Miyouna

The paleoenvironmental and paleogeographic study of the Tertiary period in the northern part of the Senegalese basin using the isobath, isopach, and lithofacies methods revealed the following results: Paleogene deposits are dominated by carbonates, while Neogene deposits are detrital. The spatial distribution of lithofacies follows geomorphological units related to the nature of the inputs, distance from the shore, and hydrodynamics of the environment. This sedimentation took place in a coastal to sub-coastal bay-type environment in the Paleocene, an internal to external continental shelf in the Lower Eocene, a shallow coastal environment in the Middle Eocene, and an open marine to lagoonal environment from the Upper Eocene to the Oligo-Miocene. The Tertiary period in the study area was marked by two transgressive phases from the Paleocene to the base of the Middle Eocene and from the top of the Upper Eocene to the Miocene, and two regressive phases at the top of the Middle Eocene and the Miocene. The axis of penetration of marine currents was located to the south, with a secondary route to the northwest. At the end of the Middle Miocene, the basin evolved mainly into a continental regime.