Synsedimentary Polygonal Faults System in Tight Chalk: Multiscale evidence from outcrop, Flamborough Head (UK)

Abstract : (200 words max) The Flamborough Head chalk cliffs (Yorkshire, UK) are an outstanding outcrop of once deeply-buried tight-chalk and are likely to be representative of sub-surface chalk reservoirs in nearby onshore and offshore regions, i.e. the North Sea. These chalk outcrops display a very complex fracture network, which has been widely described and which has been traditionally interpreted as the result of polyphased extensional tectonic events due to their random distribution. High-resolution drone imaging performed on the platform revealed the overall organization of the fault network displaying irregular polygonal cellular patterns. They likely correspond to polygonal fault systems (PFS) with an isotropic horizontal state of stress during early compaction. Field observations allowed to evidence the synsedimentary nature of these normal faults involved in the PFS, supporting the fact that faulting occurred when the sediment was in a gel-like state shortly after deposition. Different orders of magnitude of imbricate polygonal fault systems were identified, with nested polygon cells of centimeter to hectometer scale. The Oligocene transpressive tectonic events resulted in the reactivation of preferential orientations of the PFS as tectonic stylolites (with horizontal peaks), highlighting the importance of PFS in fluid transport.
Type de document :
Communication dans un congrès
79th EAGE Conference, Jun 2017, Paris, France. pp.12 - 15
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https://hal-brgm.archives-ouvertes.fr/hal-01481936
Contributeur : Cécile Allanic <>
Soumis le : vendredi 3 mars 2017 - 09:46:03
Dernière modification le : vendredi 23 juin 2017 - 16:03:41

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  • HAL Id : hal-01481936, version 1

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Ophélie Faÿ-Gomord, Cécile Allanic, Michaël Verbiest, Eric Lasseur, Rudy Swennen, et al.. Synsedimentary Polygonal Faults System in Tight Chalk: Multiscale evidence from outcrop, Flamborough Head (UK). 79th EAGE Conference, Jun 2017, Paris, France. pp.12 - 15. 〈hal-01481936〉

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