Island arc in the context of "Convergent boundary"

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⭐ Core Definition: 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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Island arc in the context of Japanese archipelago

The Japanese archipelago (Japanese: 日本列島, Hepburn: Nippon/Nihon Rettō; Japanese pronunciation: [ɲip.pon/ɲi.hon ɾeꜜt.toː]) is an archipelago of 14,125 islands that form the country of Japan. It extends over 3,000 km (1,900 mi) from the Sea of Okhotsk in the northeast to the East China and Philippine seas in the southwest along the Pacific coast of the Eurasian continent, and consists of three island arcs from north to south: the Northeastern Japan Arc, the Southwestern Japan Arc, and the Ryukyu Island Arc. The Daitō Islands, the Izu–Bonin–Mariana Arc, and the Kuril Islands neighbor the archipelago.

Japan is the largest island country in East Asia and the fourth-largest island country in the world with 377,975.24 km (145,937.06 sq mi). It has an exclusive economic zone of 4,470,000 km (1,730,000 sq mi).

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Island arc in the context of North Asia

North Asia or Northern Asia (Russian: Северная Азия) is the northern region of Asia, which is defined in geographical terms and consists of three federal districts of Russia: Ural, Siberian, and the Far Eastern. North Asia is bordered by the Arctic Ocean to its north; by Eastern Europe to its west; by Central Asia and East Asia to its south; and by the Pacific Ocean and Northern America to its east. It covers an area of 13,100,000 square kilometres (5,100,000 sq mi), or 8.8% of Earth's total land area; and is the largest subregion of Asia by area, occupying approx. 29.4% of Asia's land area, but is also the least populated, with a population of around 37 million, accounting for merely 0.74% of Asia's population.

Topographically, the region is dominated by the Eurasian Plate, except for its eastern part, which lies on the North American, Amurian, and Okhotsk Plates. It is divided by three major plains: the West Siberian Plain, Central Siberian Plateau, and Verhoyansk-Chukotka collision zone. The Uralian orogeny in the west raised Ural Mountains, the informal boundary between Asia and Europe. Tectonic and volcanic activities are frequently occurred in the eastern part of the region as part of the Ring of Fire, evidenced by the formation of island arcs such as the Kuril Islands and ultra-prominent peaks such as Klyuchevskaya Sopka, Kronotsky, and Koryaksky. The central part of North Asia is a large igneous province called the Siberian Traps, formed by a massive eruption which occurred 250 million years ago. The formation of the traps coincided with the Permian–Triassic extinction event.

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Island arc in the context of Northeastern Japan Arc

The Northeastern Japan Arc, also Northeastern Honshū Arc, is an island arc on the Pacific Ring of Fire. The arc runs north to south along the Tōhoku region of Honshū, Japan. It is the result of the subduction of the Pacific plate underneath the Okhotsk plate at the Japan Trench. The southern end of the arc converges with the Southwestern Japan Arc and the Izu–Bonin–Mariana Arc at the Fossa Magna (ja) at the east end of the Itoigawa-Shizuoka Tectonic Line (ITIL). This is the geologic border between eastern and western Honshū. Mount Fuji is at the point where these three arcs meet. To the north, the Northeastern Japan arc extends through the Oshima Peninsula of Hokkaidō. The arc converges in a collision zone with the Sakhalin Island Arc and the Kuril Island Arc in the volcanic Ishikari Mountains of central Hokkaidō. This collision formed the Teshio and Yūbari Mountains.

The Ōu Mountains form the backbone of the volcanic part of the inner arc that run from Natsudomari Peninsula in Aomori Prefecture south to Mount Nikkō-Shirane in Tochigi and Gunma prefectures. The volcanic front consists of four north to south lines of Quaternary volcanoes and calderas, which extend the length of the range. It also includes the Quaternary volcanoes of southwestern Hokkaido. The Dewa Mountains and the Iide Mountains are non-volcanic uplift ranges that run parallel to the west of the Ōu Mountains.

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Island 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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Island arc in the context of Andesite

Andesite (/ˈændəzt/) is a volcanic rock of intermediate composition. In a general sense, it is the intermediate type between silica-poor basalt and silica-rich rhyolite. It is fine-grained (aphanitic) to porphyritic in texture, and is composed predominantly of sodium-rich plagioclase plus pyroxene or hornblende.

Andesite is the extrusive equivalent of plutonic diorite. Characteristic of subduction zones, andesite represents the dominant rock type in island arcs. The average composition of the continental crust is andesitic. Along with basalts, andesites are a component of the Martian crust.

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Island arc in the context of Kuril–Kamchatka Trench

The Kuril–Kamchatka Trench or Kuril Trench (Russian: Курило-Камчатский жёлоб, Kurilo-Kamchatskii Zhyolob) is an oceanic trench in the northwest Pacific Ocean. It lies off the southeast coast of Kamchatka and parallels the Kuril Island chain to meet the Japan Trench east of Hokkaido. It extends from a triple junction with the Ulakhan Fault and the Aleutian Trench near the Commander Islands, Russia, in the northeast, to the intersection with the Japan Trench in the southwest.

The trench formed as a result of the subduction zone, which formed in the late Cretaceous, that created the Kuril island arc as well as the Kamchatka volcanic arc. The Pacific plate is being subducted beneath the Okhotsk plate along the trench, resulting in intense volcanism.

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Island arc in the context of Leeward Antilles

The Leeward Antilles (Dutch: Benedenwindse Eilanden; Spanish: islas de Sotavento) are a chain of islands in the Caribbean, specifically part of the southerly islands of the Lesser Antilles (and, in turn, the Antilles and the West Indies) along the southeastern fringe of the Caribbean Sea, just north of the Venezuelan coast of the South American mainland. The Leeward Antilles, while among the Lesser Antilles, are not to be confused with the Leeward Islands (also of the Lesser Antilles) to the northeast.

Largely lacking in volcanic activity, the Leeward Antilles island arc occurs along the deformed southern edge of the Caribbean Plate and was formed by the plate's subduction under the South American Plate. Recent studies indicate that the Leeward Antilles are accreting to South America.

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Island arc in the context of Burma plate

The Burma plate is a minor tectonic plate or microplate located in Southeast Asia, sometimes considered a part of the larger Eurasian plate. The Andaman Islands, Nicobar Islands, and northwestern Sumatra are located on the plate. This island arc separates the Andaman Sea from the main Indian Ocean to the west.

To its east lies the Sunda plate, from which it is separated along a transform boundary, running in a rough north–south line through the Andaman Sea. This boundary between the Burma and Sunda plates is a marginal seafloor spreading centre, which has led to the opening up of the Andaman Sea (from a southerly direction) by "pushing out" the Andaman-Nicobar-Sumatra island arc from mainland Asia, a process which began in earnest approximately 4 million years ago.

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