Cambrian–early Ordovician volcanism across the South Armorican and Occitan domains of the Variscan Belt in France: Continental break-up and rifting of the northern Gondwana margin
The Cambrian–lower Ordovician volcanic units of the South Armorican and Occitan domains are analysed in a tectonostratigraphic survey of the French Variscan Belt. The South Armorican lavas consist of continental tholeiites in middle Cambrian–Furongian sequences related to continental break-up. A sig...
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Elsevier
2017-01-01
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| Series: | Geoscience Frontiers |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S1674987116300196 |
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| author | André Pouclet J. Javier Álvaro Jacques-Marie Bardintzeff Andrés Gil Imaz Eric Monceret Daniel Vizcaïno |
| author_facet | André Pouclet J. Javier Álvaro Jacques-Marie Bardintzeff Andrés Gil Imaz Eric Monceret Daniel Vizcaïno |
| author_sort | André Pouclet |
| collection | DOAJ |
| description | The Cambrian–lower Ordovician volcanic units of the South Armorican and Occitan domains are analysed in a tectonostratigraphic survey of the French Variscan Belt. The South Armorican lavas consist of continental tholeiites in middle Cambrian–Furongian sequences related to continental break-up. A significant volcanic activity occurred in the Tremadocian, dominated by crustal melted rhyolitic lavas and initial rifting tholeiites. The Occitan lavas are distributed into five volcanic phases: (1) basal Cambrian rhyolites, (2) upper lower Cambrian Mg-rich tholeiites close to N-MORBs but crustal contaminated, (3) upper lower–middle Cambrian continental tholeiites, (4) Tremadocian rhyolites, and (5) upper lower Ordovician initial rift tholeiites. A rifting event linked to asthenosphere upwelling took place in the late early Cambrian but did not evolve. It renewed in the Tremadocian with abundant crustal melting due to underplating of mixed asthenospheric and lithospheric magmas. This main tectono-magmatic continental rift is termed the “Tremadocian Tectonic Belt” underlined by a chain of rhyolitic volcanoes from Occitan and South Armorican domains to Central Iberia. It evolved with the setting of syn-rift coarse siliciclastic deposits overlain by post-rift deep water shales in a suite of sedimentary basins that forecasted the South Armorican–Medio-European Ocean as a part of the Palaeotethys Ocean. |
| first_indexed | 2024-03-12T18:27:53Z |
| format | Article |
| id | doaj.art-467a83b89268408a9c6e522407704b23 |
| institution | Directory Open Access Journal |
| issn | 1674-9871 |
| language | English |
| last_indexed | 2024-03-12T18:27:53Z |
| publishDate | 2017-01-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Geoscience Frontiers |
| spelling | doaj.art-467a83b89268408a9c6e522407704b232023-08-02T08:26:55ZengElsevierGeoscience Frontiers1674-98712017-01-0181256410.1016/j.gsf.2016.03.002Cambrian–early Ordovician volcanism across the South Armorican and Occitan domains of the Variscan Belt in France: Continental break-up and rifting of the northern Gondwana marginAndré Pouclet0J. Javier Álvaro1Jacques-Marie Bardintzeff2Andrés Gil Imaz3Eric Monceret4Daniel Vizcaïno53 rue des Foulques, 85560 Longeville-sur-mer, FranceInstituto de Geociencias (CSIC-UCM), c/José Antonio Novais 12, 28040 Madrid, SpainVolcanology and Planetology, UMR CNRS 8148 GEOPS, University of Paris-Saclay, 91405 Orsay, FranceDepartamento Ciencias de la Tierra, Universidad de Zaragoza, 50009 Zaragoza, Spain18 rue des Pins, 11570 Cazilhac, France7 Jean-Baptiste Chardin, Maquens, 11090 Carcassonne, FranceThe Cambrian–lower Ordovician volcanic units of the South Armorican and Occitan domains are analysed in a tectonostratigraphic survey of the French Variscan Belt. The South Armorican lavas consist of continental tholeiites in middle Cambrian–Furongian sequences related to continental break-up. A significant volcanic activity occurred in the Tremadocian, dominated by crustal melted rhyolitic lavas and initial rifting tholeiites. The Occitan lavas are distributed into five volcanic phases: (1) basal Cambrian rhyolites, (2) upper lower Cambrian Mg-rich tholeiites close to N-MORBs but crustal contaminated, (3) upper lower–middle Cambrian continental tholeiites, (4) Tremadocian rhyolites, and (5) upper lower Ordovician initial rift tholeiites. A rifting event linked to asthenosphere upwelling took place in the late early Cambrian but did not evolve. It renewed in the Tremadocian with abundant crustal melting due to underplating of mixed asthenospheric and lithospheric magmas. This main tectono-magmatic continental rift is termed the “Tremadocian Tectonic Belt” underlined by a chain of rhyolitic volcanoes from Occitan and South Armorican domains to Central Iberia. It evolved with the setting of syn-rift coarse siliciclastic deposits overlain by post-rift deep water shales in a suite of sedimentary basins that forecasted the South Armorican–Medio-European Ocean as a part of the Palaeotethys Ocean.http://www.sciencedirect.com/science/article/pii/S1674987116300196Gondwana marginCambro–Ordovician volcanic activityContinental tholeiiteRheic OceanMiddle-European OceanPalaeotethys Ocean |
| spellingShingle | André Pouclet J. Javier Álvaro Jacques-Marie Bardintzeff Andrés Gil Imaz Eric Monceret Daniel Vizcaïno Cambrian–early Ordovician volcanism across the South Armorican and Occitan domains of the Variscan Belt in France: Continental break-up and rifting of the northern Gondwana margin Geoscience Frontiers Gondwana margin Cambro–Ordovician volcanic activity Continental tholeiite Rheic Ocean Middle-European Ocean Palaeotethys Ocean |
| title | Cambrian–early Ordovician volcanism across the South Armorican and Occitan domains of the Variscan Belt in France: Continental break-up and rifting of the northern Gondwana margin |
| title_full | Cambrian–early Ordovician volcanism across the South Armorican and Occitan domains of the Variscan Belt in France: Continental break-up and rifting of the northern Gondwana margin |
| title_fullStr | Cambrian–early Ordovician volcanism across the South Armorican and Occitan domains of the Variscan Belt in France: Continental break-up and rifting of the northern Gondwana margin |
| title_full_unstemmed | Cambrian–early Ordovician volcanism across the South Armorican and Occitan domains of the Variscan Belt in France: Continental break-up and rifting of the northern Gondwana margin |
| title_short | Cambrian–early Ordovician volcanism across the South Armorican and Occitan domains of the Variscan Belt in France: Continental break-up and rifting of the northern Gondwana margin |
| title_sort | cambrian early ordovician volcanism across the south armorican and occitan domains of the variscan belt in france continental break up and rifting of the northern gondwana margin |
| topic | Gondwana margin Cambro–Ordovician volcanic activity Continental tholeiite Rheic Ocean Middle-European Ocean Palaeotethys Ocean |
| url | http://www.sciencedirect.com/science/article/pii/S1674987116300196 |
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