Figure F30. Comparison of analyses of samples from Hole 1223A with Kilauea-Puna Ridge and Koolau tholeiites plus normal and enriched mid-ocean-ridge basalt (MORB and E-MORB, respectively). A. MgO vs. SiO2. B. MgO vs. Ba. C. MgO vs. Zr. The general effect of subtraction of olivine with 45 wt% 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 from Lamont-Doherty Earth Observatory Petrologic Database at www.ldeo.columbia.edu/datarep/index.html and J. Natland, P. Castillo, and Y.-L. Niu, unpubl. data); small dots = normal mid-ocean-ridge basalt (N-MORB) glasses from the Pacific-Antarctic East Pacific Rise.