## 5 Discussion
### Stratagraphic Correlations within the Errachidia-Boudnib-Erfoud Basin  
The studied sections in the Errachidia-Boudnib-Erfoud Basin have been correlated over more than 200 km along the Anounizme-Tazzouguerte transverse (Figure 14). These overall correlations carried out over the interval covering the Cenomanian-Turonian marine limestones (Akrabou Formation) and the underlying siliciclastic deposits, i.e., the Iferzouane and Aoufous formations, make it possible to follow the lateral variations of different facies. The absence of precise bioststratigraphic markers within the red series called \"Infra-Cenomanian\" requires the use of lithost stratigraphic markers. Indeed, the laterally continuous Cenomanian-Turonian unit constitutes a cartographic landmark on the entire Preafrican Trough. The base of the bedded white limestone containing chert is considered, here, as the boundary between the Cenomanian and the Turonian, as already suggested by [9; 13; 14]. This boundary serves as a datum level for all sections. The red series of the \"Infra-Cenomanian\" (Iferzouane and Aoufous formations) can easily be identified in the field as  
Figure 14: Diagram showing the lithost stratigraphic correlation of the studied sections along a west-east transect in the Errachidia–Boudnib–Erfoud Basin. they are overlain by the Cenomanian-Turonian limestone. Red series rest, depending on the places, in concordance with Jurassic formations or even in discordance on the Pan-African or Hercynian basement. This series can be subdivided into two resistant units: a first one consisting mostly of sandstone (Ifezouane Formation); a second mixed unit with intercalations of clays, red sandstones, green marls, and gypsum (Aoufous Formation). In the two sections of Anounizme and Tazoughmite (west of the transverse), the Ifezouane Formation is about 33.5 m-thick and is represented by essentially reddish sandstone deposits showing oblique laminations with some conglomeratic channels unconformably deposited on a Neoproterozoic basement. At the Foum El Kouss section, this formation of about 37 m is formed by metric to multi-metric beds of red sandstone separated by silty sandstone intervals. It lies in angular discordance on Paleozoic schists. At the Tinghir location, this formation thickens to reach more than 140 m. The Ifezouane Formation, here, is well-developed and is represented by a red sandstone series with clayey-silstone intercalations, which are unconformably deposited over a basement of upper Visean age [44]. The formation decreases in thickness again towards the Taddart N'Oumira location (66 m), where it is composed of sandstone facies and some red clayey levels. It lies discordantly on the Paleozoic strata. In the Goulmima and Tadihouse sections, the Ifezouane Formation consists of fine to medium-grained sandstones with some red clayey or silty intervals, but its thickness (31 m and 63.5 m successively) is greatly reduced compared to Taddart N'Oumira. In the Errachidia section, this formation consists of sandstones and is organized into three thick units. Towards the east in Tazzouguerte, this formation is poorly visible, but the increase in its thickness is remarkable. The Aoufous Formation lies in concordance with the Ifezouane Formation and also shows lateral variations in thickness. Indeed, in the west, at the Anounizme section, it is absent, while from Tazoughmite onwards; it is represented by a red clayey interval with rare sandstone levels. Eastwards, a sharp increase in thickness is observed at Imiter (34.5 m) and then Foum El Kouss (143 m) to Tinghir (197 m). In Imiter, this formation consists of reddish sandstones and silty-clayey deposits with small green marly layers. In the Foum El Kouss and Tinghir sections, in addition to the sandstones, red silty and clayey deposits, other facies appear. These are small sandy limestone beds with occasionally biotinylated surfaces, green marl levels, and primary gypsum beds.