Figure F23. Comparison of analyses of samples from Hole 1223A with Kilauea-Puna Ridge and Koolau tholeiites plus enriched mid-ocean-ridge basalt (E-MORB) and MORB. A. MgO vs. SiO₂. B. MgO vs. Ba. C. MgO vs. Zr. The general effect of subtraction of olivine with 45% MgO is indicated by the arrow. Symbols distinguish vitric tuffs (red left-pointing triangles) and siltstones (gray triangles). Large open triangles = basaltic glasses from Kilauea and Puna Ridge (Clague et al., 1995); dark green squares = high-MgO basalts from Koolau Volcano, Oahu (Frey et al., 1994); light green right-pointing triangles = E-MORB (data compilation of J. Natland, from several literature sources); small dots = normal mid-ocean-ridge basalt (N-MORB) glasses from the Pacific-Antarctic East Pacific Rise.