Along-strike island arc magma production rates of the Tonga-Kermadec subduction zone

Island arc magmatism is a key process of subduction systems, providing insights into subduction dynamics. The Tonga-Kermadec subduction zone offers an ideal environment for studying arc magmatism. However, the variations in the island arc magmatic production rate (MPR) along the arc and how the factors influencing these variations remain poorly understood. This study uses gravity inversion methods to estimate MPR variations along the Tonga-Kermadec subduction zone, considering both active and remnant arcs, and numerical simulations to investigate the mechanisms behind the influencing factors on island arc magmatism. Our findings show that: (1) The magma production rate shows an overall increasing trend from south to north. The correlation between convergence rate and arc MPR is higher than that between subducting plate age and island arc MPR. (2) A higher convergence rate enhances MPR by strengthening mantle convection and increasing water flux into the mantle wedge; MPR increases and then decreases with slab dip angle, peaking at 45°, mainly driven by water content rather than temperature; An older slab reduces MPR by lowering mantle wedge temperature and water content.