Figure F23. TiO2 vs. Mg# diagram for basalt and volcaniclastic rocks. Basalt from Site 1187 is distinct from that of the Kwaimbaita and Singgalo Formations of Malaita (Tejada et al., in press) and from that recovered during Leg 130 at Sites 803 and 807 (Mahoney et al., 1993). The high Mg# and low TiO2 contents of the Site 1187 basalt units show their relatively primitive nature and demonstrate the compositional similarity to the upper group of basaltic units at Site 1185. Mg# is calculated assuming that 12% of the iron is Fe3+, which is equivalent to Fe2O3/(Fe2O3+FeO) = 0.13, or Fe2O3/FeO = 0.15.

Figure F23. TiO₂ vs. Mg# diagram for basalt and volcaniclastic rocks. Basalt from Site 1187 is distinct from that of the Kwaimbaita and Singgalo Formations of Malaita (Tejada et al., in press) and from that recovered during Leg 130 at Sites 803 and 807 (Mahoney et al., 1993). The high Mg# and low TiO₂ contents of the Site 1187 basalt units show their relatively primitive nature and demonstrate the compositional similarity to the upper group of basaltic units at Site 1185. Mg# is calculated assuming that 12% of the iron is Fe³⁺, which is equivalent to Fe₂O₃/(Fe₂O₃+FeO) = 0.13, or Fe₂O₃/FeO = 0.15.