Anatomy of the transpressional Dom Feliciano Belt and its pre-collisional isotopic (Sr–Nd) signatures: A contribution towards an integrated model for the Brasiliano/Pan-African orogenic cycle |
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| Institution: | 1. Universidade Federal Do Pampa (Unipampa), Campus Caçapava Do Sul, Av. Pedro Anunciação, 111, 96570‑000 Caçapava do Sul, RS, Brazil;2. Programa de Pós-Graduação em Geociências, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves, 9500, 91500-000 Porto Alegre, RS, Brazil;3. Programa de Pós-graduação em Geologia (PPGGeologia), Universidade Federal de Santa Catarina (UFSC), R. Eng. Agronômico Andrei Cristian Ferreira, s/n, 88040-900 Florianópolis, SC, Brazil;4. Instituto de Ciência e Tecnologia, Universidade Federal dos Vales do Jequitinhonha e Mucuri, Rodovia MGT 367 – Km 583, 5000, 39100-000 Diamantina, MG, Brazil;1. Instituto de Geociências, Universidade de São Paulo, Rua do Lago 562, 05508-80, São Paulo, Brazil;2. Instituto de Geociências, Universidade Federal da Bahia, R. Barão de Jeremoabo, s/n, 40170-290, Salvador, Brazil;1. National Observatory (ON), Geophysics Department, Ministry of Science, Technology and Innovation, Rio de Janeiro, Rio de Janeiro, Brazil;2. Federal University of Pampa (Unipampa), Applied Geophysics Laboratory (LGA), Rio Grande do Sul, Caçapava do Sul, Brazil;3. Post-Graduate Program in Geology, Federal University of Paraná (UFPR), Paraná, Curitiba Brazil;4. State University of Rio de Janeiro (UERJ), Physics Institute, Rio de Janeiro, Brazil;1. Gerência de Geologia e Recursos Minerais, Serviço Geológico Do Brasil (SGB – CPRM), Rua Banco da Província 105, 90840-030, Porto Alegre, Rio Grande do Sul, Brazil;2. Programa de Pós-graduação Em Geociências, Universidade Federal Do Rio Grande Do Sul, Avenida Bento Gonçalves 9500, 91500-000, Porto Alegre, Rio Grande do Sul, Brazil;1. Department of Geosciences, UiT–The Arctic University of Norway, Dramsveien 201, 9037 Tromsø, Norway;2. Czech Geological Survey, Klárov 3, 118 21 Prague 1, Czech Republic;3. Institute of Geology of the Czech Academy of Sciences, Rozvojová 269, 165 00 Prague 6, Czech Republic;4. Programa de Pós-graduação em Geologia (PPGGeologia), Universidade Federal de Santa Catarina (UFSC), Florianópolis, SC, Brazil;5. Programa de Pós-graduação em Geociências, Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil |
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| Abstract: | The Dom Feliciano Belt evolution is reviewed based on cross-sections, space–time diagrams, P-T paths, and Sr–Nd isotopic data of pre-collisional metaigneous rocks. The belt is divided into northern, central and southern sectors, subdivided into tectonic domains, developed at Neoproterozoic pre-, syn- and post-collisional stages. The northern sector foreland pre-collisional setting represents a rift, with tholeiitic (meta)volcanic rocks (∼800 Ma) chronocorrelated to hinterland intermediate and acidic orthogneisses of high-K calc-alkaline arc signature. In contrast, the central sector records a complete section from the forearc towards the back-arc region during pre-collisional times. In the western domain, ophiolites (∼920 Ma) are associated with arc-related orthogneisses and metavolcanic rocks (880–830 Ma; 760–730 Ma). At back-arc position, continental arc-related magmatism (800–780 Ma) is registered by hinterland orthogneisses and central foreland metavolcanic rocks. Ophiolites on the hinterland opposite side comprise two compositional groups, with N-MORB and supra subduction signature, interpreted as a back-arc basin record (∼750 Ma). The pre-Neoproterozoic basement of the whole belt is correlated with the Nico Perez Terrane and Luis Alves Block (Archean to Mesoproterozoic, with Congo Craton affinity). This contrasts with the Piedra Alta Terrane (Rio de La Plata Craton, only Paleoproterozoic), westernmost Uruguay. The suture between the Piedra Alta and Nico Perez terranes is correlated with the suture zone in the westernmost central sector. Transpression affected both foreland and hinterland during collision (660–640 Ma), with high-T/low-P hinterland progressive exhumation, whilst foreland low- to medium-grade correlated sequences record underthrusting. Post-collisional processes included magmatism throughout the belt (640–580 Ma), strain partitioning along strike-slip shear zones, and foreland basin fill. Late tectono-metamorphic and magmatic processes (560–540 Ma) were attributed to the Kalahari Craton collision. Arc magmatism migration due to subduction angle variations suggests modern-style plate tectonics during Gondwana amalgamation. Diachronism and kinematic inversion are characteristic of an oblique convergent multi-plate orogenic system. |
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| Keywords: | Orogenesis Gondwana Arc magmatism Back-arc P-T paths |
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