Granodiorite, like diorite, is the result of fractional melting of a mafic parent rock above a subduction zone. It is commonly produced in volcanic arcs, and in cordilleran mountain building (subduction along the edge of a continent, such as with the Andes Mountains). It emplaces in large batholiths (many thousands of square miles) and sends magma to the surface to produce composite volcanoes with andesite lavas.