Fig. S1. Permian–Triassic felsic tuffs in South Island, New Zealand: significance for oceanic and active continental margin subduction

Major-element oxide variation plots for the Brook Street Terrane. (a) Fe<sub>2</sub>O<sub>3</sub> v. SiO<sub>2</sub>; (b) MnO v. SiO<sub>2</sub>; (c) MgO v. SiO<sub>2</sub>; (d) TiO<sub>2</sub> v. Al<sub>2</sub>O<sub>3</sub>; (e) TiO<sub>2</sub> v. MgO; (f) Fe<sub>2</sub>O<sub>3</sub> v. MgO; (g) MnO v. MgO; (h) CaO v. MgO; (i) K<sub>2</sub>O v. MgO. See text and the Supplementary field and petrographic information for explanation.