Subsidence history of the Aquitaine basin determined from subsidence curves

The subsidence history of the Aquitaine basin has been determined from deep exploratory well data. The contribution of sediment loading to the subsidence has been evaluated and removed, including corrections for effects of compaction, water depth and changes of sea-level but not of flexural rigidity of the lithosphere. The tectonic subsidence curves obtained indicate that the basin underwent two periods of subsidence acceleration in the Trias–Early Lias and Late Jurassic–Early Cretaceous. They are interpreted in relation to the displacements of Iberia with respect to Europe as two periods of extension followed by periods of passive subsidence due to conductive cooling of the lithosphere; the formation of the ‘flysch trough’ in the southern part of the basin is then discussed.