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CO 2 fugacity at high temperatures and pressures from experimental decarbonation reactions
Author(s) -
Haselton H. T.,
Sharp W. E.,
Newton R. C.
Publication year - 1978
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl005i009p00753
Subject(s) - fugacity , mantle (geology) , geology , mineral redox buffer , mineralogy , thermodynamics , geochemistry , physics
The presence of CO 2 in the upper mantle has been inferred from several sources of evidence. To aid the understanding of the behavior of CO 2 at high pressures and temperatures, CO 2 fugacities have been deduced from the following decarbonation reactions: MgCO 3 + SiO 2 = MgSiO 3 + CO 2 , MgCO 3 + MgSiO 3 = Mg 2 SiO 4 + CO 2 , MgCO 3 + TiO 2 = MgTiO 3 + CO 2 , and CaCO 3 + SiO 2 = CaSiO 3 + CO 2 . The deduced fugacities indicate that CO 2 is more compressible at high pressures than previously predicted. This discrepancy could cause serious errors in the calculation of stabilities of mineral assemblages under upper mantle conditions.