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island arc |
Also found in: Dictionary/thesaurus, Wikipedia, Hutchinson | 0.09 sec. |
island arcLong, curved chain of oceanic islands associated with intense volcanic and seismic activity and mountain-building processes. Examples include the Aleutian-Alaska Arc and the Kuril-Kamchatka Arc. Most island arcs consist of two parallel rows of islands. The inner row is a string of volcanoes, and the outer row is made up of nonvolcanic islands. In the case of single arcs, many of the islands are volcanically active. An island arc typically has a landmass or a partially enclosed, unusually shallow sea on its concave side. Along the convex side there usually exists a long, narrow deep-sea trench. How to thank TFD for its existence? Tell a friend about us, add a link to this page, add the site to iGoogle, or visit webmaster's page for free fun content. |
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Such basins are generally nestled behind volcanic arcs, on the overriding plate of a subduction zone. The license area contains arc-magmatic rocks of Tertiary age, largely consisting of grano-dioritic intrusives and related porphyric andesites, typical of volcanic arc environments, where epithermal gold-silver mineralization can be expected. It is located in the active Halmahera volcanic arc and the mineralization is hosted by a potassic altered and magnetite bearing tonalite porphyry stock. |
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