What is the origin of the magmas that form at a convergent plate boundary? ?

Question

Answer doesnt have to be lengthy.

Answer 1

The remelting of crustal material forced down under the edge of the continental crust. The steeply plunging layer can be traced seismically (the Benioff Zone). As the crustal layer tends to be less dense than the mantle it is being pushed down into, remelted material tends to rise toward the surface