2.9 to 1.9 Ga paleoalterations ofArchean granitic basement of the Franceville basin (Gabon)

•Basement of Chaillu massif is composed of diorite, tonalite, granodiorites, granite.•Most of these rocks present evidences of a propylitic alteration.•Mineral reactions produced a Mg chlorite, epidote, allanite, titanite paragenesis.•Illite associated with hematite has transformed the previously propylitized rocks.