THE TECTONO-MAGMATIC EVOLUTION OF THE OCCIDENTAL TERRANE AND THE PARAÍBA DO SUL KLIPPE WITHIN THE NEOPROTEROZOIC RIBEIRA OROGENIC BELT, SOUTHEASTERN BRAZIL

CLAUDIA SAYÃO VALLADARES, BEATRIZ PASCHOAL DUARTE, MONICA HEILBRON, DIANA RAGATKY

Resumo


The Occidental Terrane is envisaged as the eastern/southeastern reworked margin of the São Francisco/Rio de La Plata plate associated with an E-trending subduction under the Congo plate. The Paraíba do Sul Klippe is part of the Oriental Terrane, envisaged as a portion of the Congo plate. A collisional-stage resulted in intense westward deformation of the Occidental Terrane under intermediate pressure metamorphism (syn-D1+D2 events). A late-collisional stage resulted in subvertical folding and steep shear zones (D3 event). Both stages were associated with voluminous crustal-derived granites. U-Pb and Sm-Nd geochronology as well as geochemical and structural data point to three magmatic episodes: 1) a syn-collisional stage 1; 2) a syn-collisional stage 2; and 3) a late-collisional stage. This paper presents a magmatic evolutionary model for this crustal segment of the Ribeira orogenic belt based on new geological data of Brasiliano granites and data available in the literature.

Palavras-chave


Ribeira belt; Brazilian granitoids; Geochemistry; Sm-Nd isotopic data.

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