The southern Grès d’Annot outcrops (French Alps): an attempt at regional correlation

Abstract

During Eocene-Oligocene times, the Gr~s d'Annot turbidite system (French Alps) was deposited in several tectonically controlled sub-basins, which were mainly fed from a southern major sediment source: the Corsica-Sardinia Massif. In order to establish regional correlations in the southern part of the basin, four kilometre-scale outcrop areas were studied in detail. From south to north these are: the St Antonin, Annot, Grand Coyer and Chalufy areas. The results are: (1) an updated chronostratigraphic framework, (2) a major SE-NW correlation panel, approximately 400m thick and 50km long, parallel to palaeocurrent directions, within which all stratigraphic units are defined in terms of sedimentology and micropalaeontology and (3) some correlation panels at outcrop scale (around 5 km long and several hundred metres thick), within which all stratigraphic units are defined as before, but with the addition of a direct visual control on correlations, which enables the reconstruction of higher resolution geometry. Seven time-equivalent stratigraphic packages have been correlated from upstream to downstream, making use of micropalaeontologic constraints, and their geometric and facies evolution have been reconstructed through times. This evolution may be related to different stages in the basin deformation, induced by the east to west development of the Alpine foreland basin.

Sediment Distribution and Architecture Around a Bathymetrically Complex Basin: An Example from the Eastern Champsaur Basin, Se France

“…(3) An upper sand interval termed ''upper sand package,'' which is around 500 m thick, and has a moderate net-to-gross. similar in character to thick heterolithic intervals described in the Grès d'Annot remnants by du Fornel et al (2004). This interval serves as a basin-wide marker and correlation datum; it may even be usable as a regional datum in the absence of biostratigraphic or other means of correlation (du Fornel et al 2004), allowing correlation between turbidite subbasin elements.…”

“…No fossils have been recovered from the marls of the Champsaur Basins, but they are found in southern parts of the Grès d'Annot Turbidite System. Mougin (1978) has described planktonic and benthic foraminifera species found in the Marnes Bleues, and postulated deposition in water depths of up to 900 m, while du Fornel et al (2004) postulate water depths of between 100 and 500 m. The Marnes Bleues are interpreted to be the product of hemipelagic deposition. A pilot biostratigraphic study of the western Grès du Champsaur was undertaken by some of the authors, but a strong metamorphic overprint prevented recovery of dateable material.…”

Lateral termination of the north‐directed Alpine orogeny and onset of westward escape in the Western Alpine arc: Structural and sedimentary evidence from the external zone

“…This suggests that during the Eocene, the Apulian orogenic wedge moved consistent with the African plate over a south‐dipping continental subduction zone, to provide flexural loading of the European lithosphere. The lateral termination and confinement of the Alpine Paleogene flexural basin occurs in Haute Provence, with local westward facies migration [ Sztrákos and Du Fornel , 2003; Du Fornel et al , 2004; Puigdefàbregas et al , 2004]. Even there, northward to northwestward propagation of deformation is recorded during the late Eocene (southern margin of St Antonin basin [ Stanley , 1980; Tempier , 1987]).…”

Two-phase orogenic convergence in the external and internal SW Alps

“…Sediment supply increased during the latest Priabonian and early Rupelian as clastic turbidites (Grès d'Annot) were supplied from the exhuming Sardinia-Corsica block to the south and later by the Maures-Esterels massif (Joseph & Lomas 2004). These turbidites were deposited in SE-NW-oriented synclinal sub-basins (Elliott et al 1985;Du Fornel et al 2004). The area was overthrust by the Embrunais-Ubaye nappes (Kerckhove 1969) toward the end of the Rupelian (around 30 Ma).…”