Sedimentary sequences in the Upper Cretaceous of Aures Mountains (Algerie). Eustasy, tectonics and subsidence: a development

Sedimentary sequences in the Upper Cretaceous of Aures Mountains (Algerie). Eustatsy, tectonics and subsidence: a development. The Upper Cretaceous of Aures has been studied using a sedimentological approach to characterize the sequential organisation and deposits distribution in the basin. The sequential chain which was observed has been correlated to eustatic cycles defined on a global scale. Palaeogeographic reconstruction shows a basin with its south margin corresponding to a proximal platform domain with essentially carbonate deposits and toward the northeast, marly sedimentation of pelagic nature. The influence of NW-SE to WNW-ESE accidents on sedimentation control has been found preponderant. Therefore a system of tilted blocks toward the south characterizes a large part of the basin. The subsidence evolution through Upper Cretaceous is marked by a recovery of a tectonic distension during some phases (Late Albian and Lower Turonian) and an essentially thermic subsidence during the other periods. Finally some precocious tectonic phases appeared as early as the Santonian-Campanian transition. The evolution of the basin was thus controlled by the drift of the African plate during the expansion of the Atlantic ocean and also the tectonic influence which began to appear in north Alpine domain.Original Abstract: L'etude sedimentologique du Cretace superieur caracterise l'organisation sequentielle et la repartition des depots dans le bassin des Aures. Le decoupage sequentiel realise est correle aux cycles eustatiques globaux. Dans le bassin, la marge sud correspond a un domaine de plate-forme proximale a depots essentiellement carbonates. Vers le nord-est, la sedimentation marneuse pelagique se produit en contexte marin profond. L'influence des accidents tectoniques NW-SE a WNW-ESE implique un dispositif en blocs bascules vers le sud-ouest dans une grande partie du bassin. L'evolution de la subsidence est marquee par une distension tectonique a l'Albien terminal (Vraconien) et au Turonien inferieur et une subsidence essentiellement thermique dans les intervalles. Une phase tectonique precoce se manifeste des le passage Santonien-Campanien. L'evolution du bassin au cours du Cretace superieur enregistre la derive de la plaque africaine associee a l'expansion de l'ocean Atlantique. Elle temoigne de l'influence tectonique qui commence a se manifester dans le domaine alpin septentrional en voie de serrage.