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A calculated petrogenetic grid for the system K 2 O‐FeO‐MgO‐Al 2 O 3 ‐SiO 2 ‐H 2 O, with particular reference to contact‐metamorphosed pelites
Author(s) -
XU GUOWEI,
WILL T. M.,
POWELL R.
Publication year - 1994
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.1525-1314.1994.tb00006.x
Subject(s) - andalusite , kyanite , sillimanite , cordierite , muscovite , geology , quartz , biotite , mineral , corundum , staurolite , spinel , mineralogy , feldspar , chlorite , geochemistry , metamorphic rock , materials science , metallurgy , paleontology , ceramic
A petrogenetic grid is presented for the system KFMASH (K 2 O‐FeO‐MgO‐Al 2 O 3 ‐SiO 2 ‐H 2 O), including biotite, muscovite, K‐feldspar, chlorite, chloritoid, staurolite, cordierite, garnet, orthoamphibole, orthopyroxene, spinel, andalusite, sillimanite, kyanite, quartz and corundum with H 2 O in excess, which was calculated using the computer program THERMOCALC and the Powell and Holland internally consistent thermodynamic dataset. By removing the normal constraint of having quartz in excess, both quartz‐bearing and quartz‐absent equilibria are shown. Quartz‐absent equilibria are particularly relevant at high‐ T and low‐ P conditions, because of their common occurrence at these conditions. The calculated mineral assemblage and mineral compositional variations in terms of FeMg‐1 and (Fe, Mg)SiAl ‐2 exchange vectors are broadly compatible with observations on natural rocks, particularly when non‐KFMASH components are taken into account.