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.

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.