Abstract

The Cime Dieu de Delfy outcrop is located in the Sanguinière Massif, at the western border of the Argentera–Mercantour Massif, 70 km (43 mi) northwest of Nice. It belongs to the Grès d’Annot Formation, which outcrops in the Tertiary foreland basin of the French Southern Alps, formed by the Alpine orogeny. The Cime Dieu de Delfy outcrop corresponds to the central part of the Sanguinière subbasin, which was one of the tectonically induced narrow troughs (5–10 km [3–6 mi] wide), controlling turbidite sedimentation during late Eocene–early Oligocene times. The whole Grès d’Annot Formation is 800 m (2620 ft) thick and corresponds to deposits on a sand-rich, confined turbidite ramp, probably fed by the Quatre Cantons fan-delta system, 35 km (22 mi) southeast.

Thanks to the presence of numerous recent gullies, the Cime Dieu de Delfy outcrop provides an excellent three-dimensional (3-D) view of the architecture of this turbidite system. This paper describes in detail the central part of the main cliff, 150 m (492 ft) thick by 1500 m (4920 ft) long, which offers both a strike view (sections 1 to 4) and a dip view (sections 4 to 8) of the architectural elements.

The turbidite ramp deposits are repetitively organized in coarsening-upward, then fining-upward, fourth-order depositional sequences, approximately 50 m (164 ft) thick, characterized by specific facies associations and architectural elements.

The first part of this paper presents the stratigraphic framework and the depositional environment of the turbidite system. We then describe the geometric characteristics and the facies organization of the main architectural elements (muddy debris flows, sheet sandstone bodies, erosional and depositional channels, and thin-bedded heterolithic layers). Finally, using 3-D seismic and dynamic (well-test) modeling of a 3-D geocellular model reconstructed from the outcrop, we analyze the seismic and fluid-flow-dynamic signature of these architectural elements.