Cenozoic folding and faulting in the south Aquitaine Basin (France): insights from combined structural and paleostress analyses

Abstract

New fieldwork, surface data (e.g. drainage network anomalies) and SPOT satellite imagery are combined with sub-surface data (seismic profiles and drill-cores) to analyse the structural setting of the south Aquitaine Basin. Cenozoic paleostresses are determined through inversion of fault slip and calcite twin data (quarries and drill cores), allowing reconstruction of the Cenozoic structural and tectonic evolution. The main tectonic event, the NNE ‘Pyrenean compression’, from the Late Cretaceous to the Oligocene, is responsible for thrusting and folding along N110° axes and strike-slip reactivation of major NNW and NE–SW faults. Some fold axes turn along NNW major wrench faults, and compression locally undergoes deviation to ENE trends. NNE extension locally occurred at anticline hinges. After a minor WNW extension, a Miocene NNW compression occurred and changed into a perpendicular ENE extension, responsible for nearly N–S normal faulting. These multiple states of stress reflect two major compressional events (NNE and NNW); their variety mainly reveals local accommodation due to numerous inherited structures, in the general context of Eurasia–Africa convergence.