Convergent boundary

Convergent boundaries are areas on Earth where two or more lithospheric plates collide. One plate eventually slides beneath the other causing a process known as subduction. The subduction zone can be defined by a plane where many earthquakes occur, called the Benioff Zone[1]. These collisions happen on scales of millions to tens of millions of years and can lead to volcanism, earthquakes, orogenesis, destruction of lithosphere, and deformation. Convergent boundaries occur between oceanic-oceanic lithosphere, oceanic-continental lithosphere, and continental-continental lithosphere. The geologic features related to convergent boundaries vary depending on crust types.

Plate tectonics is driven by convection cells in the mantle. Convection cells are the result of heat generated by radioactive decay of elements in the mantle escaping to the surface and the return of cool materials from the surface to the mantle[2]. These convection cells bring hot mantle material to the surface along spreading centers creating new crust. As this new crust is pushed away from the spreading center by formation of newer crust, it cools, thins, and becomes denser. Subduction initiates when this dense crust converges with less dense crust. The force of gravity helps drive the subducting slab into the mantle. Evidence supports that the force of gravity will increase plate velocity[3]. As the relatively cool subducting slab sinks deeper into the mantle, it is heated causing dehydration of hydrous minerals. This releases water into the hotter asthenosphere, which leads to partial melting of asthenosphere and volcanism. Both dehydration and partial melting occurs along the 1000°C isotherm, generally at depths of 65 - 130 km[4][5].

Simplified schematic of different convergent boundary types.

Some lithospheric plates consist of both continental and oceanic lithosphere. In some instances, initial convergence with another plate will destroy oceanic lithosphere, leading to convergence of two continental plates. Neither continental plate will subduct. It is likely that the plate may break along the boundary of continental and oceanic crust. Seismic tomography reveals pieces of lithosphere that have broken off during convergence.

Subduction zones

Subduction zones are areas where one lithospheric plate slides beneath another at a convergent boundary due to lithospheric density differences. These plates dip at an average of 45° but can vary. Subduction zones are often marked by an abundance of earthquakes, the result of internal deformation of the plate, convergence with the opposing plate, and bending at the oceanic trench. Earthquakes have been detected to a depth of 670 km. The relatively cold and dense subducting plates are pulled into mantle and help drive mantle convection[6].

Other Languages
العربية: حدود متقاربة
čeština: Aktivní okraj
فارسی: مرز همگرا
한국어: 수렴 경계
Bahasa Indonesia: Batas konvergen
íslenska: Flekamót
Kreyòl ayisyen: Limit konvèjan
日本語: 収束型境界
português: Limite convergente
Simple English: Convergent boundary
slovenčina: Aktívny okraj
srpskohrvatski / српскохрватски: Konvergentna granica
Tiếng Việt: Ranh giới hội tụ