Geological Society of London
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2. Grès d'Annot Formation, SE France (Tomasso et al.)

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posted on 2020-01-14, 11:03 authored by K.J.W. McCaffrey, D. Hodgetts, J. Howell, D. Hunt, J. Imber, R.R. Jones, M. Tomasso, J. Thurmond, S. Viseur
Salt withdrawal minibasins contain significant petroleum reservoirs in many petroleum provinces around the world, such as the deep northern Gulf of Mexico and offshore Brazil. These minibasins are typically connected by large canyon-like channels that serve as conduits for sediment gravity flows bypassing from proximal basins into adjacent distal basins. The Grand Coyer sub-basin of the Eocene–Oligocene Grès d'Annot Formation of the southwestern French Alps provides an excellent outcrop analogue of an interbasinal conduit that connects the proximal southern Annot sub-basin to the distal northern Trois Evéchês sub-basin. Stratigraphic columns, palaeocurrent, photomosaic and lidar data were collected to address the stratigraphy of the conduit. This virtual fieldtrip visits several of the key exposures around the Grand Coyer sub-basin, illustrating and analysing the stratigraphic packaging moving from lower to upper fill, from axis to margin, and from proximal to distal deposition. Using a detailed, outcrop-based geological model of the conduit, large (field) scale forward seismic models are used to contrast the geometries that we see in the outcrop with those that we would resolve on seismic images. Lessons learned from these exposures could be used to better predict sand distribution and reservoir geometry within interbasinal conduits.