Blocks and Hercynian inheritance
Paris Basin is a pond flexural intra-plate. Sediments méso and cénozoïques rest in conflict on a base cadomien-varisque. This base belongs to 4 domains paléogéographiques varisques, limited by weaknesses or overlappings varisques (= Hercynian, the Hercynian cycle begins in the Devonian and finishes in the Permian era):
- The Armorican domain AD (Armorican central and block cadomien), limited by the Weakness of Bray to the North;
- The domain interns ID (zone liguro-arverne and zone morvano-from Vosge), in the South and in the Southeast;
- The zone sax-thuringienne STZ, in the East, limited to the North by the Weakness of Metz and to the South by the Weakness of Vittel;
- The rhéno-Hercynian zone RHZ in the North, limited to the South by the Weakness Bray-Vittel.
The base of Mesozoic sediments of the NW of Paris Basin is bumped by 5 main lines of fracture which were remobilisées during the history of this pond.
- The weakness of the Seine (N150) and its repercussions southward that are the weaknesses of the Loire and Sennely (of orientation N-)). Northward, she goes on via a small weakness (weakness of Pavilly of orientation N70) towards the weakness of Manche (called on the ground Weakness of Fécamp-Lillebonne), weakness bends of global direction EW.
- The weakness of Bray which bounds the block cadomien in the Southwest and the rhéno-Hercynian zone in the Northeast. It is the only weakness on the profile Ecors to cross the superior crust and the MOHO (Cazes and Toreilles, on 1988). It is considered as a former Hercynian dexter ductile uncoupling. This weakness is widely inverted during the terminal Cretaceous - Eocène developing a half---aanticlinal on its margin SW. The profile ECORS shows a weakness subverticale, in light pendage towards the Northeast, which would extend until Moho. She is also affected by a dexter uncoupling. This weakness goes on in the East by the weakness of Bouchy. The weakness of Bray is sismogène with for reference the earthquake of December 1st, 1769 (IIo = VI-VII; a hour = 12 km, M = 4,8-- BRGM2008).
- The weakness of Had, being translated in the cover by the anticlinal of Gamache.
- The weakness of the Somme, the accident parallel to the weakness of Bray. She is translated in the cover by the syncline of the Somme and in the crust on 30 km of thickness. This weakness was spotted in the profile ECORS of the North of France.
- The zone of cutting the North-Artois corresponding to the forehead varisque marks the limit between the rhéno-Hercynian zone and the block of Brabant.
On its northeast edge, the block cadomien is bumped by the weakness of Lillebonne Fécamp. This weakness individualizes a sub-block towards the SW, called block of Callus. This one plays in a differential way, either by subsiding or by heightening, during the deposit of the chalk.
Deformation of the basic surface of the chalk
Weaknesses at the origin of périclines
A context compressif settles down in the upper Cretaceous, bound to the collision of the iberian, African and European patches. He asserts itself after Turonien. The direction of the compression is N - or NE-SW. Certain number of former weaknesses, as the weakness of Bray-Vittel, react transpression there. The freshly put down cover of sediment reacts by wrinkling. They are périclines.
At the level of Dieppe, the weakness of Bray do not show notorious vertical estimated rejection (maybe even set against the visible visible rejection at the heart of the Country of Bray). On the other hand, this weakness has to have a consequent, but invisible horizontal rejection because masked by the wide valley of Curve him.
Evolution morphotectonique recent of the Coal field the North Nord-Pas of Calais within the framework of the Western Europe
Study of a storage site - report BRGM
Structural inheritance and deformation of cover: tertiary wrinkling and fracturing in the West of the pond of Paris (Olivier Lacombe, Daniel Obert, on 2000)