Geochemical variation within the northern Ryukyu Arc: Magma source compositions and geodynamic implications

Abstract

The major and trace element and Pb-Sr-Nd isotopic compositions of Quaternary mafic lavas from the northern Ryukyu are provide insights into the nature of the mantle wedge and its tectonic evolution. Beneath the volcanic front in the northern part of the arc, the subducted slab of the Philippine Sea Plate bends sharply and steepens at a depth of ∼80 km. Lavas from the volcanic front have high abundance of large ion lithophile elements and light rare earth elements relative to the high field strength elements, consistent with the result of fluid enrichment processes related to dehydration of the subducting slab. New Pb isotopic data identify two distinct asthenospheric domains in the mantle we..