Deep structure of the North Biscay margin and Armorican Basin.

• Main Author: Thinon, Isabelle
• Other Authors: Bureau de Recherches Géologiques et Minières (BRGM) (BRGM), Université de Bretagne occidentale - Brest, Jean-Pierre Réhault
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 1999
• Subjects: Bay of Biscay; Rifting; Crustal thinning; Continental margin; Ocean/Continent Transition zone; Pyrenean deformation; syn-rift sediments; layer 3B; Armorican Basin; couche 3B; Transition Continent-Ocean; déformation pyrénéenne; sédiments syn-rift; Golfe de Gascogne; Bassin Armoricain; Marge continentale; amincissement crustal; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; North Atlantic
• Online Access: https://tel.archives-ouvertes.fr/tel-00605279; https://tel.archives-ouvertes.fr/tel-00605279/document; https://tel.archives-ouvertes.fr/tel-00605279/file/PhD_Thinon_1999.pdf

Papers: Thinon I. et al. (2001) Déformations pyrénéennes dans le golfe de Gascogne. C. R. Acad. Sci. Paris, 332, 561-568; Thinon I. et al. (2002) La couverture sédimentaire syn-rift de la marge Nord-Gascogne et du Bassin Armoricain (Golfe de Gascogne) : à partir de nouvelles données de sismique réflexion. BSGF, t.173, n° 6, p.515-522; Thinon I. et al. (2003) Deep structure of the Armorican Basin (Bay of Biscay): A review from Norgasis seismic reflection and refraction data. Journal of the Geological Society of London, vol.160, n°1, p.99-116(18). The formation and the evolution of the North Biscay Margin are highly linked to the opening of the Bay of Biscay, the North Atlantic Ocean and the formation of the Pyrenean. The new compilation of old and new seismic data (reflection and refraction), in correlation with results of deep drillings and continental studies (for instance on Parentis Basin and Western Approaches Basin), enabled us to define the evolution (in time and space) of the sedimentary cover; construction of regional time and depth structure and isopach maps. Four tectonic phases are identified : two during the rifting (upper Jurassic and Aptian) and two during the pyrenean compression (upper Cretaceous/Palaeocene and Eocene). "Catastrophic" tectonic and sedimentary events have affected the margin during the end of the rifting. The 80 km wide Armorican Basin is a wide Continent/Ocean Transition zone with a substratum (layer with the velocities of 7.4-7.6 km/s), interpreted as serpentinized mantle, and covered by post-rift flat-lying sediments. This Cretaceous sedimentary basin collapses at the end of the rifting or during the initiation of the oceanic accretion. The distance between the true oceanic domain and the continental domain (not thinned) is constant along the whole margin. The crustal thinning happens exclusively under the narrow continental slope; tilted blocks, situated at the foot of the continental slope, seem to have a minor role in the processes of the crustal thinning. This geometry, ...