In plate tectonics, a convergent boundary – also known as a convergent plate boundary or a destructive plate boundary – is an actively deforming region where two (or more) tectonic plates or fragments of lithosphere move toward one another and collide. Plate tectonics (from Greek τέκτων tektōn "builder" or "mason" describes the large scale motions of Earth 's Lithosphere Plate tectonics (from Greek τέκτων tektōn "builder" or "mason" describes the large scale motions of Earth 's Lithosphere The lithosphere (IPA, from the Greek λίθος for "rocky" + σφαίρα for "sphere" is the solid outermost shell of a rocky Planet.
When two plates move toward one another, they form either a subduction zone or a continental collision. In Geology, a subduction zone is an area on Earth where two tectonic plates meet and move towards one another with one sliding underneath the other Continental collision is a phenomenon of the Plate tectonics of Earth. This depends on the nature of the plates involved. In a subduction zone, the subducting plate, which is normally a plate with oceanic crust, moves beneath the other plate, which can be made of either oceanic or continental crust. During collisions between two continental plates, large mountain ranges, such as the Himalayas are formed.
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Convergent margins
A subduction zone is formed at a convergent plate boundary when one or both of the tectonic plates is composed of oceanic crust. In Geology, a subduction zone is an area on Earth where two tectonic plates meet and move towards one another with one sliding underneath the other Oceanic crust is the part of Earth's Lithosphere that surfaces in the Ocean basins The denser plate, made of oceanic crust, is subducted underneath the less dense plate, which can be either continental or oceanic crust. Oceanic crust is the part of Earth's Lithosphere that surfaces in the Ocean basins When both of the plates are made of oceanic crust, convergence is associated with island arcs such as the Solomon Islands. A volcanic arc is a chain of volcanic islands or Mountains formed by Plate tectonics as an oceanic Tectonic plate subducts under The Solomon Islands is a country in Melanesia, east of Papua New Guinea, consisting of nearly one thousand islands
An oceanic trench is formed where the denser plate is subducted underneath the other plate. The oceanic trenches are hemispheric-scale long but narrow topographic depressions of the sea floor There is water in the rocks that are on the oceanic plate (because they are underwater) and as this plate moves further down into the subduction zone, much of the water contained in the plate is released in dehydration rections. The addition of water to the mantle causes partial melting of the mantle, generating magma, which then rises, and which normally results in volcanoes. This normally happens at a certain depth, about 70 to 80 miles below the earth's surface, and so volcanoes are formed fairly close to, but not right next to the trench.
Some convergent margins have zones of active seafloor spreading behind the island arc, known as back-arc basins. Back-arc basins (or retro-arc basins are geologic features submarine basins associated with Island arcs and Subduction zones.
When one plate is composed of oceanic lithosphere and the other is composed of continental lithosphere, the oceanic plate is subducted, often forming an orogenic belt and associated mountain range. Orogeny (Greek for "mountain generating" is the process of natural Mountain building and may be studied as a tectonic structural event as a geographical event and This type of convergent boundary is similar to the Andes or the Cascade Ranges in North America. The Andes form the world's longest exposed Mountain range. They lie as a continuous chain of highland along the western coast of South America.
When two plates containing continental crust collide, both are too light to subduct. In this case, a continent-continent collision occurs, creating especially large mountain ranges. The most spectacular example of this is the Himalayas.
When the subducting plate approaches the trench obliquely, the convergent plate boundary includes a major component of strike-slip faulting. In Geology a fault, or fault line, is a planar rock fracture which shows evidence of relative movement The best example of this is the Sumatra convergent margin, where convergent action is occurring intermixed with a strike-slip boundary. Sumatra (also spelled Sumatera) is the sixth largest island in the world (approximately 470000 km² and is the largest island entirely in Indonesia (two
Examples
- the collision between the Eurasian Plate and the Indian Plate which is forming the Himalayas. The Eurasian Plate is a Tectonic plate which includes most of the continent of Eurasia (a landmass consisting of the traditional Continents of Europe The India or Indian Plate is a Tectonic plate that was originally a part of the ancient continent of Gondwanaland from which it split off eventually
- subduction of the northern part of the Pacific Plate and the NW North American Plate which is forming the Aleutian Islands. The Pacific Plate is an oceanic Tectonic plate beneath the Pacific Ocean. The North American Plate is a Tectonic plate covering most of North America, Greenland and part of Siberia. The Aleutian Islands (possibly from Chukchi aliat, " Island " are a chain of more than 300 small volcanic islands forming a Volcanic
- subduction of the Nazca Plate beneath the South American Plate to form the Andes Mountains. The Nazca Plate, named after the Nazca region of southern Peru, is an oceanic Tectonic plate in the eastern Pacific Ocean basin off the west The South American Plate is a Tectonic plate covering the Continent of South America and extending eastward to the Mid-Atlantic Ridge. The Andes form the world's longest exposed Mountain range. They lie as a continuous chain of highland along the western coast of South America.
- subduction of the Pacific Plate beneath the Australian Plate, and vice versa, forming the complex New Zealand to New Guinea subduction/transform boundaries. The Pacific Plate is an oceanic Tectonic plate beneath the Pacific Ocean. The Indo-Australian Plate is a major Tectonic plate that includes the continent of Australia and surrounding Ocean, and extends northwest to include the
- collision of the Eurasian Plate and the African Plate formed the Pontic Mountains in Turkey
Other types of plate boundaries
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See also
The Eurasian Plate is a Tectonic plate which includes most of the continent of Eurasia (a landmass consisting of the traditional Continents of Europe The African Plate is a Tectonic plate which includes the Continent of Africa, as well as oceanic crust which lies between the continent and various surrounding In Plate tectonics, a divergent boundary or divergent plate boundary (also known as a constructive boundary or an extensional boundary) is a A transform fault is a fault which runs along the boundary of a Tectonic plate. Plate tectonics (from Greek τέκτων tektōn "builder" or "mason" describes the large scale motions of Earth 's Lithosphere This is a list of tectonic plates on Earth Tectonic plates are pieces of the Earth's crust and uppermost mantle together referred to as the Lithosphere See Plate tectonics for a more complete discussion Tectonic plate interactions are of three different basic types Divergent boundariesDapyx Software network: MP3 Explorer | Ebook Manager | Zenithic