THE SANDY UPPERMOST OLIGOCENE CHANNEL AND THE MIOCENE OF SIDI-AFFIF AREA IN THEIR EAST ALGERIAN STRUCTURAL SETTING - THE SAHARAN ORIGIN OF THE NUMIDIAN AND THE CALENDAR OF THE MIOCENE OVERTHRUSTS

To the E of Constantine, the Sidi Affif area is a syncline formed afte r the stacking of Tellian nappes lying over the Sellaoua relative auto chthonous unit. The lower Tellian unit shows particularly an uppermost Oligocene coarse turbiditic sandy sequence, showing the ''Numidian'' facies. The sense of turbiditic currents indicates therefore that the filling comes from the SE. The Sidi Affif area can represent a new Sah aran filling passage. The uncomfortable Miocene of the Tellian units ( G. trilobus zone) is older than the first unconformable Miocene beds o f the Sellaoua basement or those of the ''post-nappes'' Constantine ba sin (P. sicana zone). Therefore, the Tellian units were stacked before the appearance of Praeorbulina sicana and were transported southwards afterwards, carrying the Constantine-like piggyback basins, during th e Tortonian.