Published online by Cambridge University Press: 01 May 2009
There are two thrust systems in the Southwest Pyrenees: a NW-SE trending, thin-skin system exposed in the post-Triassic cover and a larger, thick-skin system of NE-SW thrusts in the Palaeozoic basement. The ‘cover’ thrust system propagated and migrated both southward and westward in response to the non-orthogonal collision of Iberia with Europe during Palaeogene mountain building. The ‘basement’ thrust system is interpreted to be a longer-lived structure, initiated during the extensional tectonic regime in mid Cretaceous time, and inverted during the main episode of Pyrenean collision. A model in which interaction of the two thrust systems controlled the timing and magnitude of thrust-induced, flexural subsidence is presented. The development of the basement thrust system caused regional subsidence along the South Pyrenean foreland margin that was subsequently halted by local uplift associated with the west-migratingcover thrust system.