Figure 6. Selected major-element concentrations of rhyolitic, intermediate, and mafic glass particles recovered at Sites 982 and 985 (lower Pliocene and Miocene sequence) and reference fields for Tertiary Icelandic central volcanoes (· = whole-rock analyses by Walker, 1963, and Carmichael, 1964) and Kolbeinsey Ridge basalts (·· = glass analyses by Lackschewitz and Wallrabe-Adams, 1991, and Lackschewitz et al., 1994). All analyses were normalized to a volatile-free total of 100%. A. TiO₂ vs. K₂O concentrations. B. CaO and TiO₂ vs. MgO concentrations (Site 982). C. CaO and TiO₂ vs. MgO concentrations (Site 985). D. FeO* vs. MgO concentrations.