Silicon isotopic compositions of altered oceanic crust: Implications for Si isotope heterogeneity in the mantle

The altered oceanic crust recovered from IODP Site 1256, East Pacific Rise has homogeneous δ30Si (− 0.27‰ to − 0.38‰), which is in general agreement with the global fresh MORBs (− 0.27 ± 0.06‰, 2SD; Savage et al., 2014), regardless of the depth and extent of alteration. We also estimated the Si isotope fractionation between the melt and residue minerals of the altered oceanic crust during melting, and the results show that the residual could be enriched in light Si isotopes and the melt could be enriched in heavy Si isotopes.64