Structures and deformation phases affecting the Diagorou-Darbani greenstone belt south of Téra (Liptako, West Niger, and West African Craton)

The present study focuses on the geological formations of the Diagorou-Darbani greenstone belt of southern Téra in the Niger Liptako (NE portion of the Man Shield of the West African Craton). The main objective of this study is to characterize the deformation phases that affected the Diagorou-Darbani greenstone belt to the south of Téra. The methodology implemented is based on a structural analysis using field data. These formations are affected by two major deformation phases, D1 and D2. Phase D1 comprises three episodes: D1a, D1b and D1c. The first episode (D1a) developed the S1 cleavage (NE-SW). This episode is linked to a NW-SE shortening (N130°). The second episode (D1b) is marked by S2 crenulation cleavage, micro-folding and the dextral reactivation of N45° shear zones. This episode is linked to an E-W shortening. The third episode (D1c) is highlighted by the NW-SE S3 fracture cleavage and the sinistral reactivation of the N45° shear zones. A N-S to NNE-SSW shortening was obtained for episode D1c. Phase D2 is essentially brittle. It favoured the development of submeridian fractures and conjugate WNW-ESE (sinistral) and ENE-WSW (dextral) shear fractures. This deformation is compatible with a generally E-W direction of shortening.