Arc magmas sourced from mélange diapirs in subduction zones

At subduction zones, crustal material is recycled back into the mantle. A certain proportion, however, is returned to the overriding plate via magmatism. The magmas show a characteristic range of compositions that have been explained by three-component mixing in their source regions: hydrous fluids derived from subducted altered oceanic crust and components derived from the thin sedimentary veneer are added to the depleted peridotite in the mantle beneath the volcanoes. However, currently no uniformly accepted model exists for the physical mechanism that mixes the three components and transports them from the slab to the