Dynamic Controls on Sedimentology and Reservoir Architecture in the Alpine Foreland Basin
A Field Guide to the Eocene-Oligocene Grès d'Annot Turbidite System of SE France
Philippe Joseph1, Yannick Callec2 and Mary Ford3
1 IFP Energies nouvelles, 1-4 avenue de Bois-Préau, 92852 Rueil Malmaison, France, e-mail: email@example.com
2 BRGM, Service CDG/CG, 3 avenue Claude Guillemin, 45060 Orléans Cedex 2, France, e-mail: firstname.lastname@example.org
3 CNRS-ENSG, Rue du Doyen Marcel Roubault, BP40, 54501 Vandoeuvre-lès-Nancy Cedex, France, e-mail: email@example.com
The Grès d'Annot system, deposited during the late Eocene and early Oligocene (Priabonian-Rupelian) in the Tertiary foreland basin of SE France, is an important example of a confined sand-rich turbidite system, offering spectacular exposures over an area of over 5000 km2.
The establishment of the clastic system is related to the development of the alpine foreland basin that started with a regional flexural basin in the Eocene, followed by the creation of synclinal depocentres due to gentle folding of the underlying Mesozoic succession above various décollement levels. A true piggy back basin developed at Barrême in the early Oligocene, where alluvial sedimentation was established sourced from the internal Alps, necessitating the termination of the Grès d'Annot depositional system and uplift of the internal fold and thrust belt.
During the late Eocene and the early Oligocene active thrusts, folds, oblique strike slip and normal faults as well as gravitational normal faults, generated a complex basin floor topography within the sub-basins of the alpine foredeep such as Peira Cava or Annot. In contrast to the original image of a sandy cone sourcing from a submarine canyon incised into the continental slope, the Grès d'Annot system is now thought of as an ensemble of shallow turbiditic ramps directly connected to fan deltas (Quatre Cantons, Saint Antonin), fed from the south by the massifs of Sardinia-Corsica and Maures-Esterels. On these ramps sediment transit was via a system of ephemeral, shallow channels that fed prograding elongated tongues : their activity was probably linked to the frequency of fluvial flood supply (hyperpycnal flows). Within the basin itself these evolved into non-confined turbidity currents that deposited sandy lobes in tabular beds.
The aim of this excursion is to study the organization of facies and stratigraphic architecture of the different elements of the Grès d'Annot depositional system. We will examine:
- the different phases of infill of the confined Annot sub-basin in the south and their relationship to synsedimentary tectonics (in particular the Saint Benoit-Braux Fault system).
- The dispersion of turbidites in planar sandy lobes to infill a basin floor topography in a more distal part of the basin (Chalufy).
- The final phase of piggy-back basin evolution and the closure of the main turbidite basin corresponding to the arrival of the first erosional products from internal zones.
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The way to cite this ebook is the following:
JOSEPH P., CALLEC Y. & FORD M. (2012). Dynamic Controls on Sedimentology and Reservoir Architecture in the Alpine Foreland Basin - A Field Guide to the Eocene - Oligocene Grès d’Annot Turbidite System of SE France. IFP Energies nouvelles e-books. DOI : 10.2516/ifpen/2012001 http://books.ifpenergiesnouvelles.fr.