Petrography, Mineralogy and Thermodynamic Modeling of Eclogites from the Serkout Area, Central Hoggar, Algeria
The Aleksod terrane Eclogites, sited in the Central Hoggar, preserve a selection of eclogite-facies assemblage (coarse garnet, omphacite, quartz, clinozoisite and amphibole). During retrogression, these minerals were partially substituted with coronas and symplectites of diopside-plagioclase and amphibole-plagioclase. The almandine-dominated garnet proves to enclose heterogeneous compositions (XAlm0.30–0.56). The omphacite displays a high XJd of 0.31. The eclogite-facies coarse amphibole is magnesio-hornblende with NaM4 = 0.31–0.47. The plagioclase is usually secondary exhibiting a range of composition from oligoclase to anorthite (XAn = 0.20–0.99), where albite-rich and anorthite-rich compositions prove to correspond, respectively, to symplectite after omphacite and coronas around epidote. The relevant P-T pseudosections using THERMOCALC-340 are calculated to estimate peak conditions and trace the P-T evolution. At H2O-saturated conditions, inclusions of amphibole in garnet core with garnet composition from core to inner rim are used to trace pre-peak P-T path from 14 kbar–610 °C to 18 kbar–700 °C. At H2O-undersaturated conditions, the retrograde path has been traced using secondary phases as plagioclase, diopside and amphibole at 10 kbar–720 °C.
KeywordsEclogite Serkout Hoggar Thermodynamic modeling P-T path
- 2.Doukkari, S., Ouzegane, K., Godard, G., Diener, J.F.A., Kienast, J.R., Liégeois, J.P., Arab, A., Drareni, A.: Prograde and retrograde evolution of eclogite from Adrar Izzilatène (Egéré-Aleksod terrane, Hoggar, Algeria) determined from chemical zoning and pseudosections, with geodynamic implications. Lithos 226, 217–232 (2015)CrossRefGoogle Scholar
- 3.Bertrand, J.M.L.: Evolution polycylique des gneiss précambriens de l’Aleksod (Hoggar central, Sahara Algérien). Thèse d‘Etat, In: C.N.R.S. (C.R.Z.A) (ed.), aspects structuraux, pétrologiques, géochimiques et géochronologiques. Série Géologique 19, p. 350 (1974)Google Scholar