This study focuses on highlighting and controlling of uranium mineralization in the Ingall area (Northern Niger). The study sector is an integral part of the Tim Mersoï basin located to the northern part of the Iullemenden syneclise. Located on the western edge of the Aïr Massif, this basin, known for its uranium mineralizations, has a sedimentary filling ranging from Devonian to Lower Cretaceous. All the sedimentary formations of this basin end in a bevel on the western edge of the Aïr Massif. To carry out this study, the radiometric airborne geophysics technique was first deployed to highlight surface uranium anomalies. These were then verified by ground radiometry technique. The mapping work then identified the major geological structures that controlled the emplacement and distribution of the mineralization. Drilling and logging techniques were used to determine the mineralization host formations, the Assaouas and Tchirezrine-2. The results of this work show two envelopes of surface uranium anomalies at the 100 cps to 200 cps cut-off in the centre of the study area. These anomalies have a vertical extension to a maximum depth of 240 m, where highest values are located. This uranium mineralization occurs as lenticular ore bodies in the Ingall sector. Tectonic structures (normal faults), palaeogeography and chemical elements (reducing elements) are the main factors controlling the concentration and distribution of this mineralization. This study shows that this area, underestimated for decades, is potentially rich in uranium mineralization.

The N70° DASA graben is a closed-rift that seems to be the deepest part of the Tim Mersoï Basin, which is located in the northwestern part of Niger in West Africa. It contains more than 805 m of Paleozoic-Mesozoic sediments. The tectonic subsidence and uplifting was calculated by using well log data and deducing the variations in sedimentary thicknesses over time. Geological mapping and tectono-sedimentary analysis indicate that the structural evolution of the DASA trough is characterized by two major periods: (1) the first period was marked by an uplift stage ranging from the Carboniferous to the Permian. It was typified by a weak subsidence rate (3.45 m/Ma on average), under a transpressive tectonic regime, with a decrease in the thickness of the sedimentary series along the axial zone of the trough, and an increase of the thickness towards the border areas; (2) the second period was characterized by a higher subsidence rate (4.11 m/Ma on average) related to a change in the tectonic regime. It was marked by a rifting stage preserved over a long period, subjected to an extensive tectonic regime, from the Triassic to the lower Cretaceous, during which the highest thicknesses of the sedimentary series developed in the axial zone of the graben. The structural and sedimentological features defined the DASA graben as a particular type of syn-sedimentary basin evolving from a transpressive tectonic regime during the Paleozoic to an extensive tectonic regime during the Lower Mesozoic. Thus, the second period marked by an extensional regime would probably be related to the opening of the first stages of the Atlantic Ocean.

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The Tim Mersoi Basin is a very rich uranium basin. It is a basin that belongs to the Iullemenden syncline located in the northern part of Niger. Research work in recent years in this basin has revealed significant mineralization. The present study in this basin is based on the QEMSCAN and petrographic analysis of samples particularly highlighted during recent exploration campaigns. This study has shown that the basement of the sector is granitic in nature but the presence of an andesite intrusion has been revealed in this studied area. The presence of this andesite dyke has also shown a close link with uranium mineralization.