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Influence of ferric iron on the stability of mineral assemblages
Author(s) -
DIENER J. F. A.,
POWELL R.
Publication year - 2010
Publication title -
journal of metamorphic geology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.639
H-Index - 114
eISSN - 1525-1314
pISSN - 0263-4929
DOI - 10.1111/j.1525-1314.2010.00880.x
Subject(s) - pelite , ferric iron , mafic , metamorphic rock , mineral , geology , ferric , geochemistry , corundum , quartz , mineralogy , assemblage (archaeology) , chemistry , inorganic chemistry , ferrous , paleontology , organic chemistry
Ferric iron is present in all metamorphic rocks and has the ability to significantly affect their phase relations. However, the influence of ferric iron has commonly been ignored, or at least not been considered quantitatively, mainly because its abundance in rocks and minerals is not determined by routine analytical techniques. Mineral equilibria calculations that explicitly account for ferric iron can be used to examine its effect on the phase relations in rocks and, in principle, allow the estimation of the oxidation state of rocks. This is illustrated with calculated pseudosections in NCKFMASHTO for mafic and pelitic rock compositions. In addition, it is shown that ferric iron has the capacity to significantly increase the stability of the corundum + quartz assemblage, making it possible for this assemblage to exist at crustal P – T conditions in oxidized rocks of appropriate composition.