How plate tectonics is recorded in chalk deposits along the eastern English Channel in Normandy (France) and Sussex (UK)

• Published in: Tectonophysics
• Main Authors: Duperret, Anne, Vandycke, Sara, Mortimore, Rory N., Genter, Albert
• Other Authors: Laboratoire Ondes et Milieux Complexes (LOMC), Centre National de la Recherche Scientifique (CNRS)-Université Le Havre Normandie (ULH), Normandie Université (NU)-Normandie Université (NU), Faculté Polytechnique, Université de Mons (UMons), University of Brighton and ChalkRock, Bureau de Recherches Géologiques et Minières (BRGM) (BRGM)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2012
• Subjects: Chalk; Meso scale fracturing; Paleostress; Lithostratigraphy; The Eastern English Channel; Anglo-Paris basin; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; North Atlantic
• Online Access: https://hal-brgm.archives-ouvertes.fr/hal-00759919; https://hal-brgm.archives-ouvertes.fr/hal-00759919/document; https://hal-brgm.archives-ouvertes.fr/hal-00759919/file/tectonophysics-2011Duperret-corrected.pdf; https://doi.org/10.1016/j.tecto.2012.01.021

International audience Intra-plate stresses that occurred in the Anglo-Paris Basin and English Channel during Upper Cretaceous and Cenozoic times are a consequence of the convergence between Eurasia and Africa and the opening of the North Atlantic area. This geodynamic re-organisation is recorded on each side of the English Channel, with the emergence of regional structures such as the the Weald-Artois anticline and the reactivation of large-scale strike-slip faults. We analyse the Anglo-Paris Basin Chalk fracture system, on each side of the eastern English Channel, using a set of 1600 meso-scale fractures data collected on coastal chalk cliffs in Normandy (NW France) and Sussex (UK). Meso-scale fracture system is precisely dated using chalk lithostratigraphy correlations within the basin. Moreover, an inversion method is used on fault slip data to evidence a paleostress chronology in the Anglo-Paris Basin. Three main Upper Cretaceous extensive events, characterized by normal faults and jointing are recorded in Normandy and two Cenozoic compressive and extensive events with strike-slip and normal faults appear in Sussex. Paleostress records vary on each part of the eastern English Channel. The meso-scale fracture system is thus used to better define the type of relationship between meso-scale and large-scale brittle deformation in the Chalk during Meso-Cenozoic. A first NE-SW extension is recorded in Normandy in relation with local anticlines structures and related to the Lower Rhine graben opening. A second event is a WNW-ESE extension of local origin in relation with the subsidence axis of the Paris Basin. The third event is a NNE-SSW extension, well marked in Normandy and related to the activation of E-W normal faults in the western approaches of the English Channel. This event is also recorded in Sussex and reactivates locally older fractures in strike-slip. The Oligocene N-S compression/E-W extension related to the Pyrenean tectonics and the last E-W extension relative to the North Sea graben opening are ...