Iron-magnesium-silicate perovskite was melted in a laser-heated diamon
d anvil cell and monitored by thermal analysis. Two signals were ident
ified at each pressure: a lower temperature signal and a higher temper
ature signal. The lower signal may correspond to the temperature where
iron diffuses rapidly. The higher signal would then correspond to mel
ting of magnesium-enriched silicate perovskite. Alternatively, the low
er signal may be the solidus where (Fe.14Mg.86)SiO3 undergoes incongru
ent melting to an iron-magnesium-enriched solid plus a silica-enriched
liquid. Then, the higher signal would be the liquidus. The slope for
the melting curve (the higher signal) between 30GPa and 94GPa is sligh
tly negative. Fitting to a straight line gives a value for the slope o
f -2.5 +/- 0.6K/Gpa. At 30GPa, the lower signal is almost-equal-to 300
K below the melting curve. They converge slightly at higher pressures
and differ by almost-equal-to 140K at 94GPa. Our melting curve is seve
ral hundred degrees (K) below previous estimates.