Analyse Sedimentologique Et Paleo ¬ Geographie Des Sediments Miocenes (langhien-serravalien >des Environs De Tebessa (nord-est De L'algerie)

In the vicinity of Tébessa, the authors' investigations, on the Miocene sediments of the Langhian-Serravalian age, have established the presence of two different sedimentary basins, having different evolutions. The southern basin has a regression profile (offlap and toplap structures) towards the north while the northern basin has a transgression profile (onlap and toplap structures) towards the west.These twodifferent basins were controlled by thedifferent conditions of subsidence. The sequential correlation, the granulometrical analysis, the structures and the sedimentary environments determination are the essential considered methods to determinate two different types of sedimentation,and consequently the two basins with different subsidences. The Miocene sediments of these two isolated basins were accumulated within the erosion surface of previous sediments folded during the fini-Lutetian atlasian phase. The surface of accumulation of southern basin was, only in the beginning, slightly covered by the sea, which moved back afterwards to the east. However, the one of the northern basin was much more subsiding and has generally known a marine sedimentation which passed to a temporary emersion at the end of Langhian-Serravalian. The transgression had came from the east and the basin became deeper towards the west. A continental alteration iron crust seems to be the same age for the two basins in question. Within the northern basin, the age determination of Miocene sediments has proved a Tortonian transgression within the sediments above the crust covering those of Langhian-Serravalian. By analogy, the azoic southern basin is likewise considered as Langhian-Serravalian underneath the iron crust and Tortonian over it.