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Titre: | Granulitic metamorphism in the Laouni terrane (Central Hoggar, Tuareg Shield, Algeria) |
Auteur(s): | Bendaoud, A. Derridj, A. Ouzegane, K. Kienast, J.-R. |
Mots-clés: | Eburnean Pan-African Granulite Hoggar Laouni LATEA |
Date de publication: | 2004 |
Editeur: | Journal of African Earth Sciences |
Collection/Numéro: | Volume 39, Issue 3-5, June 2004;PP. 187-192 |
Résumé: | 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-H2O 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 °C to 6 kbar at 700 °C; Tidjenouine: 7.5 kbar at 875 °C; to 3.5 kbar at 700 °C; Tin Begane: 13.5 kbar at 850 °C; to 5 kbar at 720 °C), followed by amphibolitization that corresponds to a fall of temperature (from 700 to 600 °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. © 2004 Elsevier Ltd. All rights reserved |
URI/URL: | http://dlibrary.univ-boumerdes.dz:8080/handle/123456789/2223 |
ISSN: | 08995362 |
Collection(s) : | Publications Internationales
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