Fig. 7
From: Sulfide resorption during crustal ascent and degassing of oceanic plateau basalts
Primitive mantle-normalized PGE and CSE abundances of primitive OPB, MORB and komatiites. The CSE patterns of primitive OPB (Kroenke; blue line) and parental-MORB (orange line) are similar for Ag, Cu, Se, S and Bi. Together with their chondritic S/Se, this suggests that sulfide was exhausted from both the MORB-and OPB-source mantle and that melting terminated close to the point of sulfide-exhaustion. By contrast, komatiites are offset to lower primitive mantle-normalized Pt, Pd and Cu. Given that komatiites are generated by significantly high degrees of partial melting54, these offsets suggest that the [CSE] of komatiites were diluted by continued melting in the absence of residual sulfide. Assuming that the CSE behaved perfectly incompatible after sulfide-exhaustion, estimates of the mantle source composition of OPB and MORB (dashed lines) are derived by assuming 30% and 20% degree of melting, respectively. The OPB mantle source estimate is well-matched to the primitive mantle estimates of McDonough and Sun15, supporting our interpretation that sulfide was exhausted from the OPB mantle source. PGE data for OPB and MORB are taken from Chazey and Neal31 and the compilation of Barnes et al.46, respectively. Parental-MORB CSE estimates are taken from Jenner1, except for Se, which is calculated from new MORB data presented in this study. PGE and Cu data for komatiites is taken from Puchtel and Humayan54. Sulfide-silicate partition coefficients are taken from Mungall and Brenan53 (Pt, Pd and Au) and Patten et al.6 (Re, Ag, Cu, Se and Bi). Data are normalized to the primitive mantle estimates of Palme and O’Neill13
