Where the crust is heated, thermal expansion causes the rocks to become lighter and more buoyant. Both plates are oceanic crust Because both plates are basaltic, most volcanism is basaltic Initially results in an island chain, but long-continued subduction and accumulation of volcanic rocks and sediments can create a substantial land mass. Ocean-Continent Descending plate is oceanic crust, overriding plate is a continent. Often continent-ocean subduction will bring a continent into contact with an island arc or small continental fragment. This happens to most orogenic belts eventually.
Result is many fault-bounded regions sharply different from adjacent rocks.
Result is an orogenic belt in the middle of a continent. The two sides of the orogenic belt are separated by a suture marked by blueschist metamorphism, melange, ophiolites and major faults. The rocks on either side of the suture may show quite different histories. We can divide an orogenic belt into parallel zones defined by their deformation, lithology, or metamorphism. These zones may approximately coincide with each other but somewhat overlap, so it's necessary to have distinct names for them.