57Fe Mössbauer spectroscopy of mineral assemblages in mantle spinel lherzolites from Cenozoic alkali basalt, eastern China: Petrological applications

Mineral assemblages in spinel lherzolite xenoliths from the Cenozoic alkali basalt of eastern China were analyzed by 57Fe Mössbauer spectroscopy for Fe3+/ΣFe and distribution of Fe2+/Fe3+ in non-equivalent crystal cites. Orthopyroxene, clinopyroxene and spinel have 0.08–0.13, 0.19–0.31 and 0.13–0.23 Fe3+/ΣFe, respectively. The cation-exchange equilibrium temperatures, Fe3+ partition coefficient and oxygen fugacity of the upper mantle peridotites were calculated. The equilibrium temperatures are between 1103 K and 1405 K consistent with those reported elsewhere. The oxygen fugacities of spinel lherzolites calculated with olivine–orthopyroxene–spinel (ΔlogƒO2 from − 1.1 to 0) and clinopyroxene–olivine–orthopyroxene oxybarometers (ΔlogƒO2 from − 2.0 to 0.7) are consistent with previously reported upper mantle values.

► Mineral assemblages were analyzed by 57Fe Mössbauer spectroscope. ► Fe3+/ΣFe in spinel and clinopyroxene are positively related to the oxygen fugacity. ► The valence distribution of iron majorly influenced the oxygen fugacity.