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Measured oxygen fugacities of the Angra dos Reis achondrite as a function of temperature

1977; Elsevier BV; Volume: 35; Issue: 2 Linguagem: Inglês

10.1016/0012-821x(77)90139-x

1385-013X

Robin Brett, J. S. Huebner, Motoaki Sato,

Geological and Geochemical Analysis

Measurements of the oxygen fugacity (ƒO2) as a function of temperature (T) were made on an interior bulk sample of the cumulate achondrite, Angra dos Reis. Data clustered between theƒO2-T relationship of the iron-wüstite assemblage and 1.2 log atm units above iron-wüstite. Interpretation of the data indicates that, throughout most of the cooling history of the meteorite, ƒO2 values were defined by equilibria involving iron-bearing species at values close to the ƒO2 of the assemblage iron-wüstite. Measured ƒO2 data are compatible with crystallization and cooling at pressures greater than 50 bars.