Continental arc

A continental arc is a type of volcanic arc occurring as an "arc-shape" topographic high region along a continental margin. The continental arc is formed at an active continental margin where two tectonic plates meet and a subduction zone develops. The magmatism and petrogenesis of continental crust are complicated: in essence, continental arcs reflect a mixture of oceanic crust materials, mantle wedge and continental crust materials.

When two tectonic plates collide, relatively denser oceanic crust will be subducted under relatively lighter continental crust. Because of the subduction process, the relatively cooler oceanic crust, along with water, is subducted to the asthenosphere, where pressures and temperatures are much higher than the surface of earth. Under such conditions, the downgoing plate releases volatiles such as H₂O and CO₂, which cause partial melting of the above asthenosphere. This process can create relatively buoyant magma, which subsequently forms a series of volcanoes at the surface along the subduction zone. There are some researchers who argue that refertilization of arc lithospheric mantle may also be an important process associated with arc magmatism. Because the subduction zone (which is also the plate boundary) is generally an arc-shape, geologists named those volcanoes volcanic arcs. A volcanic arc built on continental crust is called a continental arc; when built on oceanic crust the volcanoes form an island arc.

...
Wikipedia