Abstract
Abstract The Morro do Coco granite (MC) is a post-collisional intrusive body that was emplaced at Ribeira Belt, in the Cambro-Ordovician, succeeding the final stages of the Gondwana supercontinent amalgamation. This unit requires more studies, contrasting with similar best investigated occurrences of the central Ribeira Belt. This work presents a detailed investigation of such unit using petrography, Inductively Coupled Plasma (ICP), X-Ray Fluorescence (XRF) whole-rock geochemistry, U-Pb (SHRIMP) geochronology and Sm-Nd isotopes. The rock is a nearly undeformed syenogranite, geochemically classified as a high-K calc-alkaline magnesian, with metaluminous to slightly peraluminous affinity. Strongly light rare earth elements (LREE)-enriched patterns with significant negative Eu anomalies, typical of post-collisional granites, are identified. Similarly to other post-collisional granites of the central Ribeira Belt, U-Pb zircon data provide crystallization age of 496 ± 3 Ma . Sm-Nd isotopic data suggest crustal magma source as indicated by eNd(496) of -9, 143Nd/144Nd ratios between 0.511747 and 0.511752 and Mesoproterozoic TDM ages of 1.3 Ga. Based on its geochemical characteristics, morphology and geochronology, this unit is considered here as a member of Nova Friburgo Suite. Geochronological data defined three pulses of magmatism in this part of the orogen during the Cambro-Ordovician (515, 490 and 460 Ma).
Highlights
During the Neoproterozoic-Paleozoic, Brasiliano/PanAfrican thermotectonic events took place at the margins of the São Francisco paleocontinent (Brazil) and another plate located to the east, possibly the Congo paleocontinent (Heilbron et al 2000, Brito Neves et al 2014)
Trouw et al 2000), resulted in a series of collisions that culminated in the amalgamation of the Gondwana supercontinent from ca. 580 to 510 Ma
Eight thin sections of Morro do Coco granite (MC) granite were studied under transmitted light petrography at the Universidade Federal do Rio de Janeiro (UFRJ)
Summary
During the Neoproterozoic-Paleozoic, Brasiliano/PanAfrican thermotectonic events took place at the margins of the São Francisco paleocontinent (Brazil) and another plate located to the east, possibly the Congo paleocontinent (Heilbron et al 2000, Brito Neves et al 2014). The convergence between these two continents and possibly a third one, the Paranapanema block which is presently interpreted as hidden under the Paleozoic Paraná basin in Brazil (cf Trouw et al 2000), resulted in a series of collisions that culminated in the amalgamation of the Gondwana supercontinent from ca. The post-collisional magmatism at Ribeira and Araçuaí Belts encompasses mainly high-K calc-alkaline granitoids, minor dioritic and a single manifestation of true shoshonitic rocks (e.g., Martins et al 2016)
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