Syndepositional faulting in the Grès d'Annot Formation, SE France: high-resolution kinematic analysis and stratigraphic response to growth faulting

Abstract

Abstract The presence of syndepositional reservoir scale faulting in the Grès d'Annot Formation adds an additional level of complexity in understanding the stratigraphic architecture of these, and potentially other, deep-water reservoir successions. A series of five synsedimentary faults have been characterized in relation to the high-resolution depositional framework of the Annot deep-water sandstone, faults that were active at the time of deposition of the Grès d'Annot, influencing both stratigraphic architecture and depositional processes. The five faults have normal throw, strike NE-SW (perpendicular to the regional palaeocurrent direction), and have maximum syndepositional throws of between 5 and 30m (sub-seismic-resolution scale). To understand the nature of the synsedimentary faulting, a high-resolution stratigraphic framework was developed from six vertical sedimentary sections measured along the 600m high cliff face, and from detailed correlations along photomosaic panels. Ten lithofacies have been identified and grouped into three different architectural elements that have been used as reference units for the high-resolution kinematic analysis. Syndepositional deformation of these architectural elements indicates that the faults had a polycyclic kinematic behaviour. In the hanging wall, abrupt pinchout of sandstone bodies and unusual local variations in sandstone texture also support the influence of faulting during deposition.