TY - JOUR
T1 - Metamorphic P-T conditions and variation of REE between two garnet generations from granulites in the Sør-Rondane mountains, East Antarctica
AU - Baba, Sotaro
AU - Osanai, Yasuhito
AU - Adachi, Tatsuro
AU - Nakano, Nobuhiko
AU - Hokada, Tomokazu
AU - Toyoshima, Tsuyoshi
N1 - Funding Information:
This work was partly supported by the National Institute of Polar Research [General Collaboration Projects 25–17] and the Japan Society for the Promotion of Science (JSPS) [15 K05346 to S. B.]. We would like to thank the members of 48th and 49th Japan Antarctic Research Expedition (JARE), and the crew of the icebreaker SHIRASE. We also thank A. Hubert, G. Johnson-Amin, and members of the Belgian Antarctic Research Station (2007–2008) for supporting our fieldwork. We acknowledge K. Shiraishi, Y. Motoyoshi, Y. Hiroi, H. Ishizuka, T. Kawasaki, M. Owada. K. Das and E.S. Grew for valuable discussions and comments. Constructive comments by Shah Wali Faryad, Leo Kriegsman, Fawna Korhonen, Gary Stevens, Geoffrey Grantham and an anonymous reviewer improved this manuscript and are gratefully acknowledged. We thank Shah Wali Faryad and M.A.T.M. Broekmans for editorial handling.
Publisher Copyright:
© 2019, Springer-Verlag GmbH Austria, part of Springer Nature.
PY - 2019/12/1
Y1 - 2019/12/1
N2 - In this paper, we describe the metamorphic conditions of Fe-rich granulite and variations in rare earth elements (REE) between peak garnet porphyroblasts and secondary garnet coronae. The Fe-rich granulites were collected from Vesthaugen, Sør-Rondane Mountains, East Antarctica, and consist mainly of cordierite, garnet, spinel, perthite, K-feldspar, plagioclase, and orthopyroxene or sillimanite. Temperatures estimated from perthitc–mesoperthitic feldspar compositions, experimentally calibrated geothermobarometers and the modeling of P-T pseudosections suggest that the rocks experienced peak ultrahigh-temperature (UHT) metamorphic conditions of 900–950 °C and 5.0 ± 0.5 kbar. Spinel contains quartz inclusions that also provide evidence for UHT metamorphism. Evidence of partial melting is characterized by the presence of leucocratic bands. The second generation of garnet occurs as coronae around spinel, formed during isobaric cooling following the peak conditions of UHT metamorphism. Garnet coronae and garnet porphyroblasts have distinct trace element patterns. Textural evidence and REE geochemistry suggest that the development of garnet coronae was controlled by (1) the REE composition of reactant phases and melt and/or (2) the crystallization of HREE-rich accessory phases (e.g., zircon and monazite) during secondary garnet growth.
AB - In this paper, we describe the metamorphic conditions of Fe-rich granulite and variations in rare earth elements (REE) between peak garnet porphyroblasts and secondary garnet coronae. The Fe-rich granulites were collected from Vesthaugen, Sør-Rondane Mountains, East Antarctica, and consist mainly of cordierite, garnet, spinel, perthite, K-feldspar, plagioclase, and orthopyroxene or sillimanite. Temperatures estimated from perthitc–mesoperthitic feldspar compositions, experimentally calibrated geothermobarometers and the modeling of P-T pseudosections suggest that the rocks experienced peak ultrahigh-temperature (UHT) metamorphic conditions of 900–950 °C and 5.0 ± 0.5 kbar. Spinel contains quartz inclusions that also provide evidence for UHT metamorphism. Evidence of partial melting is characterized by the presence of leucocratic bands. The second generation of garnet occurs as coronae around spinel, formed during isobaric cooling following the peak conditions of UHT metamorphism. Garnet coronae and garnet porphyroblasts have distinct trace element patterns. Textural evidence and REE geochemistry suggest that the development of garnet coronae was controlled by (1) the REE composition of reactant phases and melt and/or (2) the crystallization of HREE-rich accessory phases (e.g., zircon and monazite) during secondary garnet growth.
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U2 - 10.1007/s00710-019-00680-0
DO - 10.1007/s00710-019-00680-0
M3 - Article
AN - SCOPUS:85069933612
SN - 0930-0708
VL - 113
SP - 821
EP - 845
JO - Mineralogy and Petrology
JF - Mineralogy and Petrology
IS - 6
ER -