The clear domains nearly free of inclusions contain up to 0.2 wt.% of TiO 2. (A) Banding reflecting variable abundances of rutile exsolutions. Selected microphotographs of garnet megacryst ED128 and its inclusions. The Ar-Ar and U-Pb ages (in progress) will help decipher the evolution of these different components and will allow to replace the NE algerian massifs in the evolution of the western Mediterranean. These values suggest participation of an enriched component similar to detrital sediments, which is also supported by Pb isotopes. A second group yields significantly lower Nd and Hf isotopic values (down to 0.512200 and 0.28207, respectively) combined with higher Sr isotopic ratios (up to 0.7147). A first group shows a typical DMM signature for Nd and Hf isotopes with Sr isotopic ratios more or less modified by seawater. The Nd and Hf isotopes for both amphibolites and peridotites can be separated into two distinct batches. Peridotites present flat CHUR-normalized REE profiles with a marked negative Eu anomaly for KL samples. Garnets from amphibolites range from almandine to grossular.Īmphibolites display MORB-type REE patterns evolving from slightly depleted to enriched patterns (0.5 This study is focused on the petrology, geochemistry and geochronology of the mantle rocks from Kef Lakhal (KL) and Sidi Mohamed (SM) areas in order to constrain their origin and age. Preliminary works from this area have proposed that both amphibolites from Kef Lakhal and metagabbros from Bou Maiza correspond to components formed in a back-arc basin environment. In the eastern part of North Algeria, basic and ultrabasic rocks outcrop in the Edough massif, which belong to the internal zone of the Magrebides. The dismembered fragments of the Alpine belt recovered in various places around the Mediteranean basin are witnesses of the collisional events between Africa and Eurasia and of the opening of the western Mediterranean basins.
0 kommentar(er)
