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Revised and supplemented data on Gibbs' free energies of substances at the parameters of the Earth's mantle
Author(s) -
Ostrovsky I. A.
Publication year - 1989
Publication title -
geological journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.721
H-Index - 54
eISSN - 1099-1034
pISSN - 0072-1050
DOI - 10.1002/gj.3350240202
Subject(s) - mantle (geology) , methane , metastability , geology , mineralogy , pyrrhotite , gibbs free energy , carbonate , thermodynamics , geochemistry , chemistry , physics , organic chemistry , pyrite
New (revised) data on thermodynamic properties of 60 substances are calculated by extrapolating their compressibilities and calorific properties up to 4000 K and 1 Mbar. Stability of pyrrhotite throughout the mantle supports Goldschmidt's idea about a sulphide zone between the mantle and the core. Such a zone could serve as a primary source of ores. Volatile H 2 O and H 2 S are stable throughout the mantle. Some hydrocarbons decompose into a mixture of methane and carbon over a wide range of pressures and temperatures. Natural oil may be regarded as a mixture of metastable hydrocarbons. FeO does not dissociate into a mixture of Fe 2 O 3 and Fe at high pressure and temperature. Alkali‐free carbonate magmas may arise in the mantle. The greater the proportion of iron‐silicates in the mantle, the more probable is the existence of a ferrous‐ferric garnet zone at great depth.