Supplementary Data: SD1: Sample source, stratigraphical unit, location, age, TAS ID and type. SD2: Major oxide compositions, weight loss on ignition (LOI), and minor and trace element concentrations of the lavas of Taranaki from this study. SD3: Major oxide concentrations of samples from Taranaki from literature (Price et al. 1992, 1999; Stewart et al. 1996; R. B. Stewart pers. comm. 2018; Zernack et al. 2012). SD4: Minor and trace element concentrations of samples from Taranaki from literature (Price et al. 1992, 1999; Stewart et al. 1996; R. B. Stewart pers. comm. 2018; Zernack et al. 2012). SD5: EPMA spot analyses of mineral crystals from this study. SD6: Major oxide concentrations of groundmass of lavas of Taranaki, measured through defocussed EPMA beam. Average of 30 spot analyses used. SD7: Modal proportions of mineral phases, groundmass, and vesicles of lavas of Taranaki. SD8: Accuracy and precision for all analyses.