The wide-angle seismic image of a complex rifted margin, offshore North Namibia: Implications for the tectonics of continental breakup
Voluminous magmatism during the South Atlantic opening has been considered as a classical example for plume related continental breakup. We present a study of the crustal structure around Walvis Ridge, near the intersection with the African margin. Two wide-angle seismic profiles were acquired. One...
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Online Access: | https://epic.awi.de/id/eprint/41117/ http://www.sciencedirect.com/science/article/pii/S004019511630230X https://hdl.handle.net/10013/epic.50442 |
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ftawi:oai:epic.awi.de:41117 2024-09-15T18:36:31+00:00 The wide-angle seismic image of a complex rifted margin, offshore North Namibia: Implications for the tectonics of continental breakup Planert, Lars Behrmann, Jan Jokat, Wilfried Fromm, Tanja Ryberg, Trond Weber, Michael Haberland, Christian 2017-10-02 https://epic.awi.de/id/eprint/41117/ http://www.sciencedirect.com/science/article/pii/S004019511630230X https://hdl.handle.net/10013/epic.50442 unknown ELSEVIER SCIENCE BV Planert, L. , Behrmann, J. , Jokat, W. orcid:0000-0002-7793-5854 , Fromm, T. orcid:0000-0003-2650-4090 , Ryberg, T. , Weber, M. and Haberland, C. (2017) The wide-angle seismic image of a complex rifted margin, offshore North Namibia: Implications for the tectonics of continental breakup , Tectonophysics, 716 , pp. 130-148 . doi:10.1016/j.tecto.2016.06.024 <https://doi.org/10.1016/j.tecto.2016.06.024> , hdl:10013/epic.50442 EPIC3Tectonophysics, ELSEVIER SCIENCE BV, 716, pp. 130-148, ISSN: 0040-1951 Article isiRev 2017 ftawi https://doi.org/10.1016/j.tecto.2016.06.024 2024-06-24T04:14:20Z Voluminous magmatism during the South Atlantic opening has been considered as a classical example for plume related continental breakup. We present a study of the crustal structure around Walvis Ridge, near the intersection with the African margin. Two wide-angle seismic profiles were acquired. One is oriented NNW-SSE, following the continent-ocean transition and crossing Walvis Ridge. A second amphibious profile runs NW-SE from the Angola Basin into continental Namibia. At the continent-ocean boundary (COB) the mafic crust beneath Walvis Ridge is up to 33 km thick, with a pronounced high-velocity lower crustal body. Towards the south there is a smooth transition to 20-25 km thick crust underlying the {COB} in the Walvis Basin, with a similar velocity structure, indicating a gabbroic lower crust with associated cumulates at the base. The northern boundary of Walvis Ridge towards the Angola Basin shows a sudden change to oceanic crust only 4-6 km thick, coincident with the projection of the Florianopolis Fracture Zone, one of the most prominent tectonic features of the South Atlantic ocean basin. In the amphibious profile the {COB} is defined by a sharp transition from oceanic to rifted continental crust, with a magmatic overprint landward of the intersection of Walvis Ridge with the Namibian margin. The continental crust beneath the Congo Craton is 40 km thick, shoaling to 35 km further SE. The velocity models show that massive high-velocity gabbroic intrusives are restricted to a narrow zone directly underneath Walvis Ridge and the {COB} in the south. This distribution of rift-related magmatism is not easily reconciled with models of continental breakup following the establishment of a large, axially symmetric plume in the Earth´s mantle. Rift-related lithospheric stretching and associated transform faulting play an overriding role in locating magmatism, dividing the margin in a magma-dominated southern and an essentially amagmatic northern segment. Article in Journal/Newspaper South Atlantic Ocean Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) Tectonophysics 716 130 148 |
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Open Polar |
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Alfred Wegener Institute for Polar- and Marine Research (AWI): ePIC (electronic Publication Information Center) |
op_collection_id |
ftawi |
language |
unknown |
description |
Voluminous magmatism during the South Atlantic opening has been considered as a classical example for plume related continental breakup. We present a study of the crustal structure around Walvis Ridge, near the intersection with the African margin. Two wide-angle seismic profiles were acquired. One is oriented NNW-SSE, following the continent-ocean transition and crossing Walvis Ridge. A second amphibious profile runs NW-SE from the Angola Basin into continental Namibia. At the continent-ocean boundary (COB) the mafic crust beneath Walvis Ridge is up to 33 km thick, with a pronounced high-velocity lower crustal body. Towards the south there is a smooth transition to 20-25 km thick crust underlying the {COB} in the Walvis Basin, with a similar velocity structure, indicating a gabbroic lower crust with associated cumulates at the base. The northern boundary of Walvis Ridge towards the Angola Basin shows a sudden change to oceanic crust only 4-6 km thick, coincident with the projection of the Florianopolis Fracture Zone, one of the most prominent tectonic features of the South Atlantic ocean basin. In the amphibious profile the {COB} is defined by a sharp transition from oceanic to rifted continental crust, with a magmatic overprint landward of the intersection of Walvis Ridge with the Namibian margin. The continental crust beneath the Congo Craton is 40 km thick, shoaling to 35 km further SE. The velocity models show that massive high-velocity gabbroic intrusives are restricted to a narrow zone directly underneath Walvis Ridge and the {COB} in the south. This distribution of rift-related magmatism is not easily reconciled with models of continental breakup following the establishment of a large, axially symmetric plume in the Earth´s mantle. Rift-related lithospheric stretching and associated transform faulting play an overriding role in locating magmatism, dividing the margin in a magma-dominated southern and an essentially amagmatic northern segment. |
format |
Article in Journal/Newspaper |
author |
Planert, Lars Behrmann, Jan Jokat, Wilfried Fromm, Tanja Ryberg, Trond Weber, Michael Haberland, Christian |
spellingShingle |
Planert, Lars Behrmann, Jan Jokat, Wilfried Fromm, Tanja Ryberg, Trond Weber, Michael Haberland, Christian The wide-angle seismic image of a complex rifted margin, offshore North Namibia: Implications for the tectonics of continental breakup |
author_facet |
Planert, Lars Behrmann, Jan Jokat, Wilfried Fromm, Tanja Ryberg, Trond Weber, Michael Haberland, Christian |
author_sort |
Planert, Lars |
title |
The wide-angle seismic image of a complex rifted margin, offshore North Namibia: Implications for the tectonics of continental breakup |
title_short |
The wide-angle seismic image of a complex rifted margin, offshore North Namibia: Implications for the tectonics of continental breakup |
title_full |
The wide-angle seismic image of a complex rifted margin, offshore North Namibia: Implications for the tectonics of continental breakup |
title_fullStr |
The wide-angle seismic image of a complex rifted margin, offshore North Namibia: Implications for the tectonics of continental breakup |
title_full_unstemmed |
The wide-angle seismic image of a complex rifted margin, offshore North Namibia: Implications for the tectonics of continental breakup |
title_sort |
wide-angle seismic image of a complex rifted margin, offshore north namibia: implications for the tectonics of continental breakup |
publisher |
ELSEVIER SCIENCE BV |
publishDate |
2017 |
url |
https://epic.awi.de/id/eprint/41117/ http://www.sciencedirect.com/science/article/pii/S004019511630230X https://hdl.handle.net/10013/epic.50442 |
genre |
South Atlantic Ocean |
genre_facet |
South Atlantic Ocean |
op_source |
EPIC3Tectonophysics, ELSEVIER SCIENCE BV, 716, pp. 130-148, ISSN: 0040-1951 |
op_relation |
Planert, L. , Behrmann, J. , Jokat, W. orcid:0000-0002-7793-5854 , Fromm, T. orcid:0000-0003-2650-4090 , Ryberg, T. , Weber, M. and Haberland, C. (2017) The wide-angle seismic image of a complex rifted margin, offshore North Namibia: Implications for the tectonics of continental breakup , Tectonophysics, 716 , pp. 130-148 . doi:10.1016/j.tecto.2016.06.024 <https://doi.org/10.1016/j.tecto.2016.06.024> , hdl:10013/epic.50442 |
op_doi |
https://doi.org/10.1016/j.tecto.2016.06.024 |
container_title |
Tectonophysics |
container_volume |
716 |
container_start_page |
130 |
op_container_end_page |
148 |
_version_ |
1810480179339853824 |