The Niamey sandstones belong to a group of Neoproterozoic (Infracambrian) deposits of the Nigerian Liptako, sporadically outcropping along the eastern edge of the West African Craton and following the Niger River valley. They rest in major unconformity on the Paleoproterozoic (Birimian) basement of the Niger Liptako. Previous work on these deposits has been fragmentary, particularly as regards their structure, and the investigations carried out aim to make up for these shortcomings. The aim of this study is to determine the deformations that have affected the Niamey sandstones. To achieve these objectives, an integrative approach based essentially on analyses and measurements of deformation structures in the field and their projections in the Win-Tenseur program, in order to calculate stress tensors (σ1, σ2, σ3), was implemented. Structural analysis has identified an extensive pre-Pan-African D1 phase, trending NNW-SSE to NNE-SSW, concomitant with the opening of the Neoproterozoic Ocean, and two Pan-African compressive episodes, NNW-SSE to NW-SE trending D2a and ENE-WSW trending D2b.

The Niamey area lies on the south-western edge of the Iullemmeden Basin. The Continental terminal 3 (Ct3) formation, the subject of this study, represents the last infilling deposits of this basin. In order to determine the depositional environments of the Ct3 formation in the Niamey area, a methodological approach based on field data analysis followed by laboratory analyses was implemented. The main objective of this study is therefore to improve the knowledge of the sedimentary dynamics of Ct3 deposits in the Niamey area. Specifically, the aim of this study is to determine the Ct3 depositional environments. Sedimentological analysis enabled us to distinguish five (5) facies labelled F1, F2, F3, F4 and F5. These facies consist of alternating clayey sandstones and ferruginous lateritic oolitic sandstones with indurated levels, locally showing sandstones levels with unclear oblique bedding. The presence of casts of Gastropods, Lamellibranchs and Echinoderms indicates that the Ct3 deposits were emplaced in a shallow, lagoonal to lacustrine freshwater basin subject to fluvial inputs.

The present study focuses in situ and laboratory determination of geotechnical parameters of soil samples from the Niamey region (Niger). The collected soil samples were analyzed at the geotechnical laboratory (GEO-LAB CONSULT). Petrographic analysis of samples from manual wells showed three stratas of varying thickness. From top to bottom, these are: medium to coarse yellowish-red sand (50 to 80 centimeters), lateritic gravel (20 to 40 centimeters) and ferruginous armour (40 to 60 centimeters). The obtained results from the penetrometer boreholes were used to determine the depth of the foundations, the thickness of the studied stratas and the ultimate stress of the soil for foundations dimensioning. At the Aeroport site, the depth of the lowest point is 1.5 meter, with an ultimate stress of 5.05 bars. The Satu site has a lowest depth point of one meter, with an ultimate stress of 7.47 bar. The Kalley Plateau site gave a lowest depth point of 1.5 meters with an ultimate stress of 2.20 bars, and the Saguia Béné site had a lowest depth point of 1.5 meter with an ultimate stress of 2.15 bars. Analysis of the water content of studied soils, combined with the penetrometric results, shows that water content influences soil strength.

Multi-channel seismic and well data from Agadem (Termit Basin), a Mesozoic–Cenozoic intra‐continental rift basin located in the West and Central African Rift System (WCARS), has been analyzed. Regional unconformities, including the top of acoustic basement, have been identified from seismic data. The correlation of wells in the Agadem Block, as well as the seismic data interpretation, show that the lateral thickness variations of the layers is linked to the synsedimentary normal activation of the N140° to N150° trending fault system of the Termit Basin. The well logs correlation exhibits a high hydrocarbon potential, in the axial zone of the Agadem Block, which is characterized by a strong subsidence rate. This study shows that the NW-SE-trending graben shaped Termit Basin exhibits a tilted block structuring, controlled by the synsedimentary reactivation of normal faults. Two major periods of structuring characterize the evolution of the Termit Basin: - The first period, which was an extension stage, including the first rifting stage relayed by a thermal subsidence, occurred from early Cretaceous to Upper Cretaceous, during the south Atlantic opening. - During the second period, which prevailed from Paleocene to Oligocene, the Termit basin was also affected by a second rifting event, followed by a thermal tectonic subsidence. The NW-SE trending faults was secondly reactivated during a NE-SW extensional regime.

In West Africa, particularly in the Taoudenni, Volta and Beli basins (southeastern border of the Gourma Basin), Neoproterozoic glaciogenic deposits have been assimilated to the Late Cryogenian «Tillites-Carbonates-Silexites» triad. Like those of the Taoudenni, Volta and Beli basins (southeast of the Gourma Basin), the Neoproterozoic formations of the Firgoun region on the southeastern border of the West African Craton exhibit characteristics of the Neoproterozoic triad. This study aims through sedimentological analysis and lithostratigraphic correlations to place the sedimentary sequences of the Firgoun area in their regional context. The Firgoun deposits, resting in fundamental unconformity on the birimian basement of the Niger Liptako, are essentially composed of quartzite sandstones, conglomerates, shales, silexites and more or less metamorphosed dolomitic limestones. The stratigraphic analysis reveals that the Firgoun deposits include 9 lithofacies from the bottom to the top: the lower lithofacies noted Fr1 to Fr3 have been attached to the base formation called «Firgoun Sandstone», and the lithofacies Fr4 to Fr9 related to the «Beli-Garous» formation. The summit lithofacies (Fr6 to Fr8) of this «Beli-Garous» formation, corresponding to a succession of interbedded diamictites associated with carbonate and silexites deposits, have been assimilated to the Neoproterozoic triad.

The present study concerns the south-centre of the Nigerien part of the Iullemmeden intracratonic Basin. A multidisciplinary approach involving sedimentological analysis of facies and determination of fossils has been implemented for the characterization and determination of the Maastrichtian to Paleogene paleoenvironments in the Garadaoua and Garadoumé areas. The stratigraphic series of the study area includes, from the bottom to top, the Formations of: Farin Doutchi, In Wagar, Garadaoua and Ader Doutchi (Ct1 or Ar). The Maastrichtian Formations of Farin Doutchi and In Wagar, as well as the Paleocene Formation of Garadaoua are fossiliferous. Indeed, the base of the Farin Doutchi Formation contains bivalves, foraminifera and sea urchins, while, In Wagar contains remains of vertebrates and casts of gastropods. In the Garadaoua Formation, presence of the benthic foraminifer Ranikothalia bermudezi species made it possible to assign to it an Upper Paleocene age. Moreover, the presence in the Garadaoua Formation of the sea urchin Linthia sudanensis species implies, during this periode, the pre-existence of an epicontinental sea in the Iullemmeden basin. Besides, in the Ader Doutchi Formation, the demonstration of α and γ oolites, as well as proto-oolites, testifies an agitated environment with at least two oolithization phases.

The Pan-African province of South Maradi represents the northern part of Benin-Nigerian Shield, corresponding to the Pan-African mobile zone located in the East of West African Craton. In this basement zone, the distribution of metamorphic formations is marked by gradual transitions: from schists to gneiss and then to migmatites. The schists outcrop in a NE-SW bands, alternating parallely with gneiss bands, limited by the shear zones. The alternation of schists and gneiss bands, associated to ductile shear zones and the existence of a gradual transition from schists to migmatite, raises questions about the geodynamic context of crustal evolution. The study of metamorphic paragenesis (aim of this study), allows to specify the geodynamic context that prevailed in this portion of the pan-African mobile zone of South Maradi. The methodological approach combines petrostructural analysis and determination of mineral assemblages by using the petrographic microscope. The chronology of the metamorphic mineral assemblages and their relationship with the deformation structures made it possible to highlight a prograde phase of metamorphic evolution (green schist facies- amphibolite facies, granulite facies) then retrograde, synchronous with a tangential tectonic and then transcurrent one. Further south in the contiguous Pan-African province of Nigeria, pressure elevation from 6.8 kbars to 9-10 kbars associated with a prograde metamorphism have been related to burial then to a crustal thickening by pile-ups.