Age and Petrogenesis of the Doros Complex, Namibia, and Implications for Early Plume-derived Melts in the Parana-Etendeka LIP
The early Cretaceous Paraná–Etendeka Large Igneous Province is attributed to the impact of the Tristan mantle plume on the base of the continental lithosphere and the associated opening of the South Atlantic Ocean during the breakup of West Gondwana. Although the geochemistry of the Paraná and Etend...
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ftubpotsdam:oai:kobv.de-opus4-uni-potsdam:55216 2024-04-28T08:38:17+00:00 Age and Petrogenesis of the Doros Complex, Namibia, and Implications for Early Plume-derived Melts in the Parana-Etendeka LIP Owen-Smith, T. M. Ashwal, L. D. Sudo, Masafumi (Dr.) Trumbull, Robert B. (Dr.) 2017-06-10 https://publishup.uni-potsdam.de/frontdoor/index/index/docId/55216 https://doi.org/10.1093/petrology/egx021 eng eng https://publishup.uni-potsdam.de/frontdoor/index/index/docId/55216 https://doi.org/10.1093/petrology/egx021 info:eu-repo/semantics/closedAccess ddc:550 Institut für Geowissenschaften article doc-type:article 2017 ftubpotsdam https://doi.org/10.1093/petrology/egx021 2024-04-09T23:38:30Z The early Cretaceous Paraná–Etendeka Large Igneous Province is attributed to the impact of the Tristan mantle plume on the base of the continental lithosphere and the associated opening of the South Atlantic Ocean during the breakup of West Gondwana. Although the geochemistry of the Paraná and Etendeka volcanic rocks has been extensively studied, there is still disagreement on the role of the mantle plume in the production of the magma types observed, because some of their primary compositions are obscured by continental crustal contamination. However, there are related plutonic rocks that preserve mantle signatures. The Doros Complex is a shallow-level mafic intrusion within the Etendeka Province of Namibia. New 39Ar/40Ar step-heating ages for Doros gabbros from this study (weighted mean of 130 ± 1 Ma; 2σ error) confirm contemporaneity with the Paraná–Etendeka magmatic event. The Doros suite yields mean ɛNd values of +5·3 ± 1·0 (1σ; n = 11), initial 87Sr/86Sr = 0·70418 ± 0·00017 (n = 11) and 206Pb/204Pb = 18·11 ± 0·06 (n = 13) at 132 Ma. The clustering of isotopic data and trends in incompatible trace element ratios indicate that all the magmas in the complex were derived from the same mantle source components, during the same melting episode. By quantitative isotopic modelling of mixing processes, we constrain the Doros parental magma to comprise 60–80% melt of a depleted asthenospheric mantle component and 20–40% melt of a more enriched, Tristan plume-derived, asthenospheric component. No lithospheric mantle component is required to explain the Doros magma compositions. The chilled margin to the complex is the only rock type that shows evidence of significant continental crustal contamination, by assimilation of the metasedimentary host-rock upon emplacement. The identification of a substantial Tristan plume component in the Doros source confirms the integral role of the deep-seated thermal anomaly in Paraná–Etendeka magmatism. We show, in addition, that the Doros suite has consistent, strong geochemical ... Article in Journal/Newspaper South Atlantic Ocean University of Potsdam: publish.UP Journal of Petrology 58 3 423 442 |
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ddc:550 Institut für Geowissenschaften Owen-Smith, T. M. Ashwal, L. D. Sudo, Masafumi (Dr.) Trumbull, Robert B. (Dr.) Age and Petrogenesis of the Doros Complex, Namibia, and Implications for Early Plume-derived Melts in the Parana-Etendeka LIP |
topic_facet |
ddc:550 Institut für Geowissenschaften |
description |
The early Cretaceous Paraná–Etendeka Large Igneous Province is attributed to the impact of the Tristan mantle plume on the base of the continental lithosphere and the associated opening of the South Atlantic Ocean during the breakup of West Gondwana. Although the geochemistry of the Paraná and Etendeka volcanic rocks has been extensively studied, there is still disagreement on the role of the mantle plume in the production of the magma types observed, because some of their primary compositions are obscured by continental crustal contamination. However, there are related plutonic rocks that preserve mantle signatures. The Doros Complex is a shallow-level mafic intrusion within the Etendeka Province of Namibia. New 39Ar/40Ar step-heating ages for Doros gabbros from this study (weighted mean of 130 ± 1 Ma; 2σ error) confirm contemporaneity with the Paraná–Etendeka magmatic event. The Doros suite yields mean ɛNd values of +5·3 ± 1·0 (1σ; n = 11), initial 87Sr/86Sr = 0·70418 ± 0·00017 (n = 11) and 206Pb/204Pb = 18·11 ± 0·06 (n = 13) at 132 Ma. The clustering of isotopic data and trends in incompatible trace element ratios indicate that all the magmas in the complex were derived from the same mantle source components, during the same melting episode. By quantitative isotopic modelling of mixing processes, we constrain the Doros parental magma to comprise 60–80% melt of a depleted asthenospheric mantle component and 20–40% melt of a more enriched, Tristan plume-derived, asthenospheric component. No lithospheric mantle component is required to explain the Doros magma compositions. The chilled margin to the complex is the only rock type that shows evidence of significant continental crustal contamination, by assimilation of the metasedimentary host-rock upon emplacement. The identification of a substantial Tristan plume component in the Doros source confirms the integral role of the deep-seated thermal anomaly in Paraná–Etendeka magmatism. We show, in addition, that the Doros suite has consistent, strong geochemical ... |
format |
Article in Journal/Newspaper |
author |
Owen-Smith, T. M. Ashwal, L. D. Sudo, Masafumi (Dr.) Trumbull, Robert B. (Dr.) |
author_facet |
Owen-Smith, T. M. Ashwal, L. D. Sudo, Masafumi (Dr.) Trumbull, Robert B. (Dr.) |
author_sort |
Owen-Smith, T. M. |
title |
Age and Petrogenesis of the Doros Complex, Namibia, and Implications for Early Plume-derived Melts in the Parana-Etendeka LIP |
title_short |
Age and Petrogenesis of the Doros Complex, Namibia, and Implications for Early Plume-derived Melts in the Parana-Etendeka LIP |
title_full |
Age and Petrogenesis of the Doros Complex, Namibia, and Implications for Early Plume-derived Melts in the Parana-Etendeka LIP |
title_fullStr |
Age and Petrogenesis of the Doros Complex, Namibia, and Implications for Early Plume-derived Melts in the Parana-Etendeka LIP |
title_full_unstemmed |
Age and Petrogenesis of the Doros Complex, Namibia, and Implications for Early Plume-derived Melts in the Parana-Etendeka LIP |
title_sort |
age and petrogenesis of the doros complex, namibia, and implications for early plume-derived melts in the parana-etendeka lip |
publishDate |
2017 |
url |
https://publishup.uni-potsdam.de/frontdoor/index/index/docId/55216 https://doi.org/10.1093/petrology/egx021 |
genre |
South Atlantic Ocean |
genre_facet |
South Atlantic Ocean |
op_relation |
https://publishup.uni-potsdam.de/frontdoor/index/index/docId/55216 https://doi.org/10.1093/petrology/egx021 |
op_rights |
info:eu-repo/semantics/closedAccess |
op_doi |
https://doi.org/10.1093/petrology/egx021 |
container_title |
Journal of Petrology |
container_volume |
58 |
container_issue |
3 |
container_start_page |
423 |
op_container_end_page |
442 |
_version_ |
1797569503076286464 |