Caractéristiques structurales des granitoïdes des secteurs d'Ayorou et de Kandadji (Liptako, Ouest Niger)

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).