Early Neoproterozoic granulite facies metamorphism of mafic dykes from the Vestfold Block, east Antarctica
Abstract Proterozoic mafic dykes from the southwestern Vestfold Block experienced heterogeneous granulite facies metamorphism, characterized by spotted or fractured garnet‐bearing aggregates in garnet‐absent groundmass. The garnet‐absent groundmass typically preserves an ophitic texture composed of...
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crwiley:10.1111/jmg.12106 2024-06-23T07:46:32+00:00 Early Neoproterozoic granulite facies metamorphism of mafic dykes from the Vestfold Block, east Antarctica Liu, X. C. Wang, W.‐(R. Z.) Zhao, Y. Liu, J. Song, B. National Natural Science Foundation of China Geological Investigation Project of China Geological Survey Chinese Polar Environment Comprehensive investigation & Assessment Programmes 2014 http://dx.doi.org/10.1111/jmg.12106 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fjmg.12106 https://onlinelibrary.wiley.com/doi/pdf/10.1111/jmg.12106 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Journal of Metamorphic Geology volume 32, issue 9, page 1041-1062 ISSN 0263-4929 1525-1314 journal-article 2014 crwiley https://doi.org/10.1111/jmg.12106 2024-06-11T04:43:23Z Abstract Proterozoic mafic dykes from the southwestern Vestfold Block experienced heterogeneous granulite facies metamorphism, characterized by spotted or fractured garnet‐bearing aggregates in garnet‐absent groundmass. The garnet‐absent groundmass typically preserves an ophitic texture composed of lathy plagioclase, intergranular clinopyroxene and Fe–Ti oxides. Garnet‐bearing domains consist mainly of a metamorphic assemblage of garnet, clinopyroxene, orthopyroxene, hornblende, biotite, plagioclase, K‐feldspar, quartz and Fe–Ti oxides. Chemical compositions and textural relationships suggest that these metamorphic minerals reached local equilibrium in the centre of the garnet‐bearing domains. Pseudosection calculations in the model system NCFMASHTO (Na 2 O–CaO–FeO–MgO–Al 2 O 3 –SiO 2 –H 2 O–TiO 2 –Fe 2 O 3 ) yield P – T estimates of 820–870 °C and 8.4–9.7 kbar. Ion microprobe U–Pb zircon dating reveals that the NW ‐ and N‐trending mafic dykes were emplaced at 1764 ± 25 and 1232 ± 12 Ma, respectively, whereas their metamorphic ages cluster between 957 ± 7 and 938 ± 9 Ma. The identification of granulite facies mineral inclusions in metamorphic zircon domains is also consistent with early Neoproterozoic metamorphism. Therefore, the southwestern margin of the Vestfold Block is inferred to have been buried to depths of ~30–35 km beneath the Rayner orogen during the late stage of the late Mesoproterozoic/early Neoproterozoic collision between the Indian craton and east Antarctica (i.e. the Lambert Terrane or the Ruker craton including the Lambert Terrane). The lack of penetrative deformation and intensive fluid–rock interaction in the rigid Vestfold Block prevented the nucleation and growth of garnet and resulted in the heterogeneous granulite facies metamorphism of the mafic dykes. Article in Journal/Newspaper Antarc* Antarctica East Antarctica Wiley Online Library East Antarctica Indian Rayner ENVELOPE(-45.166,-45.166,-60.650,-60.650) Ruker ENVELOPE(64.583,64.583,-73.583,-73.583) Vestfold Journal of Metamorphic Geology 32 9 1041 1062 |
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Wiley Online Library |
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English |
description |
Abstract Proterozoic mafic dykes from the southwestern Vestfold Block experienced heterogeneous granulite facies metamorphism, characterized by spotted or fractured garnet‐bearing aggregates in garnet‐absent groundmass. The garnet‐absent groundmass typically preserves an ophitic texture composed of lathy plagioclase, intergranular clinopyroxene and Fe–Ti oxides. Garnet‐bearing domains consist mainly of a metamorphic assemblage of garnet, clinopyroxene, orthopyroxene, hornblende, biotite, plagioclase, K‐feldspar, quartz and Fe–Ti oxides. Chemical compositions and textural relationships suggest that these metamorphic minerals reached local equilibrium in the centre of the garnet‐bearing domains. Pseudosection calculations in the model system NCFMASHTO (Na 2 O–CaO–FeO–MgO–Al 2 O 3 –SiO 2 –H 2 O–TiO 2 –Fe 2 O 3 ) yield P – T estimates of 820–870 °C and 8.4–9.7 kbar. Ion microprobe U–Pb zircon dating reveals that the NW ‐ and N‐trending mafic dykes were emplaced at 1764 ± 25 and 1232 ± 12 Ma, respectively, whereas their metamorphic ages cluster between 957 ± 7 and 938 ± 9 Ma. The identification of granulite facies mineral inclusions in metamorphic zircon domains is also consistent with early Neoproterozoic metamorphism. Therefore, the southwestern margin of the Vestfold Block is inferred to have been buried to depths of ~30–35 km beneath the Rayner orogen during the late stage of the late Mesoproterozoic/early Neoproterozoic collision between the Indian craton and east Antarctica (i.e. the Lambert Terrane or the Ruker craton including the Lambert Terrane). The lack of penetrative deformation and intensive fluid–rock interaction in the rigid Vestfold Block prevented the nucleation and growth of garnet and resulted in the heterogeneous granulite facies metamorphism of the mafic dykes. |
author2 |
National Natural Science Foundation of China Geological Investigation Project of China Geological Survey Chinese Polar Environment Comprehensive investigation & Assessment Programmes |
format |
Article in Journal/Newspaper |
author |
Liu, X. C. Wang, W.‐(R. Z.) Zhao, Y. Liu, J. Song, B. |
spellingShingle |
Liu, X. C. Wang, W.‐(R. Z.) Zhao, Y. Liu, J. Song, B. Early Neoproterozoic granulite facies metamorphism of mafic dykes from the Vestfold Block, east Antarctica |
author_facet |
Liu, X. C. Wang, W.‐(R. Z.) Zhao, Y. Liu, J. Song, B. |
author_sort |
Liu, X. C. |
title |
Early Neoproterozoic granulite facies metamorphism of mafic dykes from the Vestfold Block, east Antarctica |
title_short |
Early Neoproterozoic granulite facies metamorphism of mafic dykes from the Vestfold Block, east Antarctica |
title_full |
Early Neoproterozoic granulite facies metamorphism of mafic dykes from the Vestfold Block, east Antarctica |
title_fullStr |
Early Neoproterozoic granulite facies metamorphism of mafic dykes from the Vestfold Block, east Antarctica |
title_full_unstemmed |
Early Neoproterozoic granulite facies metamorphism of mafic dykes from the Vestfold Block, east Antarctica |
title_sort |
early neoproterozoic granulite facies metamorphism of mafic dykes from the vestfold block, east antarctica |
publisher |
Wiley |
publishDate |
2014 |
url |
http://dx.doi.org/10.1111/jmg.12106 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fjmg.12106 https://onlinelibrary.wiley.com/doi/pdf/10.1111/jmg.12106 |
long_lat |
ENVELOPE(-45.166,-45.166,-60.650,-60.650) ENVELOPE(64.583,64.583,-73.583,-73.583) |
geographic |
East Antarctica Indian Rayner Ruker Vestfold |
geographic_facet |
East Antarctica Indian Rayner Ruker Vestfold |
genre |
Antarc* Antarctica East Antarctica |
genre_facet |
Antarc* Antarctica East Antarctica |
op_source |
Journal of Metamorphic Geology volume 32, issue 9, page 1041-1062 ISSN 0263-4929 1525-1314 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1111/jmg.12106 |
container_title |
Journal of Metamorphic Geology |
container_volume |
32 |
container_issue |
9 |
container_start_page |
1041 |
op_container_end_page |
1062 |
_version_ |
1802646544560685056 |