Investigating assembly timing of Ediacaran Serra dos Órgãos batholith – Hints on prolonged magmatism at Ribeira belt, SE Brazil

• Published in: Journal of South American earth sciences Vol. 120; p. 104053
• Main Authors: Fernandes, Clarisse Monteiro, Mendes, Julio Cezar, Duffles Teixeira, Patrícia Anselmo, Romero da Silva, Luiz Felipe
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2022
• Subjects: Araçuaí-ribeira orogenic system; Serra dos órgãos batholith; Syn-to late-collisional magmatism; Zircon U–Pb geochronology; Zircon U–Pb geochronology; Serra dos órgãos batholith; Araçuaí-ribeira orogenic system; Syn-to late-collisional magmatism
• ISSN: 0895-9811; 1873-0647
• DOI: 10.1016/j.jsames.2022.104053

The Pan-African/Brasiliano orogeny, result of the West-Gondwana assembly from the Neoproterozoic to Ordovician, had produced the Ribeira and Araçuaí belts at the edges of the São Francisco and Congo cratonic margins. In the central Ribeira belt, the docking of accretionary systems to the reworked continental margin of the São Francisco paleoplate culminated in a complex Ediacaran granite production event. Syn-to late-collisional I- and S-type granites and hybrid granitoids intruded the reworked margins and accreted continental masses, as well as the Tonian to Ediacaran juvenile magmatic arcs represented by the Serra da Prata and Rio Negro Complexes. The Serra dos Órgãos batholith is the main intrusion emplaced at the juvenile crust, forming an elongated NE-SW trending tabular body that crops out in the highland region of Rio de Janeiro State, Southeast Brazil. Geochemical and geochronological data in addition to field and petrological evidence was gathered to explore the assembly timing of the SOB granitic end-member. Zircon U–Pb SHRIMP and LA-ICP-MS geochronological data yield a prolonged emplacement timelapse for the studied granites and, along with published U–Pb ages of the SOB granodioritic end-member, enable the characterization of the Serra dos Órgãos as a composite batholith. The wide time interval of heat input inside intermediate crust is consistent with a prolonged, slow-cooling hot orogenic belt model for the Araçuaí-Ribeira Orogenic System. •Serra dos Orgãos batholith was emplaced from syn-to late-collisional stage of Ribeira belt.•Serra dos Orgãos granitic member was assembled at ca. 585–595 Ma, during syn-collisional stage.•The emplacement time previously established for the Serra dos Órgãos batholith was extended in at least 20 Myr.•The extensive emplacement interval for Serra dos Orgãos magmatism is consistent with a proposed long-term, slow-cooling hot orogen.