Pan-African extension and near-isothermal exhumation of a granulite facies terrain, Dronning Maud Land, Antarctica
The Mühlig-Hofmann- and Filchnerfjella in central Dronning Maud Land, Antarctica, consist of series of granitoid igneous rocks emplaced in granulite and upper amphibolite facies metamorphic rocks. The area has experienced high-temperature metamorphism followed by near-isothermal decompression, parti...
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crcambridgeupr:10.1017/s0016756804009859 2024-09-15T17:46:07+00:00 Pan-African extension and near-isothermal exhumation of a granulite facies terrain, Dronning Maud Land, Antarctica ENGVIK, A. K. ELVEVOLD, S. 2004 http://dx.doi.org/10.1017/s0016756804009859 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0016756804009859 en eng Cambridge University Press (CUP) https://www.cambridge.org/core/terms Geological Magazine volume 141, issue 6, page 649-660 ISSN 0016-7568 1469-5081 journal-article 2004 crcambridgeupr https://doi.org/10.1017/s0016756804009859 2024-07-31T04:03:35Z The Mühlig-Hofmann- and Filchnerfjella in central Dronning Maud Land, Antarctica, consist of series of granitoid igneous rocks emplaced in granulite and upper amphibolite facies metamorphic rocks. The area has experienced high-temperature metamorphism followed by near-isothermal decompression, partial crustal melting, voluminous magmatism and extensional exhumation during the later phase of the late Neoproterozoic to Cambrian Pan-African event. Remnants of kyanite–garnet–ferritschermakite–rutile assemblages indicate an early higher-pressure metamorphism and crustal overthickening. The gneisses experienced peak granulite facies temperatures of 800–900 °C at intermediate pressures. Breakdown of garnet + sillimanite + spinel-bearing assemblages to cordierite shows subsequent re-equilibration to lower pressures. An E–W foliation dominating the gneisses illustrates transposition of migmatites and leucocratic melts which evolved during the near-isothermal decompression. Occurrence of extensional shear bands and shear zones evolving from the ductile partial melting stage through semiductile towards brittle conditions, shows that the uplift persisted towards brittle crustal conditions under tectonic W/SW-vergent extension. Late-orogenic Pan-African quartz syenites intruded after formation of the main gneiss fabric contain narrow semiductile to brittle shear zones, illustrating that the extensional exhumation continued also after their emplacement. The latest record of the Pan-African event is late-magmatic fluid infiltration around 350–400 °C and 2 kbar. At this stage the Pan-African crust had undergone 15–20 km exhumation from the peak granulite facies conditions. We conclude that the later phase of the Pan-African event in central Dronning Maud Land is characterized by a near-isothermal decompression P–T path and extensional structures indicating tectonic exhumation, which is most likely related to a late-orogenic collapsing phase of the Pan-African orogen. Article in Journal/Newspaper Antarc* Antarctica Dronning Maud Land Cambridge University Press Geological Magazine 141 6 649 660 |
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Cambridge University Press |
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crcambridgeupr |
language |
English |
description |
The Mühlig-Hofmann- and Filchnerfjella in central Dronning Maud Land, Antarctica, consist of series of granitoid igneous rocks emplaced in granulite and upper amphibolite facies metamorphic rocks. The area has experienced high-temperature metamorphism followed by near-isothermal decompression, partial crustal melting, voluminous magmatism and extensional exhumation during the later phase of the late Neoproterozoic to Cambrian Pan-African event. Remnants of kyanite–garnet–ferritschermakite–rutile assemblages indicate an early higher-pressure metamorphism and crustal overthickening. The gneisses experienced peak granulite facies temperatures of 800–900 °C at intermediate pressures. Breakdown of garnet + sillimanite + spinel-bearing assemblages to cordierite shows subsequent re-equilibration to lower pressures. An E–W foliation dominating the gneisses illustrates transposition of migmatites and leucocratic melts which evolved during the near-isothermal decompression. Occurrence of extensional shear bands and shear zones evolving from the ductile partial melting stage through semiductile towards brittle conditions, shows that the uplift persisted towards brittle crustal conditions under tectonic W/SW-vergent extension. Late-orogenic Pan-African quartz syenites intruded after formation of the main gneiss fabric contain narrow semiductile to brittle shear zones, illustrating that the extensional exhumation continued also after their emplacement. The latest record of the Pan-African event is late-magmatic fluid infiltration around 350–400 °C and 2 kbar. At this stage the Pan-African crust had undergone 15–20 km exhumation from the peak granulite facies conditions. We conclude that the later phase of the Pan-African event in central Dronning Maud Land is characterized by a near-isothermal decompression P–T path and extensional structures indicating tectonic exhumation, which is most likely related to a late-orogenic collapsing phase of the Pan-African orogen. |
format |
Article in Journal/Newspaper |
author |
ENGVIK, A. K. ELVEVOLD, S. |
spellingShingle |
ENGVIK, A. K. ELVEVOLD, S. Pan-African extension and near-isothermal exhumation of a granulite facies terrain, Dronning Maud Land, Antarctica |
author_facet |
ENGVIK, A. K. ELVEVOLD, S. |
author_sort |
ENGVIK, A. K. |
title |
Pan-African extension and near-isothermal exhumation of a granulite facies terrain, Dronning Maud Land, Antarctica |
title_short |
Pan-African extension and near-isothermal exhumation of a granulite facies terrain, Dronning Maud Land, Antarctica |
title_full |
Pan-African extension and near-isothermal exhumation of a granulite facies terrain, Dronning Maud Land, Antarctica |
title_fullStr |
Pan-African extension and near-isothermal exhumation of a granulite facies terrain, Dronning Maud Land, Antarctica |
title_full_unstemmed |
Pan-African extension and near-isothermal exhumation of a granulite facies terrain, Dronning Maud Land, Antarctica |
title_sort |
pan-african extension and near-isothermal exhumation of a granulite facies terrain, dronning maud land, antarctica |
publisher |
Cambridge University Press (CUP) |
publishDate |
2004 |
url |
http://dx.doi.org/10.1017/s0016756804009859 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0016756804009859 |
genre |
Antarc* Antarctica Dronning Maud Land |
genre_facet |
Antarc* Antarctica Dronning Maud Land |
op_source |
Geological Magazine volume 141, issue 6, page 649-660 ISSN 0016-7568 1469-5081 |
op_rights |
https://www.cambridge.org/core/terms |
op_doi |
https://doi.org/10.1017/s0016756804009859 |
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Geological Magazine |
container_volume |
141 |
container_issue |
6 |
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649 |
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660 |
_version_ |
1810494096397041664 |