Fluid-induced high-temperature metasomatism at Rundvågshetta in the Lützow-Holm Complex, East Antarctica: Implications for the role of brine during granulite formation
We report new petrological, phase equilibria modeling, and fluid inclusion data for pelitic and mafic granulites from Rundvågshetta in the highest-grade region of the Neoproterozoic Lützow-Holm Complex (LHC), East Antarctica, and provide unequivocal evidence for fluid-rock interaction and high-tempe...
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ftdoajarticles:oai:doaj.org/article:e9068af0610940ab9c7f9367100121c3 2023-10-01T03:51:37+02:00 Fluid-induced high-temperature metasomatism at Rundvågshetta in the Lützow-Holm Complex, East Antarctica: Implications for the role of brine during granulite formation Kazuki Takahashi Toshiaki Tsunogae Emmanuel Nwachukwu Ugwuonah 2018-09-01T00:00:00Z https://doi.org/10.1016/j.gsf.2017.11.010 https://doaj.org/article/e9068af0610940ab9c7f9367100121c3 EN eng Elsevier http://www.sciencedirect.com/science/article/pii/S1674987117302050 https://doaj.org/toc/1674-9871 1674-9871 doi:10.1016/j.gsf.2017.11.010 https://doaj.org/article/e9068af0610940ab9c7f9367100121c3 Geoscience Frontiers, Vol 9, Iss 5, Pp 1309-1323 (2018) Geology QE1-996.5 article 2018 ftdoajarticles https://doi.org/10.1016/j.gsf.2017.11.010 2023-09-03T00:36:05Z We report new petrological, phase equilibria modeling, and fluid inclusion data for pelitic and mafic granulites from Rundvågshetta in the highest-grade region of the Neoproterozoic Lützow-Holm Complex (LHC), East Antarctica, and provide unequivocal evidence for fluid-rock interaction and high-temperature metasomatism in the presence of brine fluid. The studied locality is composed dominantly of well-foliated pelitic granulite (K-feldspar + quartz + sillimanite + garnet + ilmenite) with foliation-parallel bands and/or layers of mafic granulite (plagioclase + orthopyroxene + garnet + ilmenite + quartz + biotite). The boundary between the two lithologies is defined by thin (about 1–20 cm in thick) garnet-rich layers with a common mineral assemblage of garnet + plagioclase + quartz + ilmenite + biotite ± orthopyroxene. Systematic increase of grossular and decrease of pyrope contents in garnet as well as decreasing Mg/(Fe + Mg) ratio of biotite from the pelitic granulite to garnet-rich rock and mafic granulite suggest that the garnet-rich layer was formed by metasomatic interaction between the two granulite lithologies. Phase equilibria modeling in the system NCKFMASHTO demonstrates that the metasomatism took place at 850–860 °C, which is slightly lower than the peak metamorphism of this region, and the modal abundance of garnet is the highest along the metapelite–metabasite boundary (up to 40%), which is consistent with the field and thin section observations. The occurrence of brine (7.0–10.9 wt.% NaCleq for ice melting or 25.1–25.5 wt.% NaCleq for hydrohalite melting) fluid inclusions as a primary phase trapped within plagioclase in the garnet-rich layer and the occurrence of Cl-rich biotite (Cl = 0.22–0.60 wt.%) in the metasomatic rock compared to that in pelitic (0.15–0.24 wt.%) and mafic (0.06–0.13 wt.%) granulites suggest infiltration of brine fluid could have given rise to the high-temperature metasomatism. The fluid might have been derived from external sources possibly related to the formation of major ... Article in Journal/Newspaper Antarc* Antarctica East Antarctica Directory of Open Access Journals: DOAJ Articles East Antarctica Geoscience Frontiers 9 5 1309 1323 |
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Open Polar |
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Directory of Open Access Journals: DOAJ Articles |
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language |
English |
topic |
Geology QE1-996.5 |
spellingShingle |
Geology QE1-996.5 Kazuki Takahashi Toshiaki Tsunogae Emmanuel Nwachukwu Ugwuonah Fluid-induced high-temperature metasomatism at Rundvågshetta in the Lützow-Holm Complex, East Antarctica: Implications for the role of brine during granulite formation |
topic_facet |
Geology QE1-996.5 |
description |
We report new petrological, phase equilibria modeling, and fluid inclusion data for pelitic and mafic granulites from Rundvågshetta in the highest-grade region of the Neoproterozoic Lützow-Holm Complex (LHC), East Antarctica, and provide unequivocal evidence for fluid-rock interaction and high-temperature metasomatism in the presence of brine fluid. The studied locality is composed dominantly of well-foliated pelitic granulite (K-feldspar + quartz + sillimanite + garnet + ilmenite) with foliation-parallel bands and/or layers of mafic granulite (plagioclase + orthopyroxene + garnet + ilmenite + quartz + biotite). The boundary between the two lithologies is defined by thin (about 1–20 cm in thick) garnet-rich layers with a common mineral assemblage of garnet + plagioclase + quartz + ilmenite + biotite ± orthopyroxene. Systematic increase of grossular and decrease of pyrope contents in garnet as well as decreasing Mg/(Fe + Mg) ratio of biotite from the pelitic granulite to garnet-rich rock and mafic granulite suggest that the garnet-rich layer was formed by metasomatic interaction between the two granulite lithologies. Phase equilibria modeling in the system NCKFMASHTO demonstrates that the metasomatism took place at 850–860 °C, which is slightly lower than the peak metamorphism of this region, and the modal abundance of garnet is the highest along the metapelite–metabasite boundary (up to 40%), which is consistent with the field and thin section observations. The occurrence of brine (7.0–10.9 wt.% NaCleq for ice melting or 25.1–25.5 wt.% NaCleq for hydrohalite melting) fluid inclusions as a primary phase trapped within plagioclase in the garnet-rich layer and the occurrence of Cl-rich biotite (Cl = 0.22–0.60 wt.%) in the metasomatic rock compared to that in pelitic (0.15–0.24 wt.%) and mafic (0.06–0.13 wt.%) granulites suggest infiltration of brine fluid could have given rise to the high-temperature metasomatism. The fluid might have been derived from external sources possibly related to the formation of major ... |
format |
Article in Journal/Newspaper |
author |
Kazuki Takahashi Toshiaki Tsunogae Emmanuel Nwachukwu Ugwuonah |
author_facet |
Kazuki Takahashi Toshiaki Tsunogae Emmanuel Nwachukwu Ugwuonah |
author_sort |
Kazuki Takahashi |
title |
Fluid-induced high-temperature metasomatism at Rundvågshetta in the Lützow-Holm Complex, East Antarctica: Implications for the role of brine during granulite formation |
title_short |
Fluid-induced high-temperature metasomatism at Rundvågshetta in the Lützow-Holm Complex, East Antarctica: Implications for the role of brine during granulite formation |
title_full |
Fluid-induced high-temperature metasomatism at Rundvågshetta in the Lützow-Holm Complex, East Antarctica: Implications for the role of brine during granulite formation |
title_fullStr |
Fluid-induced high-temperature metasomatism at Rundvågshetta in the Lützow-Holm Complex, East Antarctica: Implications for the role of brine during granulite formation |
title_full_unstemmed |
Fluid-induced high-temperature metasomatism at Rundvågshetta in the Lützow-Holm Complex, East Antarctica: Implications for the role of brine during granulite formation |
title_sort |
fluid-induced high-temperature metasomatism at rundvågshetta in the lützow-holm complex, east antarctica: implications for the role of brine during granulite formation |
publisher |
Elsevier |
publishDate |
2018 |
url |
https://doi.org/10.1016/j.gsf.2017.11.010 https://doaj.org/article/e9068af0610940ab9c7f9367100121c3 |
geographic |
East Antarctica |
geographic_facet |
East Antarctica |
genre |
Antarc* Antarctica East Antarctica |
genre_facet |
Antarc* Antarctica East Antarctica |
op_source |
Geoscience Frontiers, Vol 9, Iss 5, Pp 1309-1323 (2018) |
op_relation |
http://www.sciencedirect.com/science/article/pii/S1674987117302050 https://doaj.org/toc/1674-9871 1674-9871 doi:10.1016/j.gsf.2017.11.010 https://doaj.org/article/e9068af0610940ab9c7f9367100121c3 |
op_doi |
https://doi.org/10.1016/j.gsf.2017.11.010 |
container_title |
Geoscience Frontiers |
container_volume |
9 |
container_issue |
5 |
container_start_page |
1309 |
op_container_end_page |
1323 |
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1778516766491672576 |