Failles transverses dans le fossé rhénan

PosterL'étude du fossé rhénan dans le cadre du projet européen INTERREG IV Rhin Supérieur, mené en collaboration avec l'Allemagne et la Suisse, permet d'apporter des connaissances nouvelles sur la structure du fossé rhénan. Un modèle géologique 3D sur l'ensemble du graben du Rhin est en cours d'élaboration. Ce travail s'appuie sur le retraitement et l'homogénéisation de plus de 5500 kms de données de sismique réflexion et l'utilisation de plus de 1800 forages. La construction du schéma structural entre Wissembourg et Sélestat est bien avancée et permet de livrer les premières analyses. De nombreuses structures tectoniques décrochantes ont été observées dans cette zone nord et centrale de la région Alsace, comme des structures en fleurs négatives affectant l'ensemble de la pile sédimentaire. Le schéma structural de cette zone permet aussi de caractériser de nombreuses failles de direction N350 à N10. Il met de plus en évidence la présence de deux failles de direction N70-N80 situées au nord de Strasbourg et au nord de Sélestat. Ces deux failles affectant les séries syn et post rift dans le fossé rhénan semblent être le prolongement de deux structures varisques de direction N70-N80 connues à l'affleurement de part et d'autre du fossé (faille transformante de Lalaye-Lubine en France et son pendant en Allemagne la faille transformante de Baden-Baden). Cette observation montre que les deux failles transformantes reconnues à l'affleurement se prolongeraient dans le fossé rhénan, confirmant le rôle important de l'héritage varisque dans la structure tertiaire du fossé rhénan

Report on ICDP Deep Dust workshops: probing continental climate of the late Paleozoic icehouse–greenhouse transition and beyond

Chamberlin and Salisbury's assessment of the Permian a century ago captured the essence of the period: it is an interval of extremes yet one sufficiently recent to have affected a biosphere with near-modern complexity. The events of the Permian - the orogenic episodes, massive biospheric turnovers, both icehouse and greenhouse antitheses, and Mars-analog lithofacies - boggle the imagination and present us with great opportunities to explore Earth system behavior. The ICDP-funded workshops dubbed "Deep Dust," held in Oklahoma (USA) in March 2019 (67 participants from nine countries) and Paris (France) in January 2020 (33 participants from eight countries), focused on clarifying the scientific drivers and key sites for coring continuous sections of Permian continental (loess, lacustrine, and associated) strata that preserve high-resolution records. Combined, the two workshops hosted a total of 91 participants representing 14 countries, with broad expertise. Discussions at Deep Dust 1.0 (USA) focused on the primary research questions of paleoclimate, paleoenvironments, and paleoecology of icehouse collapse and the run-up to the Great Dying and both the modern and Permian deep microbial biosphere. Auxiliary science topics included tectonics, induced seismicity, geothermal energy, and planetary science. Deep Dust 1.0 also addressed site selection as well as scientific approaches, logistical challenges, and broader impacts and included a mid-workshop field trip to view the Permian of Oklahoma. Deep Dust 2.0 focused specifically on honing the European target. The Anadarko Basin (Oklahoma) and Paris Basin (France) represent the most promising initial targets to capture complete or near-complete stratigraphic coverage through continental successions that serve as reference points for western and eastern equatorial Pangaea. © 2020 Copernicus GmbH. All rights reserved

Report on ICDP Deep Dust workshops: probing continental climate of the late Paleozoic icehouse–greenhouse transition and beyond

Chamberlin and Salisbury's assessment of the Permian a century ago captured the essence of the period: it is an interval of extremes yet one sufficiently recent to have affected a biosphere with near-modern complexity. The events of the Permian - the orogenic episodes, massive biospheric turnovers, both icehouse and greenhouse antitheses, and Mars-analog lithofacies - boggle the imagination and present us with great opportunities to explore Earth system behavior. The ICDP-funded workshops dubbed "Deep Dust," held in Oklahoma (USA) in March 2019 (67 participants from nine countries) and Paris (France) in January 2020 (33 participants from eight countries), focused on clarifying the scientific drivers and key sites for coring continuous sections of Permian continental (loess, lacustrine, and associated) strata that preserve high-resolution records. Combined, the two workshops hosted a total of 91 participants representing 14 countries, with broad expertise. Discussions at Deep Dust 1.0 (USA) focused on the primary research questions of paleoclimate, paleoenvironments, and paleoecology of icehouse collapse and the run-up to the Great Dying and both the modern and Permian deep microbial biosphere. Auxiliary science topics included tectonics, induced seismicity, geothermal energy, and planetary science. Deep Dust 1.0 also addressed site selection as well as scientific approaches, logistical challenges, and broader impacts and included a mid-workshop field trip to view the Permian of Oklahoma. Deep Dust 2.0 focused specifically on honing the European target. The Anadarko Basin (Oklahoma) and Paris Basin (France) represent the most promising initial targets to capture complete or near-complete stratigraphic coverage through continental successions that serve as reference points for western and eastern equatorial Pangaea.This research has been supported by the ICDP (DeepDust2019 grant).Ye

Les bassins carbonifères-permiens et leur couverture méso-cénozoïque - Mise à jour des connaissances, applications et perspectives

This HDR thesis highlights my research work over the last 15 years on Carboniferous-Permian sedimentary basins and their Meso-Cenozoic cover in France. (i) A first methodological section presents the reprocessing and interpretation of industrial seismic reflection profiles. These profiles, coupled with appropriate borehole data, are crucial for imaging and understanding the mode of formation and evolution of these basins and their cover over geological time. (ii) A second section describes my work on the Carboniferous-Permian basins, at the heart of my manuscript. Firstly, I describe their tectonic and sedimentary characteristics (location under cover, depth, thickness, temporal setting, structural style, mode of filling). I then show, based on kinematic scenarios, how they record the syn- to post-orogenic Variscan transition (syn-orogenic: Hauts-de-France coal basin; syn- to post-orogenic transition: Lorraine coal basin; post-orogenic: basins of the northern Massif Central and SW Paris Basin). (iii) Using the same subsurface data (seismic profiles and boreholes, see section 1), the third section presents my research on their Meso-Cenozoic sedimentary cover, based on my work in the Paris Basin and Rhine Graben. Using updated structural schemes, I describe the large-scale impact of structures on reservoirs/aquifers, and their deformation in response to geodynamic events of the West European plate. (iv) In the final section, I present my research prospects, emphasizing the need to continue updating our knowledge of Carboniferous-Permian sedimentary basins and their cover, through new case studies or new methodological approaches. Indeed, the current energy transition requires us to understand our subsurface better, in order to define and respond to its new uses (geothermal energy, hydrogeology, natural helium, deep storage, etc.).Ce mémoire d’HDR met en lumière mes travaux de recherche au cours des 15 dernières années sur les bassins sédimentaires carbonifères-permiens et leur couverture méso-cénozoïque sur le territoire métropolitain. (i) Un premier volet méthodologique présente le retraitement et l’interprétation de profils sismiques réflexions industriels. Véritable matière de mon travail, ces profils couplés aux données de forages adéquates sont cruciaux pour imager et comprendre le mode de formation et l’évolution de ces bassins et de leur couverture au cours des temps géologiques. (ii) Un second volet expose mes travaux sur les bassins carbonifères-permiens, au cœur de mon manuscrit. Il s’agit en premier lieu de préciser leurs caractéristiques tectoniques et sédimentaires (localisation sous couverture, profondeur, épaisseur, calage temporel, style structural, mode de remplissage). Je montre ensuite, sur la base de scénarios cinématiques, comment ils enregistrent la transition syn- à post-orogénique varisque (syn-orogénique : bassin houiller des Hauts-de-France ; transition syn à post-orogénique : bassin houiller lorrain ; post-orogénique : bassins du nord du Massif Central et du SO du bassin de Paris). (iii) En utilisant les mêmes données de subsurface (profils sismiques et forages, cf. volet 1), le troisième volet présente mes recherches sur leur couverture sédimentaire méso-cénozoïque, à l’exemple de mes travaux dans le bassin de Paris et le fossé Rhénan. Sur la base de schémas structuraux mis à jour, je précise l’impact grande maille des structures sur les réservoirs/aquifères, et leur déformation en réponses aux événements géodynamiques subis par la plaque ouest-européenne. (iv) Je présente dans une dernière partie mes perspectives de recherches, en insistant sur la nécessité de continuer de mettre à jour la connaissance sur les bassins sédimentaires carbonifères-permiens et leur couverture, à travers de nouveaux cas d’études ou des nouvelles approches méthodologiques. En effet, la transition énergétique en cours nous impose de mieux connaitre notre sous-sol, afin de définir et répondre à ses nouveaux usages (géothermie, hydrogéologie, hélium naturel, stockage profond…)

The 3.9 km-thick Carboniferous-Permian Brécy Basin (SW Paris Basin, France), a missing link between late Variscan basins in southern and northern Europe

International audienceFrom the end of the Carboniferous onwards, the over-thickened and hot Variscan crust collapsed (late-orogenic collapse), accompanied by the rise of high-grade metamorphic domes along lowangle detachment faults and the development of mainly half-graben or pull-apart type asymmetricintramountain coal basins. These Carboniferous-Permian late orogenic basins widely developed around 300 Ma and were filled with siliciclastic continental material, accompanied by a widespread intrusive and extrusive magmatic activity. These basins crop out in the internal parts of the belt south of the Variscan Front in several limited locations in and around the Variscan basement of Western Europe (Massif Central, Vosges-Black Forest, Alps, Harz). They occur as small isolated and disconnected “basins” with incomplete sedimentary series. Their present-day area does not reflect their initial extent and thickness, which can be explored by studying their subsurface prolongation beneath their Meso-Cenozoic sedimentary covers.We propose a geological overview of the late Variscan Carboniferous-Permian Brécy basin (SW Paris basin, France), based on the reprocessing and interpretation of vintage seismic lines and related deep boreholes. We aim (i) to discuss its sedimentary filling, which is hidden beneath theMeso-Cenozoic cover of the Paris basin, (ii) to present thickness maps of its 3.9 km-thick sedimentary filling, and (iii) to describe its structural extensional features related to a syn- to postrift tectonic scenario. We finally compared our new results to other Carboniferous-Permian deposits in France (to discuss its lateral correlation with neighboring basins) and northwest Europe, suggesting that the Brécy Basin may represent - due to its thickness and location - a missing link between late Variscan basins in southern and northern Europe

The 3.9 km-thick Carboniferous-Permian Brécy Basin (SW Paris Basin, France), a missing link between late Variscan basins in southern and northern Europe

International audienceFrom the end of the Carboniferous onwards, the over-thickened and hot Variscan crust collapsed (late-orogenic collapse), accompanied by the rise of high-grade metamorphic domes along lowangle detachment faults and the development of mainly half-graben or pull-apart type asymmetricintramountain coal basins. These Carboniferous-Permian late orogenic basins widely developed around 300 Ma and were filled with siliciclastic continental material, accompanied by a widespread intrusive and extrusive magmatic activity. These basins crop out in the internal parts of the belt south of the Variscan Front in several limited locations in and around the Variscan basement of Western Europe (Massif Central, Vosges-Black Forest, Alps, Harz). They occur as small isolated and disconnected “basins” with incomplete sedimentary series. Their present-day area does not reflect their initial extent and thickness, which can be explored by studying their subsurface prolongation beneath their Meso-Cenozoic sedimentary covers.We propose a geological overview of the late Variscan Carboniferous-Permian Brécy basin (SW Paris basin, France), based on the reprocessing and interpretation of vintage seismic lines and related deep boreholes. We aim (i) to discuss its sedimentary filling, which is hidden beneath theMeso-Cenozoic cover of the Paris basin, (ii) to present thickness maps of its 3.9 km-thick sedimentary filling, and (iii) to describe its structural extensional features related to a syn- to postrift tectonic scenario. We finally compared our new results to other Carboniferous-Permian deposits in France (to discuss its lateral correlation with neighboring basins) and northwest Europe, suggesting that the Brécy Basin may represent - due to its thickness and location - a missing link between late Variscan basins in southern and northern Europe