KEUPER STRATIGRAPHIC CYCLES IN THE PARIS BASIN AND COMPARISON WITH CYCLES IN OTHER PERITETHYAN BASINS (GERMAN BASIN AND BRESSE-JURA BASIN)

High-resolution sequence stratigraphy of the Keuper, Paris Basin, is u sed to establish correlations between the basin-centre evaporite serie s and the basin-margin clastics series. The high-resolution correlatio ns show stratigraphic cycle geometries. The Keuper consists of five mi nor base-level cycles which occur in the upper portion of the Scythian -Carnian major base-level cycle and the lower part of the Carnian-Lias sic major base-level cycle. The maximum relative rate of subsidence fo r the base-level fall phase of the Scythian-Carnian major cycle occurs in the eastern part of the Paris Basin. During the base-level rise ph ase of the Carnian-Liassic major cycle, the area of highest rate of su bsidence shifted westwards and northwards. This shift records the firs t occurrence of an independent Paris Basin which was no longer merely the western margin of the German Basin. Two phases of tectonic movemen t influenced the distribution of the depocentres. The first is recorde d in the 'Marnes irisees inferieures' deposits. Faulting controlled ev aporite sedimentation and sequence geometries by creating areas of sub sidence where halite could accumulate. The second, within the 'Marnes irisees superieures', induced a general westward and northward tilt of the basin. Concurrent migration of depocentres to the west and north produced an intra-'Marnes irisees superieures' truncation. Comparison of the stratigraphic records of the Paris Basin and of other Triassic Peritethyan basins (German Basin, Bresse-Jura Basin and South-East Bas in) reveals numerous similarities. The coastal onlap curve of the Germ an Keuper (Aigner and Bachmann, 1992) exhibits many similarities with the sequence evolution of the Paris Basin. But the Triassic succession is more complete in the German Basin and more cycles are observed. Th e major difference between these two basins during the Keuper is that the 'Marnes irisees inferieures' minor base-level cycle does not occur in the German Basin. In the Bresse-Jura Basin, the major difference c oncerns the Lettenkohle. One minor base-level cycle is recorded in the Paris Basin while no cycle is observed in the Bresse-Jura Basin.