Title: Corundum-leucosome-bearing aluminous gneiss from Ayyarmalai, Southern Granulite Terrain, India: A textbook example of vapor phase-absent muscovite-melting in silica-undersaturated aluminous rocks
Abstract:An aluminous gneissic rock associated with high-pressure mafic and felsic granulites in the Palghat- Cauvery Shear Zone of southern India provides a classic example of quartz-absent muscovite melting....An aluminous gneissic rock associated with high-pressure mafic and felsic granulites in the Palghat- Cauvery Shear Zone of southern India provides a classic example of quartz-absent muscovite melting. The anatectic gneiss shows a conspicuous migmatitic structure defined by closely spaced centimeter to decimeter sized, corundum-bearing leucosomes developed in a weakly foliated mesosome of plagioclase (An21Ab77Or2) and biotite (4.9 wt% TiO2, XMg = 0.51-0.47). The boundaries between leucosome and mesosome domains are sharp, and no melanosome selvages are developed at the interface. Corundum occurs as euhedral crystals up to 2 cm in diameter, typically centered in the leucosome matrix of coarse-grained perthitic alkali feldspar (integrated composition: An2Ab35Or63), minor relict biotite (4.2-5.1 wt% TiO2, XMg = 0.48-0.46) and plagioclase (An21Ab78Or1). In some domains, the mesosomes also contain elongate clusters of similarly oriented smaller corundum plates that are intergrown with perthitic alkali feldspar, presumably replacing former kyanite blades.Read More
Publication Year: 2010
Publication Date: 2010-06-23
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 41
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Title: $Corundum-leucosome-bearing aluminous gneiss from Ayyarmalai, Southern Granulite Terrain, India: A textbook example of vapor phase-absent muscovite-melting in silica-undersaturated aluminous rocks
Abstract: An aluminous gneissic rock associated with high-pressure mafic and felsic granulites in the Palghat- Cauvery Shear Zone of southern India provides a classic example of quartz-absent muscovite melting. The anatectic gneiss shows a conspicuous migmatitic structure defined by closely spaced centimeter to decimeter sized, corundum-bearing leucosomes developed in a weakly foliated mesosome of plagioclase (An21Ab77Or2) and biotite (4.9 wt% TiO2, XMg = 0.51-0.47). The boundaries between leucosome and mesosome domains are sharp, and no melanosome selvages are developed at the interface. Corundum occurs as euhedral crystals up to 2 cm in diameter, typically centered in the leucosome matrix of coarse-grained perthitic alkali feldspar (integrated composition: An2Ab35Or63), minor relict biotite (4.2-5.1 wt% TiO2, XMg = 0.48-0.46) and plagioclase (An21Ab78Or1). In some domains, the mesosomes also contain elongate clusters of similarly oriented smaller corundum plates that are intergrown with perthitic alkali feldspar, presumably replacing former kyanite blades.