The melting relations in fayalite Fe
2SiO
4 and its high pressure modification γ-Fe
2SiO
4 have been experimentally studied at pressures up to about 200kbar. Fayalite melts congruently up to the triple point, 70±5kbar and 1, 520±25°C, of fayalite, γ-Fe
2SiO
4, and liquid. The initial slope of γ-Fe2siO4 is about 12°/kbar. γ-Fe
2siO
4 melts congruently up to about 130 kbar, above which it melts incongruently into stishovite SiO2 and liquid. The incongruent melting in γ-Fe
2SiO
4 terminates at about 170kbar and 2, 200°C. Above this pressure, the melting mode switches to the eutectic melting between wustite Fe
1-xO and stishovite SiO
2, which are the post γ-Fe
2SiO
4 assembly. The present data suggest a possibility of incongruent melting of γ-(Mg, Fe)
2SiO
4 at high pressure. Possible roles of the change in melting mode on the chemical fractionation of the earth's mantle are discussed.
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