Active continental margins
Active continental margins occur where a continent sinking oceanic crust. The standard of this geodynamic environment is considered to be the west coast of South America, it is often called the Andean type continental margin. For an active continental margin is characterized by numerous volcanoes, and generally strong magmatism. Melts have three components: oceanic crust, mantle over her and bottoms of the continental crust.
Under the active continental margin is an active mechanical interaction of oceanic and continental plates. Depending on the speed, age and thickness of the oceanic crust are several possible scenarios of equilibrium. If the plate is moving slowly and has a relatively low power, then scouring the continent with its sedimentary cover. Sedimentary rocks are crushed into intensive folds, metamorphosed and become part of the continental crust. Formed in this structure is called the accretionary wedge. If the rate of subducting slab is high and the sediment cover is thin, it erases the bottom of the oceanic crust of the continent and drags him into the mantle.