "Sunda Arc"

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⭐ Core Definition: Volcanic arc

A volcanic arc (also known as a magmatic arc) is a belt of volcanoes formed above a subducting oceanic tectonic plate, with the belt arranged in an arc shape as seen from above. Volcanic arcs typically parallel an oceanic trench, with the arc located further from the subducting plate than the trench. The oceanic plate is saturated with water, mostly in the form of hydrous minerals such as micas, amphiboles, and serpentines. As the oceanic plate is subducted, it is subjected to increasing pressure and temperature with increasing depth. The heat and pressure break down the hydrous minerals in the plate, releasing water into the overlying mantle. Volatiles such as water drastically lower the melting point of the mantle, causing some of the mantle to melt and form magma at depth under the overriding plate. The magma ascends to form an arc of volcanoes parallel to the subduction zone.

Volcanic arcs are distinct from volcanic chains formed over hotspots in the middle of a tectonic plate. Volcanoes often form one after another as the plate moves over the hotspot, and so the volcanoes progress in age from one end of the chain to the other. The Hawaiian Islands form a typical hotspot chain, with the older islands to the northwest and Hawaii Island itself, which is just 400,000 years old, at the southeast end of the chain over the hotspot. Volcanic arcs do not generally exhibit such a simple age-pattern.

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Volcanic arc in the context of South Aegean Volcanic Arc

The South Aegean Volcanic Arc is a volcanic arc in the South Aegean Sea formed by plate tectonics. The prior cause was the subduction of the African plate beneath the Eurasian plate, raising the Aegean arc across what is now the North Aegean Sea. In the Holocene, the process of back-arc extension began, probably stimulated by pressure from the Arabian plate compressing the region behind the arc. The extension deformed the region into its current configuration. First, the arc moved to the south and assumed its arcuate configuration. Second, the Aegean Sea opened behind the arc because the crust was thinned and weakened there. Third, magma broke through the thinned crust to form a second arc composed of a volcanic chain. And finally, the Aegean Sea plate broke away from Eurasia in the new fault zone to the north.

The extension is still ongoing. The current southern Aegean is one of the most rapidly deforming regions of the Himalayan-Alpine mountain belt. It is approximately 450 km long and 20 km to 40 km wide and runs from the Isthmus of Corinth on the Greek mainland to the Bodrum peninsula on the Turkish mainland.

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Volcanic arc in the context of American Cordillera

The American Cordillera (/ˌkɔːrdəlˈjɛrə/ KOR-dəl-YERR) is a chain of mountain ranges (cordilleras), consisting of an almost continuous sequence of mountain ranges that form the western "backbone" of the Americas. Aconcagua is the highest peak of the chain. It is also the backbone of the volcanic arc that forms the eastern half of the Pacific Ring of Fire.

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Volcanic arc in the context of Island arc

Island arcs are long chains of active volcanoes with intense seismic activity found along convergent tectonic plate boundaries. Most island arcs originate on oceanic crust and have resulted from the descent of the lithosphere into the mantle along the subduction zone. They are the principal way by which continental growth is achieved.

Island arcs can either be active or inactive based on their seismicity and presence of volcanoes. Active arcs are ridges of recent volcanoes with an associated deep seismic zone. They also possess a distinct curved form, a chain of active or recently extinct volcanoes, a deep-sea trench, and a large negative Bouguer anomaly on the convex side of the volcanic arc. The small positive gravity anomaly associated with volcanic arcs has been interpreted by many authors as due to the presence of dense volcanic rocks beneath the arc. Inactive arcs are a chain of islands which contains older volcanic and volcaniclastic rocks.

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Volcanic arc in the context of Lesser Antilles

The Lesser Antilles is a group of islands in the Caribbean Sea, forming part of the West Indies in Caribbean region of the Americas. They are distinguished from the larger islands of the Greater Antilles to the west. They form an arc which begins east of Puerto Rico at the archipelago of the Virgin Islands, swings southeast through the Leeward and Windward Islands towards South America, and turns westward through the Leeward Antilles along the Venezuelan coast.

Most of them are part of a long, partially volcanic island arc between the Greater Antilles to the north-west and the continent of South America. The islands of the Lesser Antilles form the eastern boundary of the Caribbean Sea where it meets the Atlantic Ocean. Together, the Lesser Antilles and the Greater Antilles make up the Antilles. The Lesser and Greater Antilles, together with the Lucayan Archipelago, are collectively known as the Caribbean islands or West Indies.

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Volcanic arc in the context of Fore-arc basin

A forearc is a region in a subduction zone between an oceanic trench and the associated volcanic arc. Forearc regions are present along convergent margins and eponymously form 'in front of' the volcanic arcs that are characteristic of convergent plate margins. A back-arc region is the companion region behind the volcanic arc.

Many forearcs have an accretionary wedge which may form a topographic ridge known as an outer arc ridge that parallels the volcanic arc. A forearc basin between the accretionary wedge and the volcanic arc can accumulate thick deposits of sediment, sometimes referred to as an outer arc trough. Due to collisional stresses as one tectonic plate subducts under another, forearc regions are sources for powerful earthquakes.

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Volcanic arc in the context of Central America Volcanic Arc

The Central American Volcanic Arc (often abbreviated to CAVA) 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.

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Volcanic arc in the context of Oceanic trench

Oceanic trenches are prominent, long, narrow topographic depressions of the ocean floor. They are typically 50 to 100 kilometers (30 to 60 mi) wide and 3 to 4 km (1.9 to 2.5 mi) below the level of the surrounding oceanic floor, but can be thousands of kilometers in length. There are about 50,000 km (31,000 mi) of oceanic trenches worldwide, mostly around the Pacific Ocean, but also in the eastern Indian Ocean and a few other locations. The greatest ocean depth measured is in the Challenger Deep of the Mariana Trench, at a depth of 10,994 m (36,070 ft) below sea level.

Oceanic trenches are a feature of the Earth's distinctive plate tectonics. They mark the locations of convergent plate boundaries, along which lithospheric plates move towards each other at rates that vary from a few millimeters to over ten centimeters per year. Oceanic lithosphere moves into trenches at a global rate of about 3 km (1.2 sq mi) per year. A trench marks the position at which the flexed, subducting slab begins to descend beneath another lithospheric slab. Trenches are generally parallel to and about 200 km (120 mi) from a volcanic arc.

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Volcanic arc in the context of Cambrian

The Cambrian ( /ˈkæmbri.ən, ˈkm-/ KAM-bree-ən, KAYM-) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordovician Period 486.85 Ma.

Most of the continents were located in the southern hemisphere surrounded by the vast Panthalassa Ocean. The assembly of Gondwana during the Ediacaran and early Cambrian led to the development of new convergent plate boundaries and continental-margin arc magmatism along its margins that helped drive up global temperatures. Laurentia lay across the equator, separated from Gondwana by the opening Iapetus Ocean.

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Volcanic arc in the context of Lesser Sunda Islands

The Lesser Sunda Islands (Indonesian: Kepulauan Sunda Kecil, Tetum: Illá Sunda ki'ik sirá, Balinese: ᬓᬧᬸᬮᭀᬯᬦ᭄ᬲᬸᬦ᭄ᬤᬘᬾᬦᬶᬓ᭄, romanized: Kapuloan Sunda cénik), now known as Nusa Tenggara Islands (Indonesian: Kepulauan Nusa Tenggara, or "Southeast Islands"), are an archipelago in the Indonesian archipelago. Most of the Lesser Sunda Islands are located within the Wallacea region, except for the Bali province which is west of the Wallace Line and is within the Sunda Shelf. Together with the Greater Sunda Islands to the west, they make up the Sunda Islands. The islands are part of a volcanic arc, the Sunda Arc, formed by subduction along the Sunda Trench in the Java Sea. In 1930 the population was 3,460,059; today over 17 million people live on the islands. Etymologically, Nusa Tenggara means "Southeast Islands" from the words of nusa which means 'island' from Old Javanese language and tenggara means 'southeast'.

The main Lesser Sunda Islands are, from west to east: Bali, Lombok, Sumbawa, Flores, Sumba, Savu, Rote, Timor, Atauro, Alor archipelago, Barat Daya Islands, and Tanimbar Islands. Apart from the eastern half of Timor island and Atauro island which constitute the nation of Timor Leste, all the other islands are part of Indonesia.

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