NOVAS EVIDÊNCIAS DE REMANESCENTES OCEÂNICOS NA FAIXA ARAÇUAÍ: AS ROCHAS META-ULTRAMÁFICAS DE SÃO JOSÉ DA SAFIRA

Résumé

Neoproterozoic oceanic slivers have been characterized in the Araçuaí Belt, eastern Brazil. Close to the SãoJosé da Safira town, Minas Gerais State, meta-ultramafic rocks consist of serpentinite with preservedperidotite cores, talc-anthophyllite schists, a diopside-rich rock, and tremolite schist. They are closelyassociated with banded iron formation (magnetic oxide, sulfide and silicate types), muscovite schist andgraphite schist. This rock assemblage is interpreted as an ophiolitic mélange emplaced by thrusts betweentwo different units. One of them, correlated to the Salinas Formation, consists of quartz-mica schist (withgarnet, staurolite, kyanite, and/or sillimanite), sedimentary-derived calc-silicate rock, and sparseorthoamphibolite. The unit correlated to the Capelinha Formation consists of orthoquartzite, hematite andmica quartzites. All described rocks were transported from NE to SW in response to a dextral, obliquethrustsystem. Geochemical data from metaultramafic rocks of São José da Safira indicate an ophioliticorigin. The comparison with data from other Neoproterozoic oceanic remnants (Abadiânia and Fuchuan)corroborates this interpretation.