Stratigraphy, palaeontology and sedimentology of the Upper Cretaceous of northern Tademait (Sahara, Algeria)

Abstract

Thorough sedimentological and palaeontological analyses of four expanded Upper Cretaceous sections in northern Tademait had allowed us to address and reconsider the stratigraphical framework of the so-called ‘Continental Intercalary’ and ‘Hamada series’ in this remote Saharan area. These four sections (i.e., Meguidene, Gara Samani, Oued El Mezaourou-Gour Louazouaza, and El Menia) document Upper Cretaceous strata overlying post-Palaeozoic substrata and ranging from the clastic Gara Samani Formation (of supposed early Cenomanian age), through the El Golea Clays (lower–middle Cenomanian), the Gour Louazouaza Formation (lowermost upper Cenomanian, with the Oued El Mezaourou Limestone Member ranging from the Neolobites vibrayeanus to the Vascoceras gamai ammonite zones of the uppermost Cenomanian, and the Marls of Gara Mta El Mar Member of the Choffaticeras sinaiticum ammonite Zone in the lower, but not lowermost, Turonian), to the Ain El-Hadjaj Formation (of alleged Campanian age). Most efforts have concentrated on the ‘mid’-Cretaceous deposits that yield vertebrates and diversified ammonite and macrofossil assemblages. In spite of these improved correlations, further bio-chronostratigraphical data are needed in order to constrain the stratigraphical gap within the Gour Louazouaza Formation at the Cenomanian–Turonian boundary (C/TB) better. The succession studied can be correlated with other similar-aged sections in North Africa and illustrates the development of braided fluvial and aeolian dune-interdune environments followed by a ramp depositional system in response to the early Late Cretaceous second-order sea level rise along the southern margin of the Tethys.