Proveniência de sedimentos do Membro Acácias da Formação Resende: idades de U- Pb/Lu-Hf (LA-ICP-MS) em zircões detríticos e MEV-CL combinada com microscopia óptica em quartzo detrítico

• Autor(a) principal: Oliveira, Carlos Eduardo Sales de
• Data de Publicação: 2019
• Outros Autores: [e-mail]
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/19761
• topic: Bacia de Resende; Quartzo detrítico; Zircão detrítico; Geocronologia; Proveniência; Resende basin; Detrital quartz; Detrital zircon; Geochronology; Provenance; CIENCIAS EXATAS E DA TERRA::GEOCIENCIAS::GEOLOGIA

The Resende Basin is an eocene-oligocene oriented ENE-WSW hemigraben located in the central segment of the Ribeira Range, a geotectonic unit made up of deformed and metamorphic proterozoic rocks during the Brasiliano orogenesis. The Resende Formation corresponds to the main sedimentary fill of the basin. This includes the traditional Resende Formation, Itatiaia Member and Acácias Member. The present work, through combined analyzes of U-Pb and Lu-Hf by the analytical technique LA-ICP-MS in detrital zircons, and combined analyzes of scanning-cathodoluminescence electron microscopy (SEM-CL) and detrital quartz optical microscopy, present data that enable interpretations of the Acacia Member sediment provenance. Five layers of fine to coarse grained arcosian sandstone were sampled from the Acacias Member stratotype.Probability histograms, obtained through the U- Pb ages of detrital zircons, show a predominant contribution from Neoproterozoic sources (60%), followed by Paleoproterozoic sources (34%). Mesoproterozoic (4%) and Archean (2%) sources have a subordinate contribution. No detrital zircon crystals of ages corresponding to alkaline intrusive rocks were found. The results of Lu-Hf analysis show that most Neoproterozoic crystals have negative values of ɛHf, suggesting enriched source, while a smaller part have positive values, suggesting juvenile magmatic source. The crystals of Mesoproterozoic, Paleoproterozoic and Archene have a more balanced distribution in relation to the Hf values, with a slight domain of positive values. The results obtained by the detrital quartz analysis show the predominance of metamorphic quartz (90%) over plutonic quartz (10%).The results obtained were interpreted based on the geotectonic development context of the Resende Basin and the lithologies present in the basement. Potential neoproterozoic sources consist of granitoid bodies located in the basement south of the Resende basin, with greater importance being given to the Rio Turvo granitoid. The possible paleoproterozoic sources are metasedimentary rocks of the Embu Complex, Juiz de Fora, Andrelândia and Paraíba do Sul, located in the south basement of the studied region, as well as Quirino Complex orthognaisses and orthogranulites belonging to the Juiz de Fora Complex.