In collisions between two oceanic plates, the cooler, denser oceanic lithosphere sinks beneath the warmer, less dense oceanic lithosphere. The relatively cold and dense subducting plates are pulled into the mantle and help drive mantle convection. Earthquakes have been detected to a depth of 670 km (416 mi). 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. These plates dip at an average of 45° but can vary. Subduction zones are areas where one lithospheric plate slides beneath another at a convergent boundary due to lithospheric density differences.

4 Continental – continental convergence.

Seismic tomography reveals pieces of lithosphere that have broken off during convergence. It is likely that the plate may break along the boundary of continental and oceanic crust. In some instances, initial convergence with another plate will destroy oceanic lithosphere, leading to convergence of two continental plates. Some lithospheric plates consist of both continental and oceanic lithosphere. Both dehydration and partial melting occurs along the Template:Cvt isotherm, generally at depths of Template:Cvt. This releases water into the hotter asthenosphere, which leads to partial melting of asthenosphere and volcanism. As the relatively cool subducting slab sinks deeper into the mantle, it is heated, causing hydrous minerals to break down.

The force of gravity helps drive the subducting slab into the mantle. Subduction begins when this dense crust converges with less dense crust. As this new crust is pushed away from the spreading center by the formation of newer crust, it cools, thins, and becomes denser. These convection cells bring hot mantle material to the surface along spreading centers creating new crust. 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. Plate tectonics is driven by convection cells in the mantle. The geologic features related to convergent boundaries vary depending on crust types. Convergent boundaries occur between oceanic-oceanic lithosphere, oceanic-continental lithosphere, and continental-continental lithosphere.

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. The subduction zone can be defined by a plane where many earthquakes occur, called the Wadati–Benioff zone. One plate eventually slides beneath the other, a process known as subduction. Simplified diagram of a convergent boundaryĪ convergent boundary (also known as a destructive boundary) is an area on Earth where two or more lithospheric plates collide. So.Template:Short description File:Continental-continental destructive plate boundary.svg I also heard that this is an area of ongoing research and it isn't fully understood what happens at cc convergent boundaries. Apparently rockes which where once part of the continental plate melt and resurface. Either no subduction of the continental plate occurs or the continental plate is subducted and melts somewhere around 90 to 140 km down.

What exactly happens at a continental-continental (cc) convergent boundary? I read myself through the web for the last few days and what I came up with is that such a boundary will start as an oceanic-continental (oc) one until the continental plates meet and then a huge falt mountain range like the Himalaja, Alps or Appalacian Mountains is formed.Īt this point the sources I found gave me conflicting information.

Convergent boundary