Timing of terrane accretion in the Neoproterozoic-Eopaleozoic Ribeira orogen (se Brazil)

New ID-TIMS U-Pb geochronological data of the Oriental terrane combined with detailed geological data of other terranes support the presented tectonic evolutionary model for the central segment of the Neoproterozoic Ribeira belt, southeastern Brazil, that can be subdivided in four major tectonic units: (a) the Occidental terrane, regarded as the reworked margin of the Sao Francisco Craton, to the northwest; (b) the Paraiba do Sul klippe; (c) the Oriental terrane comprising arc complexes, and (d) the Cabo Frio terrane to the southeast. The Oriental terrane and the Cabo Frio terrane were progressively accreted to the reworked continental margin of the Sao Francisco paleoplate. The Occidental terrane contains pre-1.8 Ga basement slivers interlayered with Neoproterozoic passive margin successions (Andrelandia group). The Oriental terrane, focus of the work, was firstly accreted to the Sao Francisco margin at ca. 580 Ma. It displays three structural domains thrusted to NW toward the reworked Sao Francisco margin, from west to east: (a) the Cambuci domain that is interpreted as the fore arc association, (b) the Costeiro domain that contains a distal passive margin succession intruded by the ca. 790 and 635-620 Ma Rio Negro arc complexes, and (c) the Italva domain that comprises marbles, psamitic gneisses and amphibolites of ca. 840, and is regarded both as the proximal passive margin of the Oriental terrane, or a back-arc basin. Syn-to-late-collisional granitoids and three metamorphic episodes ca. 605, 580 and 550Ma indicate a complex history for the collision I. They were also described for the Kaoko, Damara and West Congo (only the youngest one) Pan-African belts located at Occidental Africa, and are supposed to record the main episode of convergence in Western Gondwana. A second collisional stage at ca. 530 Ma accreted the Cabo Frio terrane to the Oriental terrane, and is possibly related with the closure of a back-arc basin located between the Oriental terrane and Kalahari craton, that remained open until the Ordovician. The effects of the collision II were also detected at the Oriental terrane. Finally, late to post tectonic granites marked the tectonic collapse of the orogenic building between 513-480 Ma. (C) 2003 Elsevier Science B.V. All rights reserved.