Les ammonites du Cénomanien des massifs de Hameimat (Tébessa, Atlas saharien oriental, Algérie) : systématique et biostratigraphie

Cenomanian ammonites from the Hameimat massifs (Tébessa, eastern Saharan Atlas, Algeria) : systematics and biostratigraphy. - North of Tébessa (eastern Saharan Atlas), the North Hameimat (HN) and South Hameimat (HS) massifs display extensive Cenomanian outcrops rich in marine macrofossil invertebrates. Among the ammonites collected, 15 species are described and identified. Their biostratigraphic analysis allows to propose an original biostratigraphic framework for the Cenomanian of this area. Four biozones are subsequently recognized : the Mantelliceras mantelli (middle Lower Cenomanian), Acanthoceras rhotomagense (middle Middle Cenomanian), Calycoceras naviculare (lower Upper Cenomanian) and Metoicoceras geslinianum (middle Upper Cenomanian) zones. The Mantelliceras mantelli Zone can be divided into two subzones : the Sharpeiceras schlueteri Subzone (at the bottom) and the Mantelliceras saxbii Subzone (at the top). Comparison of these new results with those of adjacent areas (Boukhadra, Morsott and Ouenza) allows completing the local biozonation. It documents close similarities with those of Kalaat Senan (Tunisia) and northwestern Europe. The fairly wide geographical range of these ammonites during the Cenomanian supports faunal homogeneity and belonging to the same paleobiogeographic domain. Finally, these ammonite assemblages allowed to refine correlations between both sides of the Tethys realm.