Lithostratigraphie et palynologie du Dévonien-Gothlandien gré­seux du bassin de Polignac (Sahara)

In the Fort-Polignac Basin, Gothlandian and Lower Devonian deposits are made of a succession of clayey and sandy sediments. On the basis of data from wells in the northern part of this area in particular (Tinrhert), the authors propose a subdivision into four lithostratigraphic formations and a terminology for the sediments between the top of the Graptolites Clay and the base of the Clayed Devonian (Givetiano-Frasnian).
These sediments contain well differentiated associations of spores, acritarchs and chitinozoans. The zones characterized by these associations are used as a chronostratigraphic base for correlations between the wells. These correlations reveal a northward evolution of facies of different levels as well as a continuity of energy levels v within successive sequences and an approximate parallelism between lithofacies and chronological lines.