ملخص: In the Laouni terrane, which belongs to the polycyclic Central Hoggar domain, various areas contain outcrops of formations showing granulite-facies parageneses. This high-temperature metamorphism was accompanied by migmatization and the emplacement of two types of magmatic suite, one of continental affinity (garnet pyroxenites and granulites with orthoferrossilite-fayalite-quartz), and the other of arc affinity (layered metanorites). Paragenetic, thermobarometric and fluid-inclusion studies of the migmatitic metapelites and metabasites make it possible to reconstruct the P-T-aH2O path undergone by these formations. This path is clockwise in the three studied areas, being characterized by a major decompression (Tamanrasset: 10.5 kbar at 825 [deg]C to 6 kbar at 700 [deg]C; Tidjenouine: 7.5 kbar at 875 [deg]C; to 3.5 kbar at 700 [deg]C; Tin Begane: 13.5 kbar at 850 [deg]C; to 5 kbar at 720 [deg]C), followed by amphibolitization that corresponds to a fall of temperature (from 700 to 600 [deg]C) and an increase in water activity (from 0.2-0.4 to almost 1).The main observed features are in favour of petrogenesis and exhumation related to the Eburnean orogeny. However, the lacks of good-quality dating work and a comparison with juvenile Pan-African formations having undergone high-pressure metamorphism, in some cases reaching the eclogite facies, do not rule out the possibility that high-temperature parageneses are locally due to Pan-African events.

لغة: إنجليزية