ND ISOTOPE SYSTEMATICS RELATED TO PROTEROZOIC EVOLUTION OF THE CENTRAL RIBEIRA BELT IN THE STATE OF SÃO PAULO, SE BRAZIL

ELTON LUIZ DANTAS, PETER CHRISTIAN HACKSPACHER, ALLEN HUTCHESON FETTER, KEI SATO, MÁRCIO MARTINS PIMENTEL, ANTÔNIO MISSON GODOY

Resumo


New Sm/Nd data from different lithologic units of the Ribeira Belt (RB), southeastern Brazil, provide important information about the crustal architecture and geologic evolution of the region. Nd data of basement gneisses of the RB indicate that they represent Paleoproterozoic crustal growth, whereas those of the supracrustal sequences suggest provenance from both Paleoproterozoic and younger sources. On the basis of their Nd signatures, felsic brasiliano plutons derived largely from Paleoproterozoic basement, but systematic variations in their TDM model ages as a function of their chemistry may reflect differences in fractionation, vertical lithospheric heterogeneity, or possibly some contributions from the asthenospheric mantle.

Palavras-chave


Nd signature; Ribeira Belt and Isotopic Evolution.

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