Figure F59. FeO vs. MgO whole-rock concentrations in Site 1271 peridotites. Published data are also shown for comparison: open diamonds = Mid-Atlantic Ridge peridotites from Leg 109, Site 670 (Hebert at al., 1990) and Leg 153 Site 920 (Casey, 1997). Other symbols are: * = Southwest Indian Ridge (Snow and Dick, 1995), + = Izu-Bonin-Mariana forearc (Parkinson and Pearce, 1998), gray diamond = East Pacific Rise peridotites (Niu and Hekinian, 1997), x = Western Alps orogenic lherzolites and ophiolites (Bodinier, 1988; Rampone et al., 1996), gray circle = Oman ophiolite harzburgites (Godard et al., 2000), gray triangle = Oman ophiolite mantle transition zone dunites (Godard et al., 2000). Whole-rock compositions are presented on a volatile-free basis assuming all Fe is FeO. The solid black lines show olivine and orthopyroxene composition as a function of Fe/Mg. Fine gray lines show constant Mg# values (Mg# = 100 x Mg/[Mg + Fetotal]). Fetotal = total Fe as FeO.