Abstract
The Anuri Syenitic Dyke (72 km 2 ) is the south representant of a 1000 km N-S alignment of syenitic dykes which occur at the East Bahia. As the others bodies, Anuri is essentially composed of hypersolvus ultrapotassic syenites, which show the records of its diferentiation by the presence of mafic-ultramafic apatite-rich cumulates. Its crystallization age of 2095 ± 4 Ma (U-Pb zircão ) is quite similar with results obtained for the other syenitic dykes, which suggest that their intrusions occur almost at the same time, sincronically, after the Transamazonic Orogeny climax. The geochemical data reveal that Anuri syenites are Ba, Sr, P, LREE enriched and show negative anomalies of Ti and Nb, suggesting a mantelic source subduction related. The initial Sr ratio and εNd values confirms the presence of this anomalous mantle. These data suggest that at the end of Transamazonic Orogeny, at the São Francisco Craton, there were particular conditions which allow the generation of alkaline magmas through the melting of an EMI reservoir.
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