Poly-phase metamorphism of garnet-bearing mafic granulite from the Larsemann Hills, East Antarctica: P-T path, U-Pb ages and tectonic implications
© 2017 Elsevier B.V. A rare garnet-bearing mafic granulite boulder has recently been identified from the Larsemann Hills, East Antarctica, with the development of two-stage decompression textures. Detailed petrographic study and P-T estimates suggest three distinct metamorphic stages: (1) peak ultra...
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Online Access: | https://hdl.handle.net/20.500.11937/66404 https://doi.org/10.1016/j.precamres.2017.12.045 |
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ftcurtin:oai:espace.curtin.edu.au:20.500.11937/66404 2023-06-11T04:05:07+02:00 Poly-phase metamorphism of garnet-bearing mafic granulite from the Larsemann Hills, East Antarctica: P-T path, U-Pb ages and tectonic implications Tong, L. Liu, Z. Li, Zheng-Xiang Liu, X. Zhou, X. 2018 restricted https://hdl.handle.net/20.500.11937/66404 https://doi.org/10.1016/j.precamres.2017.12.045 unknown Elsevier BV http://hdl.handle.net/20.500.11937/66404 doi:10.1016/j.precamres.2017.12.045 Journal Article 2018 ftcurtin https://doi.org/20.500.11937/6640410.1016/j.precamres.2017.12.045 2023-05-30T19:52:04Z © 2017 Elsevier B.V. A rare garnet-bearing mafic granulite boulder has recently been identified from the Larsemann Hills, East Antarctica, with the development of two-stage decompression textures. Detailed petrographic study and P-T estimates suggest three distinct metamorphic stages: (1) peak ultrahigh-temperature (UHT) stage (M1) represented by coarse-grained garnet-orthopyroxene-bearing porphyroblastic assemblage, with P-T conditions of 9.3 kbar and 900-950 °C; (2) post-peak decompression stage I (M2) represented by relatively coarse-grained orthopyroxene-plagioclase-ilmenite-bearing corona assemblage, with P-T conditions of 7.2-7.6 kbar and 810-830 °C; and (3) post-peak decompression stage II (M3) represented by fine-grained orthopyroxene-plagioclase-ilmenite-bearing symplectite assemblage on garnets and along garnet cracks, with P-T conditions of 6.2-6.9 kbar and 730-770 °C. Combined with P-T pseudosection calculation in the NCKFMASHTO system, these P-T data define a clockwise P-T path with post-peak two-stage decompression accompanied by important cooling. LA-ICP-MS zircon U-Pb age dating results show two weighted mean ages of 927 ± 13 Ma and 547 ± 30 Ma, suggesting that M1 UHT stage occurred in the early Neoproterozoic Rayner orogeny (990-900 Ma), whereas M2-M3 stages occurred during the early Palaeozoic Pan-African tectonic event (550-500 Ma). The peak P-T conditions, post-peak two-stage decompression P-T path and age data resemble those of the early Neoproterozoic garnet-bearing mafic granulite on Søstrene Island. It is inferred that the mafic granulite boulder may have been derived from the bedrock under inland ice sheet of the Larsemann Hills. Thus, the early Neoproterozoic metamorphism (M1) may reflect crustal thickening followed by post-orogenic extension likely associated with the assembly of Rodinia continent, while the overprinting of early Palaeozoic metamorphism (M2-M3) may reflect an extensive intra-continental reworking. Article in Journal/Newspaper Antarc* Antarctica East Antarctica Ice Sheet Curtin University: espace East Antarctica Larsemann Hills ENVELOPE(76.217,76.217,-69.400,-69.400) Rayner ENVELOPE(-45.166,-45.166,-60.650,-60.650) Søstrene ENVELOPE(75.503,75.503,-69.588,-69.588) Precambrian Research 326 385 398 |
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Open Polar |
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Curtin University: espace |
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description |
© 2017 Elsevier B.V. A rare garnet-bearing mafic granulite boulder has recently been identified from the Larsemann Hills, East Antarctica, with the development of two-stage decompression textures. Detailed petrographic study and P-T estimates suggest three distinct metamorphic stages: (1) peak ultrahigh-temperature (UHT) stage (M1) represented by coarse-grained garnet-orthopyroxene-bearing porphyroblastic assemblage, with P-T conditions of 9.3 kbar and 900-950 °C; (2) post-peak decompression stage I (M2) represented by relatively coarse-grained orthopyroxene-plagioclase-ilmenite-bearing corona assemblage, with P-T conditions of 7.2-7.6 kbar and 810-830 °C; and (3) post-peak decompression stage II (M3) represented by fine-grained orthopyroxene-plagioclase-ilmenite-bearing symplectite assemblage on garnets and along garnet cracks, with P-T conditions of 6.2-6.9 kbar and 730-770 °C. Combined with P-T pseudosection calculation in the NCKFMASHTO system, these P-T data define a clockwise P-T path with post-peak two-stage decompression accompanied by important cooling. LA-ICP-MS zircon U-Pb age dating results show two weighted mean ages of 927 ± 13 Ma and 547 ± 30 Ma, suggesting that M1 UHT stage occurred in the early Neoproterozoic Rayner orogeny (990-900 Ma), whereas M2-M3 stages occurred during the early Palaeozoic Pan-African tectonic event (550-500 Ma). The peak P-T conditions, post-peak two-stage decompression P-T path and age data resemble those of the early Neoproterozoic garnet-bearing mafic granulite on Søstrene Island. It is inferred that the mafic granulite boulder may have been derived from the bedrock under inland ice sheet of the Larsemann Hills. Thus, the early Neoproterozoic metamorphism (M1) may reflect crustal thickening followed by post-orogenic extension likely associated with the assembly of Rodinia continent, while the overprinting of early Palaeozoic metamorphism (M2-M3) may reflect an extensive intra-continental reworking. |
format |
Article in Journal/Newspaper |
author |
Tong, L. Liu, Z. Li, Zheng-Xiang Liu, X. Zhou, X. |
spellingShingle |
Tong, L. Liu, Z. Li, Zheng-Xiang Liu, X. Zhou, X. Poly-phase metamorphism of garnet-bearing mafic granulite from the Larsemann Hills, East Antarctica: P-T path, U-Pb ages and tectonic implications |
author_facet |
Tong, L. Liu, Z. Li, Zheng-Xiang Liu, X. Zhou, X. |
author_sort |
Tong, L. |
title |
Poly-phase metamorphism of garnet-bearing mafic granulite from the Larsemann Hills, East Antarctica: P-T path, U-Pb ages and tectonic implications |
title_short |
Poly-phase metamorphism of garnet-bearing mafic granulite from the Larsemann Hills, East Antarctica: P-T path, U-Pb ages and tectonic implications |
title_full |
Poly-phase metamorphism of garnet-bearing mafic granulite from the Larsemann Hills, East Antarctica: P-T path, U-Pb ages and tectonic implications |
title_fullStr |
Poly-phase metamorphism of garnet-bearing mafic granulite from the Larsemann Hills, East Antarctica: P-T path, U-Pb ages and tectonic implications |
title_full_unstemmed |
Poly-phase metamorphism of garnet-bearing mafic granulite from the Larsemann Hills, East Antarctica: P-T path, U-Pb ages and tectonic implications |
title_sort |
poly-phase metamorphism of garnet-bearing mafic granulite from the larsemann hills, east antarctica: p-t path, u-pb ages and tectonic implications |
publisher |
Elsevier BV |
publishDate |
2018 |
url |
https://hdl.handle.net/20.500.11937/66404 https://doi.org/10.1016/j.precamres.2017.12.045 |
long_lat |
ENVELOPE(76.217,76.217,-69.400,-69.400) ENVELOPE(-45.166,-45.166,-60.650,-60.650) ENVELOPE(75.503,75.503,-69.588,-69.588) |
geographic |
East Antarctica Larsemann Hills Rayner Søstrene |
geographic_facet |
East Antarctica Larsemann Hills Rayner Søstrene |
genre |
Antarc* Antarctica East Antarctica Ice Sheet |
genre_facet |
Antarc* Antarctica East Antarctica Ice Sheet |
op_relation |
http://hdl.handle.net/20.500.11937/66404 doi:10.1016/j.precamres.2017.12.045 |
op_doi |
https://doi.org/20.500.11937/6640410.1016/j.precamres.2017.12.045 |
container_title |
Precambrian Research |
container_volume |
326 |
container_start_page |
385 |
op_container_end_page |
398 |
_version_ |
1768371999075205120 |