This study concerns the south-central part of the Iullemmeden intracratonic basin. The main objectives of the study were sedimentological analysis of the various facies and preliminary description of the nodules bearing phosphate mineralization in the Agougaran sector (Kao area, northern Ader Doutchi). The phosphate-bearing rocks are phospharudites. These occur as nodules of variable size and morphology. The phosphate nodules are hidden in the marl limestones or in attapulgite schists of the Barmou Member. Attapulgite schists contain the highest concentrations of nodules bearing phosphate mineralization. In the mineralized levels, nodules are either scattered or organized in layers or beds. The faunal association of the Barmou Member, which encases in the mineralized nodules, is made up of nautiluses, bivalves, sea urchins, gastropods, foraminifera and ostracods. This faunal association testifies to the emplacement of phosphate mineralization-bearing deposits in a confined marine environment.

This study is concerned with the 2D modelling of the mineralised units of the uranium deposit at the Nord-Taza Satellite prospect (Arlit, Northern Niger). The Nord-Taza Satellite prospect, operated by Aïr Mines Company (SOMAÏR), is an integral part of the uranium deposits in the Arlit sector, which are hosted by sandstones of Carboniferous age and deposited in a fluvio-deltaic environment. The methodological approach adopted consists of correlating the data obtained from development drilling and facing surveys using modelling software such as Surpac and Sermine. The minerals present include orthoclase, quartz, biotite, zircon, monazite and apatite. The lithological analysis showed that the study area is characterised by coarse sandstones with microconglomeratic tendencies, argillites and finely consolidated sandstones. These facies, referred to respectively as Unit 1 (U1), Unit 2 (U2) and Unit 3 (U3) of the Tarât, are the host formations for the uranium mineralisation in the study area. Correlation of data from boreholes and face surveys has shown that high uranium grades are found in the reduced sandstones of units U1 and U3, while low grades are found in the mudstones of unit U2. Information obtained from the Surpac software showed that uranium mineralisation is oriented in a north-south direction and is more concentrated on the western flank of the study area near the Arlit normal fault-flexure. The 2D model produced using the Sermine software showed that U1 has stratiform mineralisation, U2 has discontinuous or isolated lens mineralisation and U3 has chenalising lens mineralisation. The U4 or Madaouéla unit is not mineralised in the Nord-Taza Satellite prospect.

The Ayorou and Kandadji sectors are located in northern Niger’s Liptako in the Téra-Ayorou pluton, composed mainly of granodiorites and various granites. This study investigates the structural characteristics of the granitoids of the Téra-Ayorou pluton in the Ayorou and Kandadji areas. Field and laboratory work revealed two major deformation phases, D1 and D2. Tectonic structures observed on granodiorites and synkinematic biotite granite (foliation, mineral lineation, shear corridors, folds and boudins identified) were assigned to deformation phase D1, which is ductile to semi-ductile. Other structures (quartzo-feldspathic, pegmatitic and doleritic fractures and veins) affecting all lithologies, have been linked to deformation phase D2, which is frankly brittle. The average direction of shortening of the compressive stress responsible for setting up the foliation (S) is generally N-S (Z N185° in Ayorou) and NNE-SSW (Z N225° in Kandadji). The shear zones were controlled by a shortening of average direction Z N195° (dextral shear zones) and Z N135° (senestial shear zones).