Figure 7. SiO2 vs. Al2O3, CaO, FeO*, CaO/Al2O3, TiO2, and V. Major-element data were normalized to 100% on a volatile-free basis, assuming that CO2 comes from CaCO3. Rhyolite sample 7647-I (161-978A-47R-1, 0-6 cm) was omitted from the diagram, because of its high CO2 (9.9 wt%) content and thus causing a problem with the CaO correction. Dashed fields enclose data with H2O

Figure 7. SiO₂ vs. Al₂O₃, CaO, FeO*, CaO/Al₂O₃, TiO₂, and V. Major-element data were normalized to 100% on a volatile-free basis, assuming that CO₂ comes from CaCO₃. Rhyolite sample 7647-I (161-978A-47R-1, 0-6 cm) was omitted from the diagram, because of its high CO₂(9.9 wt%) content and thus causing a problem with the CaO correction. Dashed fields enclose data with H₂O < 4 wt%, except when sample name is noted.