Origin of rear-arc magmatism at Rishiri Volcano

Abstract

The origin of rear-arc magmatism was investigated for basalts from Rishiri volcano. The estimated temperature of the slab surface, from which the fluids were released, was remarkably higher than those predicted by thermal models. This result, along with seismic tomography results, suggest that the magmatism resulted from the production of large amounts of slab fluids, caused by an injection of hot mantle materials into a fracture in the distorted portion of the plate at the arc-arc junction.