Oceanic-continental convergent plate boundaries are very similar to oceanic-oceanic boundaries except that one plate is continental. Since oceanic crust has density of 3g/cc and continental crust has a density of only 2.7g/cc whenever oceanic crust collides with continental crust the oceanic crust subducts. Ocean-oceanic convergent plates boundaries form whenever two oceanic plates collide. Since both plates are oceanic subduction will occur causing the older, colder (denser) plate to sink beneath the other. The collision of the plates causes subduction and destruction of the ocean plate. Note the formation of a trench at the plate boundary and a line of volcanoes called an island arc. (Diagram by Phyllis Newbill). In the diagram above, the ocean lithosphere subducts underneath the continental lithosphere. This results in the destruction of the ocean lithosphere and the formation of magmas (with island arc volcanoes above). The deep ocean trench marks the plate boundary and is where the subduction of the ocean lithosphere begins. At these boundaries, two neighboring plates move away from each other. Continental rift valleys are characterized by normal faulting and basalt-rich volcanoes. The diagram shows a typical continental rift. Note the central rift valley that includes From Wikipedia, the free encyclopedia. In plate tectonics, a convergent boundary, also known as a destructive plate boundary (because of subduction), is an actively deforming region where two (or more) tectonic plates or fragments of the lithosphere move toward one another and collide. When one plate is composed of oceanic lithosphere and the other is composed of continental lithosphere, the denser oceanic plate is subducted, often forming an orogenic belt and associated mountain range. This type of convergent boundary is similar to the Andes or the Cascade Range in North America. When a convergent boundary occurs between two oceanic plates one of those plates will subduct beneath the other. Normally the older plate will subduct because of its higher density. The subducting plate is heated as it is forced deeper into the mantle and at a depth of about 100 miles (150 km) the plate begins to melt. Here the Nazca Plate is subducting beneath the South American plate. Visit the Interactive Plate Boundary Map to explore satellite images of convergent boundaries between oceanic and continental plates. Magma rises into and through the other plate, solidifying into new crust. Magma formed from melting plates solidifies into granite, a light colored, low-density rock that makes up the continents. Thus at convergent boundaries, continental crust, made of granite, is created, and oceanic crust is destroyed. Two plates sliding past each other forms a transform plate boundary. Natural or human-made structures that cross a transform boundary are offset—split into pieces and carried in opposite directions Oceanic-Oceanic Plate Convergence. This is similar to oceanic-continental convergence in that one of the plates is subducted under the other during the collision. At the subduction zone a very deep trench is formed in the ocean floor. Oceanic and oceanic plate convergence result in the formation of volcano chains. The crust that is pulled under or subducted melts to form magma. This magma rises to the top of the overriding oceanic plates and erupts on the ocean floor. A subduction zone is formed at a convergent plate boundary when one or both of the tectonic plates is composed of oceanic crust. The denser plate, made of oceanic crust, is subducted underneath the less dense plate, which can be either continental or oceanic crust. When one plate is composed of oceanic lithosphere and the other is composed of continental lithosphere, the denser oceanic plate is subducted, often forming an orogenic belt and associated mountain range. This type of convergent boundary is similar to the Andes or the Cascade Range in North America. The process by which the oceanic crust is pulled under the continental crust is called subduction and the zone at which this occurs at the plate boundaries is called the subduction zone. At the subduction zone where the oceanic crust sinks beneath the continental crust a deep oceanic trench or valley is created. At the subduction zone a very deep trench is formed in the ocean floor. Oceanic and oceanic plate convergence result in the formation of volcano chains. The crust that is pulled under or subducted melts to form magma. This magma rises to the top of the overriding oceanic plates and erupts o As a result of pressure, friction, and plate material melting in the mantle, earthquakes and volcanoes are common near convergent boundaries. When two plates move towards one another, they form either a subduction zone or a continental collision. When one plate is composed of oceanic lithosphere and the other is composed of continental lithosphere, the denser oceanic plate is subducted, often forming an orogenic belt and associated mountain range. This type of convergent boundary is similar to the Andes or the Cascade Range in North America.
http://www.thisoldearth.net/Geology_Online-1_Subchapters.cfm?Chapter=3&Row=5 http://www.radford.edu/jtso/GeologyofVirginia/Tectonics/GeologyOfVATectonics6-2b.html https://en.wikipedia.org/wiki/Convergent_boundary http://geology.com/nsta/convergent-plate-boundaries.shtml http://oceanexplorer.noaa.gov/facts/plate-boundaries.html http://www.passmyexams.co.uk/GCSE/physics/convergent-boundaries.html https://en.wikipedia.org/wiki/Convergent_boundary http://www.passmyexams.co.uk/GCSE/physics/convergent-boundaries.html https://en.wikipedia.org/wiki/Convergent_boundary
convergent plate boundaries oceanic and oceanic diagram