Unravelling the geology beneath the Meso-Cenozoic sedimentary cover of the intracratonic Paris Basin -Part 3: using seismic data to decipher the structural evolution and sedimentary record of the Stephano-Permian basins

Stephanian to Permian post-orogenic basins (SPB) outcrop in several limited locations in and around the present-day French Variscan basement. Little is known about their subsurface occurrences under the post-depositional sedimentary cover. Our work intends to decipher the structural evolution of the hidden SPB in the southwestern Paris Basin, where only a few regional studies have aimed to determine their location beneath the Mesozoic sedimentary cover. Our approach is based on the reprocessing and interpretation of 36 seismic lines (1480 km) acquired by the oil industry in the 1980s. We first obtain a comprehensive view of the geometry of the SPB (Figure 1), based on (i) the interpretation of the base of the Stephano-Permian surface (lower limit) and the erosional base of the surface of the Triassic layers (upper limit) and (ii) the recognition of specific internal geometries and seismic facies. The interpreted faults are grouped into different categories according to their period of activity, with a focus on synsedimentary faults related to thickness variations of the Stephano-Permian deposits. Figure 1-The Stephano-Permian basins beneath the Mesozoic sediments of the intracratonic Paris Basin