Comment on “Tectono Metamorphic Evolution of the Central Ribeira Belt, Brazil: A Case of Late Neoproterozoic Intracontinental Orogeny and Flow of Partially Molten Deep Crust During the Assembly of West by Meira et al.

Abstract

The commented article contributes with new metamorphic petrology and U‐Pb geochronology data concerning the sin‐collisional stage of two terranes (Embu and Costeiro) belonging to the southern Ribeira orogen (not Central Ribeira belt, as the title suggests), in order to propose an intracontinental evolution for the Ribeira‐Araçuaí orogenic system. Several issues regarding their review of the literature and interpretation of data should be considered in face of the proposition for an intracontinental evolution of an orogenic system that has long been considered as having developed through a Wilsonian sequence of events, involving continental rifting and ocean development, subduction and building of magmatic arc, terrane accretion, and continental collision in the context of amalgamation of Gondwana. In order to contribute to a comprehensive discussion of the tectonic evolution of the Ribeira‐Araçuaí orogenic system, we bring forward the following points that have not been properly acknowledged by the authors in their proposed tectonic scheme. Without substantial new data set and without integrating all the available age, petrologic and deformational data, there seems not to be commented enough evidence for the proposal of an intracontinental evolution for the Ribeira‐Araçuaí orogenic system. In contrary, an accretionary to collisional model is preferred because it in fact integrates all the documented tectonic features: subduction of passive São Francisco paleocontinental margin, generation of magmatic arcs with typical signatures of modern ones elsewhere in the world, three accretionary‐collisional episodes, and an episode of orogenic collapse in the Cambro‐Ordovician transition, associated to slab breakoff and upwelling of asthenosphere.

Reply to Comment by Heilbron and Valeriano on “Tectono Metamorphic Evolution of the Central Ribeira Belt, Brazil: A Case of Late Neoproterozoic Intracontinental Orogeny and Flow of Partially Molten Deep Crust During the Assembly of West Gondwana”

“…Contrary to the statement by Heilbron and Valeriano (2020), nappe systems and large-scale ductile lower crustal flow have been described in one of the best-characterized ancient intracontinental orogens (Petermann Orogen, Raimondo et al, 2009Raimondo et al, , 2010. Indeed, these authors highlighted that the whole deformational, petrologic, and geochronologic data available for the Petermann Orogen suggest a comparable evolutionary history between this intracontinental orogen and the world's foremost modern collisional orogen, the Himalayan-Tibet Orogen.…”

“…Two subsequent Ediacaran age collisions (between ca. 620 and 565 Ma) have been proposed to explain the geochemical and geochronologic data from the Central and Northern Ribeira belts (summarized in Heilbron et al, 2017), as cited by Heilbron and Valeriano (2020). In their tectonic model, the first collision (at ca.…”

“…We appreciate Heilbron and Valeriano (2020) for giving us the opportunity to further clarify the tectonic implications of the data presented in Meira, Garcia-Casco, Hyppolito et al (2019) and to discuss the different tectonic interpretations of these new data for the major Brasiliano/Pan-African Ribeira-Araçuaí-West Congo orogenic system, in particular in the context of recent papers that reevaluate the prevailing tectonic models for some Brasiliano/Pan-African orogens (Cavalcante et al, 2019;De Toni et al, 2020;Fossen et al, 2017Fossen et al, , 2020Konopásek et al, 2017Konopásek et al, , 2018Konopásek et al, , 2020Meira et al, 2015;Meira, Garcia-Casco, Hyppolito et al 2019;Meira, García-Casco, Juliani, et al, 2019;Oriolo et al, 2016, among others).…”