The vast Cenozoic arc magmatism of Iran introduced three distinct rock series. The LILE (large-ion lithophile elements)-rich and LILE-poor series show signatures of fluid-rich and fluid-poor slab-melt mantle metasomatism, furnished by hot slab subduction. The slab was more hydrated in the northern segment of the study area, where the LILE-rich series dominates. The third series rich in incompatible trace elements, the ITE-rich series, indicates the input of asthenosphere as well.