The late Pan-African intracontinental linear fold belt of the Eastern Hoggar (Central Sahara,Algeria): geology,structural development,U/Pb geochronology,tectonic implications for the Hoggar shield

The structural development of the Tiririne Belt, located in the eastern Hoggar, central Sahara, Algeria has been entirely controlled by a high-strain, now vertical, N—S-trending zone, along which metamorphism and deformation gradually appear to the north in the Tiririne Formation, a clastic unit up to 8000 m thick whose sedimentological environment is described. U/Pb geochronology on zircons from a pretectonic sill within the Tiririne Formation indicates a pre-660 Ma depositional age. This intracontinental belt has been formed during the ‘late Pan-African’, as shown by the 604 and 585 Ma U/Pb zircon ages obtained on syn- to late-kinematic granitic phases from a circular pluton emplaced in the belt (using λ₈ = 0.155125 · 10^?9 y^?1 and λ₅ = 0.98485 · 10^?9 y^?1). The tectonic implications are discussed in the light of the structural and geochronological data. They suggest an eastwards younging of the peak of Pan-African deformation towards the East-Saharan craton, which has been stable for more than 660 Ma.