Effects of temporal plume–slab interaction on the partial melting of the subducted oceanic crust

Abstract

The plume–slab interaction facilitates the partial melting of the subducted oceanic crust in subduction zones and explains the pulse-like adakite eruptions in the Abukuma region, northeastern Japan from approximately 16 to 14Ma, as well as the southwest-to-northeast migration of the adakite eruptions from southeastern China to southwestern Japan during the Cretaceous. Despite the potential implication of the plume–slab interaction to arc magmatism, the effects of the plume parameters on the partial melting of the subducted oceanic crust have not been quantitatively evaluated. Thus, we ran two-dimensional kinematic–dynamic numerical subduction experiments to evaluate the effect of the duration and thickness of the injected plume blob into the mantle wedge on the slab surface temperature. Along with the consideration of the injection of the plume blob, we consider diverse convergence rates and ages of the subducting slab with slab dips of 30° and 45°. Our model calculations show that the plume–slab interaction is a promising process that increases the slab surface temperature up to around 60°C, resulting in the partial melting of the subducted oceanic crust even though the plate age is 100My (million years). Increases in the duration and thickness of the plume blob positively increase the peak temperatures of the slab surface. Increases in the convergence rate and age of the subducting slab almost systematically increase and decrease the slab surface temperature, respectively, which indicates that the net temperature contribution of the plume–slab interaction is similar regardless of the subduction parameters. We found that the contribution of time-evolving subduction parameters on the plume–slab interaction can be approximated using the subduction parameters of approximately 5My before the time of the partial melting of the subducted oceanic crust. Our model calculations facilitate the first-order analysis of the plume–slab interaction in the subduction zones of which subduction parameters are not consistent with the observed adakite.