Fig. 2: Erupted liquid compositions from the Galápagos Archipelago.

TiO₂ vs. Mg#_liq of erupted liquids at a Wolf volcano and b Fernandina. The points show: whole-rock, tephra glass, submarine glass and melt inclusion literature data from all volcanoes in the western Galápagos Archipelago (excluding intrusive rocks and plagioclase-ultraphyric lavas); historic erupted liquids (i.e. whole-rocks, tephra glasses and submarine glasses) from Wolf and Fernandina; and whole-rock and tephra glass data from the 2015 Wolf and 1968 Fernandina eruptions (see legend). References for Wolf and Fernandina historic erupted liquids and literature data from all western Galápagos volcanoes are in Supplementary Note 2. Glass data for the 2015 Wolf eruption are from Stock et al.¹⁹ and whole-rock data are from this study. Glass and whole-rock data for the 1968 Fernandina eruption are from Allan and Simkin²⁸. Characteristic 2σ analytical uncertainties for our whole-rock analyses are less than the size of a data point. The black lines show liquid lines of descent calculated using Rhyolite-MELTS at 50 MPa (solid line), 300 MPa (dashed line) and 500 MPa (dotted line). The kernel density estimates above each panel show the Mg#_liq distribution of the historic erupted liquids from Wolf and Fernandina, the red points show their median Mg#_liq, and the red bars show their Mg#_liq interquartile range. The grey dotted bars above each panel show the Mg#_liq interquartile range of historic lavas from Santiago²⁶ (centred around the Wolf and Fernandina medians) for comparison.