## 5 Discussion
### Interregional Correlations  
The surveyed sections in the Errachidia-Boudnib-Erfoud Basin described above have been correlated with other sections surveyed in the Ouarzazate and Agadir basins [17,39,57] along a transverse of about 600 km. Correlations based on lithost stratigraphic landmarks of the Albian-Turonian deposits show a general transgressive character in both parts of the transverse, the eastern part (Ouarzazate and Errachidia-Boudnib-Erfoud basins), and the western part (Agadir Basin). The diagram (Figure 15) shows the main facies types (marine vs. continental). In these three basins, transgressive sediments are represented by lagoonal and shallow marine deposits, while intervals of eustatic regression are marked by the progradation of fluvial deposits. During the Albian-Cenomanian period, the Ifezouane Formation with a mainly fluvial character was deposited over different basements units in the eastern basins. Its equivalent in the western part is the Kechoua Formation, which consists essentially of calcareous facies and some marny intercalations in the distal part of the Agadir Basin (Taghazoute, Tahanaoute, and Askoutti) and red continental silts in the proximal part of the basin (Afansou and Tizi N'Test). During the Cenomanian, the sedimentation continues with the deposits of the Aoufous Formation (red clays, green marks, sandstones, and primary gypsums). This formation is well-developed in the Errachidia-Boudnib-Erfoud Basin and marks the first marine invasion represented by coastal lagoon deposits within the red facies of the alluvial plain. Coeval to the Aoufous Formation, in the Agadir Basin, the Ait Lamine Formation shows purely marine facies represented by green marks, calcarenites, and oyster beds in the distal part of the basin but mainly continental sediments in the proximal part (red siltstones intercalated sometimes with green marks and sandy limestone beds). During the late Cenomanian, estuarine-related sediments were deposited in the Agadir Basin; these are marls, oyster limestones, and calcarenites. In the eastern basins, the deposits become purely marine and are represented by dolomitic limestones, marly limestones, and lumachellic or bioclastic limestones. During the Turonian, black shales and laminated mudstones developed in the Agadir Basin. In the eastern basins, the facies are composed of dolomitic beds, bedded fine limestones containing chert, and bioclastic limestones. The upper Cenomanian and Turonian deposits correspond to the Casbah d'Agadir Formation in the Agadir Basin and the Akrabou Formation in the eastern basins. Correlations show that the Cretaceous series is very reduced in Bou Tazoult and Anounizme. In the latter locality, it is represented only by the Ifezouane Formation. The variegated deposits of the Aoufous Formation and those of the Akrabou Formation are absent. Moreover, the Akrabou Formation's thickness decreases westwards, from the eastern sections where it reaches about 200 m (Tazzouguerte). This decrease in thickness is accentuated in Imiter and Tazoughmite localities where it is reduced to a single bed of 0.5 m. Similarly, the thickness of the Cenomanian-Turonian carbonate unit decreases from the Agadir Basin sections to the east. The thinning of these Cenomanian-Turonian deposits on both sides of Anounizme and their disappearance in this locality suggest the existence of a paleorelief between the two domains. The western basins likely were expressed by a slope towards the west to the Atlantic Ocean, while eastern basins deepened towards the east towards the Tethyan realm via the Sahara (Bechar region). According to [7], the transition between these two domains is likely located in the area between Tinejdad and Goulmima. A comparison of the two parts of the transect highlights marine flooding, which begins well before the \(\delta^{13}\)C anomaly recorded at the Cenomanian-Turonian transition in the Agadir Basin [39]. On the eastern part of the transverse, the \"Infra-Cenomanian\" fluvial series is transgressed by shallow carbonates.