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Corona textures between kyanite, garnet and gedrite in gneisses from Errabiddy, Western Australia
Author(s) -
BAKER JUDY,
POWELL ROGER,
SANDIFORD MICHAEL,
MUHLING JAN
Publication year - 1987
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.1525-1314.1987.tb00390.x
Subject(s) - kyanite , geology , geochemistry , gneiss , sillimanite , cordierite , metamorphic rock , coesite , staurolite , petrology , quartz , tectonics , seismology , subduction , paleontology , eclogite , materials science , ceramic , biotite , composite material
Corona textures, which developed in alternating layers in rocks in a supracrustal belt at Errabiddy, Western Australia, involved: (a) The production of staurolite, cordierite and quartz or sapphirine between Kyanite and/or sillimanite and gedrite; and (b) The production of cordierite between garnet and gedrite. These textures are inconsistent with development along the same pressure–temperature path in the system FeO–MgO–Al 2 O 3 –SiO 2 –H 2 O, but can be accounted for if CaO, mainly in garnet, is taken into account. The sapphirine‐bearing kyanite–gedrite textures are explained by lower a (SiO 2 ) during their development. The assemblages indicate a consistent pressure–temperature ( P–T ) trajectory involving substantial uplift with only a slight decrease in temperature. The history of these rocks includes reheating of originally high‐grade rocks that had cooled to a stable conductive geotherm, followed by substantial, essentially isothermal uplift. The tectonic environment for this was presumably the one responsible for emplacement of the high‐grade terrain in the upper crust.