A quantitative framework for global variations in arc geochemistry

Arc magmas are generated by partial melting of a mantle wedge modified inputs from subducting sediment and igneous ocean crust. Despite this uniform tectonic process, global arc-front stratovolcano compositions exhibit trace element abundances that can vary more than an order magnitude. All incompatible elements correlate well, including those thought to be derived, “fluid-mobile”, derived. It has been suggested variations in arc occur due the addition variable slab components depleted wedge, though quantitative models include both isotopes have lacking. Here we present alternative framework which relatively constant proportion material, consisting melts altered crust sediment, is added ambient varies MORB as enriched “EM1” island basalt sources. The varying extents, with controlled primarily thickness overlying lithosphere. Thick lithosphere leads lower extents garnet stability field most continental arcs. Continental arcs also mantle, likely because contributions sub-continental lithospheric mantle. High degrees sources cause oceanic low abundances. Quantitative modeling these processes shows account for systematics exhibited stratovolcanoes provides tool examine regional unusual magma compositions. Variations temperature amount input remain important second-order certain ratios.