Ultrahigh-Temperature Mafic Granulites in the Rauer Group, East Antarctica: Evidence from Conventional Thermobarometry, Phase Equilibria Modeling, and Rare Earth Element Thermometry
Abstract The Rauer Group in East Antarctica is a typical high- to ultrahigh-temperature (HT–UHT) granulite-facies terrane. As UHT metamorphism has been recognized only in Mg–Al-rich pelitic granulites from the Mather Paragneiss, the regional extent of UHT metamorphism remains uncertain, which has hi...
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Oxford University Press (OUP)
2023
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Online Access: | http://dx.doi.org/10.1093/petrology/egad014 https://academic.oup.com/petrology/advance-article-pdf/doi/10.1093/petrology/egad014/49447774/egad014.pdf https://academic.oup.com/petrology/article-pdf/64/4/egad014/50266096/egad014.pdf |
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croxfordunivpr:10.1093/petrology/egad014 2024-09-09T19:12:04+00:00 Ultrahigh-Temperature Mafic Granulites in the Rauer Group, East Antarctica: Evidence from Conventional Thermobarometry, Phase Equilibria Modeling, and Rare Earth Element Thermometry Chen, Longyao Liu, Xiaochun Wang, Wei-(RZ) Liu, Jian 2023 http://dx.doi.org/10.1093/petrology/egad014 https://academic.oup.com/petrology/advance-article-pdf/doi/10.1093/petrology/egad014/49447774/egad014.pdf https://academic.oup.com/petrology/article-pdf/64/4/egad014/50266096/egad014.pdf en eng Oxford University Press (OUP) https://creativecommons.org/licenses/by/4.0/ Journal of Petrology volume 64, issue 4 ISSN 0022-3530 1460-2415 journal-article 2023 croxfordunivpr https://doi.org/10.1093/petrology/egad014 2024-08-27T04:14:22Z Abstract The Rauer Group in East Antarctica is a typical high- to ultrahigh-temperature (HT–UHT) granulite-facies terrane. As UHT metamorphism has been recognized only in Mg–Al-rich pelitic granulites from the Mather Paragneiss, the regional extent of UHT metamorphism remains uncertain, which has hindered our understanding of the genesis and tectonic setting of UHT metamorphism in the Rauer Group. In this study, representative samples of mafic granulite were selected from Archean crustal domains to constrain the peak metamorphic conditions and P–T path and to assess the regional extent of UHT metamorphism in the Rauer Group. Integrated results from mineral reaction histories, thermobarometry, and phase equilibria modeling indicate a multi-stage clockwise P–T evolution for mafic granulites involving pre-peak compression, heating to UHT peak conditions, post-peak near-isothermal decompression under UHT conditions, and subsequent decompressional cooling. The pre-peak prograde history is based mainly on the inclusion assemblage of clinopyroxene + plagioclase + amphibole + quartz + ilmenite ± orthopyroxene ± k-feldspar within porphyroblastic garnet and clinopyroxene and records the transformation from a quartz-present to quartz-absent system. The UHT peak conditions are well constrained at 930°C–1030°C and 10.6–12.8 kbar on the basis of the stability field of the observed peak assemblage of (orthopyroxene–quartz)-free garnet + clinopyroxene + plagioclase + amphibole + ilmenite + melt, as well as measured mineral compositions, including the high Ti content in amphibole (Ti = 0.38–0.42 p.f.u.), the anorthite content of coarse-grained plagioclase cores (XAn = 0.35–0.42), and the grossular content in garnet (XGrs = ~0.21) in P–T pseudosections. The peak T conditions are consistent with thermometric estimates in the range of 930°C–1030°C obtained from garnet–clinopyroxene, garnet–orthopyroxene, and Ti-in-amphibole thermometers, and are slightly lower than estimates (1020°C–1120°C) obtained from thermometers based on rare ... Article in Journal/Newspaper Antarc* Antarctica East Antarctica Oxford University Press East Antarctica Rauer Group ENVELOPE(77.833,77.833,-68.850,-68.850) Journal of Petrology |
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Open Polar |
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Oxford University Press |
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croxfordunivpr |
language |
English |
description |
Abstract The Rauer Group in East Antarctica is a typical high- to ultrahigh-temperature (HT–UHT) granulite-facies terrane. As UHT metamorphism has been recognized only in Mg–Al-rich pelitic granulites from the Mather Paragneiss, the regional extent of UHT metamorphism remains uncertain, which has hindered our understanding of the genesis and tectonic setting of UHT metamorphism in the Rauer Group. In this study, representative samples of mafic granulite were selected from Archean crustal domains to constrain the peak metamorphic conditions and P–T path and to assess the regional extent of UHT metamorphism in the Rauer Group. Integrated results from mineral reaction histories, thermobarometry, and phase equilibria modeling indicate a multi-stage clockwise P–T evolution for mafic granulites involving pre-peak compression, heating to UHT peak conditions, post-peak near-isothermal decompression under UHT conditions, and subsequent decompressional cooling. The pre-peak prograde history is based mainly on the inclusion assemblage of clinopyroxene + plagioclase + amphibole + quartz + ilmenite ± orthopyroxene ± k-feldspar within porphyroblastic garnet and clinopyroxene and records the transformation from a quartz-present to quartz-absent system. The UHT peak conditions are well constrained at 930°C–1030°C and 10.6–12.8 kbar on the basis of the stability field of the observed peak assemblage of (orthopyroxene–quartz)-free garnet + clinopyroxene + plagioclase + amphibole + ilmenite + melt, as well as measured mineral compositions, including the high Ti content in amphibole (Ti = 0.38–0.42 p.f.u.), the anorthite content of coarse-grained plagioclase cores (XAn = 0.35–0.42), and the grossular content in garnet (XGrs = ~0.21) in P–T pseudosections. The peak T conditions are consistent with thermometric estimates in the range of 930°C–1030°C obtained from garnet–clinopyroxene, garnet–orthopyroxene, and Ti-in-amphibole thermometers, and are slightly lower than estimates (1020°C–1120°C) obtained from thermometers based on rare ... |
format |
Article in Journal/Newspaper |
author |
Chen, Longyao Liu, Xiaochun Wang, Wei-(RZ) Liu, Jian |
spellingShingle |
Chen, Longyao Liu, Xiaochun Wang, Wei-(RZ) Liu, Jian Ultrahigh-Temperature Mafic Granulites in the Rauer Group, East Antarctica: Evidence from Conventional Thermobarometry, Phase Equilibria Modeling, and Rare Earth Element Thermometry |
author_facet |
Chen, Longyao Liu, Xiaochun Wang, Wei-(RZ) Liu, Jian |
author_sort |
Chen, Longyao |
title |
Ultrahigh-Temperature Mafic Granulites in the Rauer Group, East Antarctica: Evidence from Conventional Thermobarometry, Phase Equilibria Modeling, and Rare Earth Element Thermometry |
title_short |
Ultrahigh-Temperature Mafic Granulites in the Rauer Group, East Antarctica: Evidence from Conventional Thermobarometry, Phase Equilibria Modeling, and Rare Earth Element Thermometry |
title_full |
Ultrahigh-Temperature Mafic Granulites in the Rauer Group, East Antarctica: Evidence from Conventional Thermobarometry, Phase Equilibria Modeling, and Rare Earth Element Thermometry |
title_fullStr |
Ultrahigh-Temperature Mafic Granulites in the Rauer Group, East Antarctica: Evidence from Conventional Thermobarometry, Phase Equilibria Modeling, and Rare Earth Element Thermometry |
title_full_unstemmed |
Ultrahigh-Temperature Mafic Granulites in the Rauer Group, East Antarctica: Evidence from Conventional Thermobarometry, Phase Equilibria Modeling, and Rare Earth Element Thermometry |
title_sort |
ultrahigh-temperature mafic granulites in the rauer group, east antarctica: evidence from conventional thermobarometry, phase equilibria modeling, and rare earth element thermometry |
publisher |
Oxford University Press (OUP) |
publishDate |
2023 |
url |
http://dx.doi.org/10.1093/petrology/egad014 https://academic.oup.com/petrology/advance-article-pdf/doi/10.1093/petrology/egad014/49447774/egad014.pdf https://academic.oup.com/petrology/article-pdf/64/4/egad014/50266096/egad014.pdf |
long_lat |
ENVELOPE(77.833,77.833,-68.850,-68.850) |
geographic |
East Antarctica Rauer Group |
geographic_facet |
East Antarctica Rauer Group |
genre |
Antarc* Antarctica East Antarctica |
genre_facet |
Antarc* Antarctica East Antarctica |
op_source |
Journal of Petrology volume 64, issue 4 ISSN 0022-3530 1460-2415 |
op_rights |
https://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.1093/petrology/egad014 |
container_title |
Journal of Petrology |
_version_ |
1809752506202324992 |