Department of Earth Sciences, Faculty of Science, Chiba University/Department of Crustal Studies, National Institute of Polar Research/Department of Earth Sciences, Faculty of Science, Chiba University/Department of Crustal Studies, National Institute of Polar Research/Department of Geology, Faculty of Science, Niigata University/Department of Earth System Science, Faculty of Science, Fukuoka University/Department of Crustal Studies, National Institute of Polar Research/Council for Geoscience/Department of Geology, Rand Afrikaans University
抄録(英)
Cordierite-phlogopite gneiss with spectacular coarse pseudomorphs of sillimanite after andalusite occurs as a kind of Mg-Al-rich rock in the Dabeeb-Hytkoras area of the granulite-faces western Namaqualand Metamorphic Complex. The sillimanite pseudomorphs are always fringed by spinel-cordierite coronas, which, in turn, are surrounded by cordierite mono-mineral zones. The spinel-cordierite coronas include minor amounts of sapphirine, corundum and rutile. The matrix comprises mainly cordierite and phlogopite with minor plagioclase and orthopyroxene plus a trace of quartz. Orthopyroxene is often replaced partially by symplectitic intergrowths of phlogopite and quartz. The modes of occurrence and chemical compositions of minerals indicate that the rock followed a prograde metamorphic P-T path from the andalusite to the sillimanite stability fields and a subsequent isobaric cooling path and that partial melting took place during granulite-facies metamorphism resulting in its present geochemical character.
雑誌書誌ID
AA00733561
雑誌名
Memoirs of National Institute of Polar Research. Special issue
New evidence for prograde metamorphism and partial melting of Mg-Al-rich granulites from western Namaqualand, South Africa
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KJ00000012967
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概要
