The Parisian Basin

Abstract

The Parisian basin is a geographical entity whose limits are easily defined by the Armorican massif, the Massif Central, the Vosges, the Ardennes, and the English Channel. Both Burgundy and Poitou are transitional areas. The Paris basin, a more restrictive term, corresponds according to some geologists (Cavelier and Lorenz 1987) essentially to the Tertiary ‘part’ of the basin: the Île de France and surroundings. The relief of the Parisian basin results from two sets of factors: tectonic and climatic. These have operated from Triassic times until the Pleistocene and have led to the development of a geographically simple whole in its gross structure and form. However, within this framework individual natural regions (or geotypes) may be recognized. The Parisian basin is frequently considered as a model for sedimentary basins, displaying as it does, a classic framework of sedimentary formations (Pomerol 1978; Cavelier and Pomerol 1979; Cavelier et al. 1979; Pomerol and Feugueur 1986; Debrand-Passard 1995). This is evident from the geological map of France, and on the related cross-section. Indeed, the section shows the superposition of strata in a subsiding area, with a maximal thickness (3,200 m) in the Brie country. This arrangement illustrates the geometric definition of the Parisian basin, an intracratonic basin, 600 km in diameter, limited towards the west by the Armorican massif, the south by the Massif Central, the east by the Vosges, and the north-east by the Ardenno-Rhenan massif. The following geological overview is based upon the previously mentioned studies and the geological time scale. However, the analysis of the evolution of these sedimentary areas from Triassic to Neogene shows that the area named as the ‘Parisian basin’ was included in successive palaeogeographies (which were strongly influenced by adjacent seas) and overflowed across the basement regions that now act as the limits of the basin. The chronological order of the geological formations involved in the evolution of the Parisian basin according to Robin et al. (2000) is used in the following text. During the Triassic, the future Parisian basin was a gulf of the German Sea. This sea transgressed westwards and reached the meridian of Paris during the Keuper.