Figure 3
Geochemical characteristics of mafic and ultramafic rocks from diamond-bearing ophiolites plotted against fields of tectonic settings. (a) Nb/Yb versus TiO2/Yb in mafic rocks, (b) Al2O3 versus FeOt (in wt. %) in mantle rocks. See Supplementary Data Figure S2 for definition and sources of the tectonic setting discrimination fields. Also shown in (a) are the oceanic basalt (MORB) and ocean island basalt (OIB) discriminant fields (arrays) of Pearce67, and in (b) the experimental melting residue for polybaric fractional melting of fertile mantle68, with faded color shades showing data affected by subduction-related metasomatism69. Dotted ovals show fields of tectonic settings following the same color code as in (a).
