Title Sapphirine+quartz association in garnet; implication for ultrahigh-temperature metamorphism at Rundvagshetta, Lützow-Holm Complex, East Antarctica
Author Yoshimura, Y.; Motoyoshi, Y.; Miyamoto, T.
Author Affil Yoshimura, Y., Kochi University, Department of Natural Environmental Science, Kochi, Japan. Other: National Institute of Polar Research, Japan; Kyushu University, Japan; Chiba University, Japan; National Institute of Polar Research, Japan; Kyuschu University, Japan
Source Geodynamic evolution of East Antarctica; a key to the east-west Gondwana connection, edited by M. Satish-Kumar, Y. Motoyoshi, Y. Osanai, Y. Hiroi and K. Shiraishi. Geological Society Special Publications, Vol.308, p.377-390, . Publisher: Geological Society of London, London, United Kingdom. ISSN: 0305-8719. ISBN: 978-1-86239-268-7
Publication Date 2008
Notes In English. 46 refs. Ant. Acc. No: 85829
Index Terms Antarctica--East Antarctica; Antarctica--Queen Maud Land; aenigmatite group; Antarctica; biotite; Cambrian; chain silicates; cordierite; East Antarctica; electron probe data; feldspar group; framework silicates; garnet group; geochemistry; gneisses; granulites; high- grade metamorphism; International Polar Year 2007-08; IPY 2007-08 Research Publications; Lutzow-Holm Complex; major elements; metamorphic rocks; metamorphism; mica group; mineral assemblages; Neoproterozoic; nesosilicates; orthopyroxene; orthosilicates; P-T conditions; Paleozoic; plagioclase; Precambrian; Proterozoic; pyroxene group; quartz; Queen Maud Land; ring silicates; sapphirine; sheet silicates; silica minerals; silicates; temperature; ultrahigh temperature; upper Precambrian
Abstract We report the occurrence of sapphirine+quartz association within garnet porphyroblast in the garnet-orthopyroxene- sillimanite granulite (Grt-Opx-Sill granulite) from Rundvagshetta in the Lutzow- Holm Complex, East Antarctica. The granulites in the study area show a characteristic mineral assemblage consisting of orthopyroxene+sillimanite+quartz. The presence of sapphirine and quartz inclusions within garnet in the sapphirine-bearing Grt- Opx-Sill granulite suggests that metamorphic conditions changed from the stability field of orthopyroxene + sillimanite + quartz to that of sapphirine + quartz during the garnet growth. Peak metamorphic temperature conditions of about 1000-1100°C are obtained by ternary feldspar thermometry for these granulites. Similar temperatures were also estimated from the Al-in-orthopyroxene geothermometer. The granulites are also characterized by coarse-grained garnet, being partly surrounded by a fine-grained symplectite composed of orthopyroxene and cordierite, whereas sapphirine+cordierite symplectitic intergrowth occurs in the matrix. These textures imply that the area underwent isothermal decompression subsequent to ultrahigh-temperature metamorphism. The sapphirine-bearing Grt-Opx-Sill granulite is likely to be the restitic product of partial melting and shows signs of segregation and movement of melt.
URL http://hdl.handle.net/10.1144/SP308.18
Publication Type journal article
Record ID 290778