The Grès d'Annot Formation is located in parts of Alpes de Haute Provence and Alpes Maritimes in SE France at a tripple junction system of the Alps, the Pyrenees and the Apennines (map). If the tops of the successions are not eroded, their thickness may exceed 1000m. The outcrops comprise an interbedding of siliciclastic beds ranging from shales to conglomerates. During the period between the turn of Eocene and Oligocene (approx. 10Ma), the sediments deposited and onlapped its substrata in a topographic irregular deep-marine basin (pic) with a deposition rate of at least 100m/1Ma (figure).
Three facies associations are applied for separating the turbidites in the succession: GdAI, thinly bedded sandstones with siltstones and shales (pic), GdAII, sequences of medium bedded sandstones (0.3 -2m) separated by thin siltstones and shaless (pic), occasionally with conglomerates and GdAIII, from few meters up to 100m thick sandstone units, often separated by conglomerates and rarely by heterolithics (pic). Furthermore, the Grès d'Annot succession is dividable into two parts: a lower (GdAI and GdAII dominated)- and a upper (GdAII and GdAIII dominated) super-cycle (pic). The sediments of the lower part were transported by gravity flow-types of low, moderate and high density turbidity currents and fluidised flows. The abrupt takeover of the upper part is marked by an erosive boundary with regional sediment-distributary channels (pic). The sediment transport of the upper part is predominantly controlled by an intensified flow regime of fluidised flows mixed with high density turbidity currents and grain flows. Laterally, when focussing basin-wide, a more intensive flow regime controlled the southern part of the basin, since their remnant outcrops constitute coarser-grained sediments compared to the more basin-distal northern part.
Even when the northern deposited sediments have undergone a severer burial (>2800m) and are more compacted than the sediments in the southern locations (burial approx. <1100m) (map), the composition of the sediments across the entire basin is nearly uniform and the rocks are classified as 1st cycle psammite arkoses (fig). Most likely, the basin was supplied by a single source area, whereby the paleoflow was continuously trending north - northwest (map). Conclusively, the source area is determined as the ancient assemblage of the micro-plates of Corsica, Sardinia, Esteral and Maures (fig). However, the northern outcrops indicate an additional minor sediment-supplying source area, based on the occurring conglomerates that the southern outcrops are nearly devoid of.
In sedimentary sequences where the ambiguity and uncertainty of stratigraphic control associated with more traditional methods of correlation such as lithostratigraphy, biostratigraphy and geophysical logging is severe, it is particularly recommendable to apply geochemical correlation techniques in such barren sedimentary sequences, where this method may provide a substantial contribution to advance the correlation between wells, reconstruct paleoflow trends and to identify source areas. Distinct beds demonstrate geochemical fingerprinting, since immobile element ratios of samples of an individual bed are plotting along a regression line in bivariate diagrams. Especially, these fingerprints are convincing when plotting the ratios of xx/xx-xx/xx- and xx/xx-xx/xx. The vertical approach did also show geochemical signatures. However, their resolution was limited to categorise only three geochemical fingerprint suites in an total vertical interval of 350m (diagram). This is caused by the homogeneity of the provenance. No signs of varying grain sizes that may affect the geochemical evaluation and interpretation could be observed between the sampled arkoses that range from 130 - 550µm (diagram).