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A volcanic arc is chain of ) 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 s. Oceans 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. EXAMPLES Continental arcs Island arcs
Ancient Island arcs SEE ALSO REFERENCES
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