Additional file 1 of A possible mechanism for spontaneous cyclic back-arc spreading
Creators: name: Ishii, Kazuhiko
name: Wallis, Simon R.
Publisher: name: figshare
Year: 2022
Subjects: subject: Geology
subject: FOS: Earth and related environmental sciences

description: Additional file 1: Figure S1. Effects of changes in the values of the Clapeyron slope. a The change in velocities of the subducting plate (Vsp), the overriding plate (Vop) and the trench (Vtr) combined with the average dip angle of the slab surface (Dip) measured in the depth range of 200–300 km. b Slab geometries. The distribution of effective viscosity is shown by different colors. Blue lines indicate the 410 km and 660 km phase boundaries. Figure S2. Effects of reducing viscosity (a, c) and density (b, d) of the mantle wedge. a Result for a case of AN = 1 × 10-8 /s/MPa for the mantle wedge, otherwise the same conditions as the reference case. b Result for a case where ∆ρ0wedge = 0 kg/m3 for the mantle wedge, otherwise the same conditions as the reference case. c Result for a case where AN =6 × 10-8 /s/MPa for the mantle wedge, otherwise the same conditions as the reference case. d Result for a case where ∆ρ0wedge = 40 kg/m3 for the mantle wedge, otherwise the same conditions as the reference case. Upper panel shows changes in velocities of the subducting plate (Vsp), the overriding plate (Vop) and the trench (Vtr). The average dip angle of the slab surface (Dip) measured in the depth range of 200–300 km is also shown. Lower panel shows the slab geometry. The distribution of effective viscosity is shown by different colors and arrows indicate the velocity field. Figure S3. The effect of changing resolution. a High resolution. b Low resolution. Upper panel shows the change in velocities of the subducting plate (Vsp), the overriding plate (Vop) and the trench (Vtr), in addition to the average dip angle of slab surface (Dip) measured in the depth range of 200–300 km. Lower panels show the distribution of effective viscosity indicated by different colors and the velocity field shown by arrows. Figure S4. Results including pressure-independent density. a Initial distribution of temperature, viscosity and density. b The change in velocities of the subducting plate (Vsp), the overriding plate (Vop) and the trench (Vtr). The average dip angle of slab surface (Dip) measured in the depth range of 200–300 km is also shown. c The distribution of effective viscosity is indicated by different colors and the velocity field is shown by arrows. Figure S5. Result for a case without viscous dissipation until the slab tip reaches a depth of 250 km, otherwise the same conditions as the reference case. a The change in velocities of the subducting plate (Vsp), the overriding plate (Vop) and the trench (Vtr). The average dip angle of slab surface (Dip) measured in the depth range of 200–300 km is also shown. b The distribution of effective viscosity is indicated by different colors and the velocity field is shown by arrows. Figure S6. Result for the case without mantle wedge, otherwise the same conditions as the reference case. a The change in velocities of the subducting plate (Vsp), the overriding plate (Vop) and the trench (Vtr). The average dip angle of slab surface (Dip) measured in the depth range of 200–300 km is also shown. b The distribution of effective viscosity is shown by different colors. Right panels show enlargements of the arc area. Arrows indicate the velocity field. Figure S7. a The slab geometry for the case without a viscosity jump at the 660-km boundary, otherwise the same conditions as the reference case. The distribution of effective viscosity is shown by different colors. b Viscosity distribution. Figure S8. Result for the case without a high effective thermal conductivity for back-arc lithosphere, otherwise the same conditions as the reference case. a Time evolution of slab geometry and velocity field (arrows). The distribution of effective viscosity is shown by different colors. b The changes in velocities of the subducting plate (Vsp), the overriding plate (Vop) and trench (Vtr). Arrows indicate the time for Fig. S8a. Figure S9. Surface heat flow (upper panel) and the distribution of the continental crust (lower panel) at t = 33.6 Myr for the reference case (Fig. 3f).