A new metamorphic constraint for the Eburnean orogeny from Paleoproterozoic formations of the Man shield (Aribinda and Tampelga countries, Burkina Faso)

Progressive metamorphic zones developed in pelites around the Aribinda granite, Burkina Faso, indicate contact metamorphism at 5–6 kbar. Biotite, chloritoid, staurolite–kyanite zones are distributed concentrically around the Aribinda pluton on its northern margin but are displaced by later thrust faults in the south of the Aribinda area and in the nearly Tampelga area. These metamorphic and structural characteristics provide new constraints for the geodynamical evolution of the Eburnean orogeny in the North part of the Baoulé-Mossi domain. They show the leading part of the granitoid emplacement in the thermic structuration of the greenstone belts and the post-metamorphic character of the tangential tectonic. In Burkina Faso, the Eburnean orogeny underwent: (1) initial greenschist-facies metamorphism; (2) emplacement of granitoids at mid- deep-crustal levels leading to unusual medium pressure metamorphism; (3) later thrusting.