Abstract: Tectonics and Sea-Level Changes: Documentation from Western European Basins

Thierry Jacquin, Valerie Goggin, Giovanni Rusciadelli, Pierre Charles de Graciansky

Quantitative subsidence analysis, coupled with a high resolution sequence stratigraphic approach, shows three imbricated orders of Transgressive/Regressive cycles illustrating an increasing effect of tectonics from the higher to the lower order frequency. These stratigraphic cycles comprise different predictive facies models, and the understanding of these models provides an important key for analysing and predicting potential reservoirs and source rocks.

Depositional Sequences, usually have 10 to 30 meters 3rd order accommodation amplitude, and can be correlated over wide areas, under different tectonic settings and depositional environments. Some of them have up to 100 meters amplitude and are clearly linked with regional tectonic events, even though they are recorded over different basins and margins.

Transgressive/Regressive Facies Cycles record n.10²m of 2nd order accommodation amplitude, mostly determined by the subsidence component, with a wavelength of lateral change of about n10²Km. It appears that the number of these cycles is similar (when recorded and preserved from later erosion) from the North Sea basins to the Tethyan basins, but their timing may vary, even inside a single basin. A possible explanation for these patterns could be the intraplate stress changes in relation to the dynamics of Atlantic and Tethyan margins.

Major Transgressive/Regressive Cycles record n.10³m of 1st order accommodation amplitude, mostly controlled by the thermal long-term basin subsidence. The wavelength of lateral change has still not been defined, but is possibly in the order of about n 10³Km. These 1st order cycles are different from the broad Paleozoic and Mesozoic-Cenozoic continental encroachment cycles.

AAPG Search and Discovery Article #90956©1995 AAPG International Convention and Exposition Meeting, Nice, France