Transpression and tectonic exhumation in the Heimefrontfjella, western orogenic front of the East African/Antarctic Orogen, revealed by quartz textures of high strain domains
The metamorphic basement of the Heimefrontfjella in western Dronning Maud Land (Antarctica) forms the western margin of the major ca. 500 million year old East African/East Antarctic Orogen that resulted from the collision of East Antarctica and greater India with the African cratons. The boundary b...
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Norwegian Polar Institute
2016
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ftjpolarres:oai:journals.openacademia.net:article/3273 2024-06-23T07:47:22+00:00 Transpression and tectonic exhumation in the Heimefrontfjella, western orogenic front of the East African/Antarctic Orogen, revealed by quartz textures of high strain domains Bauer, Wilfried Siemes, Heinrich Spaeth, Gerhard Jacobs, Joachim 2016-06-15 application/pdf text/html application/epub+zip application/xml https://polarresearch.net/index.php/polar/article/view/3273 https://doi.org/10.3402/polar.v35.25420 eng eng Norwegian Polar Institute https://polarresearch.net/index.php/polar/article/view/3273/8755 https://polarresearch.net/index.php/polar/article/view/3273/8756 https://polarresearch.net/index.php/polar/article/view/3273/8757 https://polarresearch.net/index.php/polar/article/view/3273/8758 https://polarresearch.net/index.php/polar/article/view/3273/8777 https://polarresearch.net/index.php/polar/article/view/3273 doi:10.3402/polar.v35.25420 Polar Research; Vol 35 (2016) 1751-8369 Dronning Maud Land quartz microfabrics X-ray texture goniometry shear zones mylonites info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion 2016 ftjpolarres https://doi.org/10.3402/polar.v35.25420 2024-06-13T23:33:00Z The metamorphic basement of the Heimefrontfjella in western Dronning Maud Land (Antarctica) forms the western margin of the major ca. 500 million year old East African/East Antarctic Orogen that resulted from the collision of East Antarctica and greater India with the African cratons. The boundary between the tectonothermally overprinted part of the orogen and its north-western foreland is marked by the subvertical Heimefront Shear Zone. North-west of the Heimefront Shear Zone, numerous low-angle dipping ductile thrust zones cut through the Mesoproterozoic basement. Petrographic studies, optical quartz c-axis analyses and x-ray texture goniometry of quartz-rich mylonites were used to reveal the conditions that prevailed during the deformation. Mineral assemblages in thrust mylonites show that they were formed under greenschist-facies conditions. Quartz microstructures are characteristic of the subgrain rotation regime and oblique quartz lattice preferred orientations are typical of simple shear-dominated deformation. In contrast, in the Heimefront Shear Zone, quartz textures indicate mainly flattening strain with a minor dextral rotational component. These quartz microstructures and lattice preferred orientations show signs of post-tectonic annealing following the tectonic exhumation. The spatial relation between the sub-vertical Heimefront Shear Zone and the low-angle thrusts can be explained as being the result of strain partitioning during transpressive deformation. The pure-shear component with a weak dextral strike-slip was accommodated by the Heimefront Shear Zone, whereas the north–north-west directed thrusts accommodate the simple shear component with a tectonic transport towards the foreland of the orogen.Keywords: Dronning Maud Land; quartz microfabrics; X-ray texture goniometry; shear zones; mylonites.(Published: 15 June 2016)To access the supplementary material for this article, please see the supplementary file under Article Tools, online.Citation: Polar Research 2016, 35, 25420, ... Article in Journal/Newspaper Antarc* Antarctic Antarctica Dronning Maud Land East Antarctica Polar Research Polar Research Antarctic Dronning Maud Land East Antarctica Heimefrontfjella ENVELOPE(-11.000,-11.000,-74.667,-74.667) Polar Research 35 1 25420 |
institution |
Open Polar |
collection |
Polar Research |
op_collection_id |
ftjpolarres |
language |
English |
topic |
Dronning Maud Land quartz microfabrics X-ray texture goniometry shear zones mylonites |
spellingShingle |
Dronning Maud Land quartz microfabrics X-ray texture goniometry shear zones mylonites Bauer, Wilfried Siemes, Heinrich Spaeth, Gerhard Jacobs, Joachim Transpression and tectonic exhumation in the Heimefrontfjella, western orogenic front of the East African/Antarctic Orogen, revealed by quartz textures of high strain domains |
topic_facet |
Dronning Maud Land quartz microfabrics X-ray texture goniometry shear zones mylonites |
description |
The metamorphic basement of the Heimefrontfjella in western Dronning Maud Land (Antarctica) forms the western margin of the major ca. 500 million year old East African/East Antarctic Orogen that resulted from the collision of East Antarctica and greater India with the African cratons. The boundary between the tectonothermally overprinted part of the orogen and its north-western foreland is marked by the subvertical Heimefront Shear Zone. North-west of the Heimefront Shear Zone, numerous low-angle dipping ductile thrust zones cut through the Mesoproterozoic basement. Petrographic studies, optical quartz c-axis analyses and x-ray texture goniometry of quartz-rich mylonites were used to reveal the conditions that prevailed during the deformation. Mineral assemblages in thrust mylonites show that they were formed under greenschist-facies conditions. Quartz microstructures are characteristic of the subgrain rotation regime and oblique quartz lattice preferred orientations are typical of simple shear-dominated deformation. In contrast, in the Heimefront Shear Zone, quartz textures indicate mainly flattening strain with a minor dextral rotational component. These quartz microstructures and lattice preferred orientations show signs of post-tectonic annealing following the tectonic exhumation. The spatial relation between the sub-vertical Heimefront Shear Zone and the low-angle thrusts can be explained as being the result of strain partitioning during transpressive deformation. The pure-shear component with a weak dextral strike-slip was accommodated by the Heimefront Shear Zone, whereas the north–north-west directed thrusts accommodate the simple shear component with a tectonic transport towards the foreland of the orogen.Keywords: Dronning Maud Land; quartz microfabrics; X-ray texture goniometry; shear zones; mylonites.(Published: 15 June 2016)To access the supplementary material for this article, please see the supplementary file under Article Tools, online.Citation: Polar Research 2016, 35, 25420, ... |
format |
Article in Journal/Newspaper |
author |
Bauer, Wilfried Siemes, Heinrich Spaeth, Gerhard Jacobs, Joachim |
author_facet |
Bauer, Wilfried Siemes, Heinrich Spaeth, Gerhard Jacobs, Joachim |
author_sort |
Bauer, Wilfried |
title |
Transpression and tectonic exhumation in the Heimefrontfjella, western orogenic front of the East African/Antarctic Orogen, revealed by quartz textures of high strain domains |
title_short |
Transpression and tectonic exhumation in the Heimefrontfjella, western orogenic front of the East African/Antarctic Orogen, revealed by quartz textures of high strain domains |
title_full |
Transpression and tectonic exhumation in the Heimefrontfjella, western orogenic front of the East African/Antarctic Orogen, revealed by quartz textures of high strain domains |
title_fullStr |
Transpression and tectonic exhumation in the Heimefrontfjella, western orogenic front of the East African/Antarctic Orogen, revealed by quartz textures of high strain domains |
title_full_unstemmed |
Transpression and tectonic exhumation in the Heimefrontfjella, western orogenic front of the East African/Antarctic Orogen, revealed by quartz textures of high strain domains |
title_sort |
transpression and tectonic exhumation in the heimefrontfjella, western orogenic front of the east african/antarctic orogen, revealed by quartz textures of high strain domains |
publisher |
Norwegian Polar Institute |
publishDate |
2016 |
url |
https://polarresearch.net/index.php/polar/article/view/3273 https://doi.org/10.3402/polar.v35.25420 |
long_lat |
ENVELOPE(-11.000,-11.000,-74.667,-74.667) |
geographic |
Antarctic Dronning Maud Land East Antarctica Heimefrontfjella |
geographic_facet |
Antarctic Dronning Maud Land East Antarctica Heimefrontfjella |
genre |
Antarc* Antarctic Antarctica Dronning Maud Land East Antarctica Polar Research |
genre_facet |
Antarc* Antarctic Antarctica Dronning Maud Land East Antarctica Polar Research |
op_source |
Polar Research; Vol 35 (2016) 1751-8369 |
op_relation |
https://polarresearch.net/index.php/polar/article/view/3273/8755 https://polarresearch.net/index.php/polar/article/view/3273/8756 https://polarresearch.net/index.php/polar/article/view/3273/8757 https://polarresearch.net/index.php/polar/article/view/3273/8758 https://polarresearch.net/index.php/polar/article/view/3273/8777 https://polarresearch.net/index.php/polar/article/view/3273 doi:10.3402/polar.v35.25420 |
op_doi |
https://doi.org/10.3402/polar.v35.25420 |
container_title |
Polar Research |
container_volume |
35 |
container_issue |
1 |
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25420 |
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1802651452650291200 |