Fig. 4

Temperature conditions and SiO₂ contents of hydrous melt in equilibrium with amphibole phenocrysts, as estimated using the methods of Putirka (2016). Diamonds and circles indicate amphibole phenocrysts in samples 4I-1w and 4I-1p, respectively. Error bars indicate 1σ errors for estimations of temperature (±30 °C) and \({\text{SiO}}_{2}^{\text{melt}}\) (± 3 wt%). Gray area shows the T–\({\text{SiO}}_{2}^{\text{melt}}\) conditions of the groundmass melt of the 4I-1 magma; the temperature is based on Fe–Ti oxide thermometry (from Kaneko et al. 2007). The double-headed arrow indicates the range estimated using two-pyroxene thermometry (from Kaneko et al. 2007)