High-temperature properties of silicate liquids: applications to the equilibration and ascent of basic magma (original) (raw)

1977, Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences

High-temperature heat content measurements have been made on a series of silicate liquids, which in conjunction with published data, are used to derive partial molar heat capacities of SiO 2 , TiO 2 , Al 2 O 3 , Fe 2 O 3 , FeO, MgO, CaO, Na 2 O and K 2 O in the temperature range 1200-1650 K. Only Fe 2 O 3 appears to be compositionally dependent, and the best evidence suggests that there is no excess heat capacity (CPi i = C°). In combination with calorimetric data and the effect of pressure on the fusion temperature of solid compounds, a consistent set of enthalpy, entropy and volume data have been derived for the liquid compounds CaMgSi 2 O 6 , NaAlSi 3 O 8 , KAlSi 3 O 8 , Fe 2 SiO 4 and TiO 2 . By using activities (relative to a liquid standard state) calculated at 1 bar for a range of lavas, the equilibration pressures and temperatures of lavas with a lherzolitic source material are calculated, and for basanites indicate 22-26 kbar and 1310-1360 °G. The regular solution formulati...