Experimental synthesis of Fe-bearing olivine at near-solidus temperatures and its decomposition during longtime heating

Several investigations have demonstrated that olivine may be used to simulate geochemical and cosmochemical reactions. Since olivine in extra-terrestrial samples has varying forsterite numbers and natural olivine contains inevitable impurities, synthetic olivine with the requisite forsterite number has been prepared for various experimental research. This study aimed to synthesize Fe-bearing olivine via synthetic experiments conducted at near-solidus temperatures and elucidate the formation and decomposition mechanisms of the obtained Fe-bearing olivine. Specifically, we attempted to synthesize Fo60 (Forsterite number = 100 × Mg/(Mg + Fe) = 60) olivine using a mixture of analytical-grade SiO2, MgO, and Fe2O3. To clarify the stability of the obtained olivine, the temperature range (1350–1500 °C) and heating durations (1.5 h or 15 h) were controlled under a constant oxygen fugacity of QFM-1 log units.