A-type tonian granite in the northwest of the gavião block: Record of within-plate magmatism precursor to the continental rifting of the São Francisco paleoplate?

The Early Tonian period in the São Francisco Craton represents the development of an intracontinental rift across the northern and central Espinhaço regions, playing a crucial role in understanding the tectonic evolution of the Neoproterozoic Period within this craton and its adjacent orogens. This...

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Bibliographic Details
Published in:	Journal of South American earth sciences Vol. 141; p. 104948
Main Authors:	Vale, José Alberto Rodrigues do, Uchôa Filho, Evilarde Carvalho, Pedrosa Junior, Nilo Costa, Sousa, Francisco Rubens de, Barros, Renato de Assis, Carvalho, Ciro Duarte de, Freitas, Magno de Sá, Rezende, Eduardo Soares de, Silveira, Douglas Almeida
Format:	Journal Article
Language:	English
Published:	Elsevier Ltd 01-08-2024
Subjects:	A-type granite Continental rifting Geochemistry São Francisco craton Tonian magmatism U-Pb geochronology Geochemistry Tonian magmatism U-Pb geochronology São Francisco craton A-type granite Continental rifting
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Summary:	The Early Tonian period in the São Francisco Craton represents the development of an intracontinental rift across the northern and central Espinhaço regions, playing a crucial role in understanding the tectonic evolution of the Neoproterozoic Period within this craton and its adjacent orogens. This rift is associated with the breakup of the São Francisco paleoplate, marked by the formation of several rifts, some of which were aborted (e.g. Santo Onofre Rift), and magmatism associated. Field investigations, coupled with petrographic, lithogeochemical, and U–Pb geochronological data of the Serra do Meio Suite, elucidate key characteristics and offer significant insights into the Tonian tectonic evolution of the São Francisco Craton and its relationship with Santo Onofre Rift. The suite comprises metagranitoids exhibiting a mineralogical composition spanning from alkali-feldspar granites to granites and its petrogenesis and tectonic characteristics reveal an alkaline to calc-alkalic signature, exhibiting extreme ferroan geochemistry and indications of moderate to high oxygen fugacity. Pressure estimations suggest low-pressure conditions during magma crystallization, implying shallow crustal emplacement. The suite's evolution involves complex petrogenetic processes, likely influenced by fractional crystallization and contamination by country rocks from a quartz-feldspathic crustal source, as well as a possible contribution from juvenile tholeiitic mantle sources associated with rift environments, showcasing a signature typical of A1-type granite. The U–Pb SHRIMP age, determined as 930 ± 2 Ma (MSWD = 0.34), is interpreted as the crystallization age of the rock and allows us to connect it to the opening of the Santo Onofre-Macaúbas Rift in the São Francisco Craton. •The Serra do Meio Suite (930 Ma) contains an A-type magmatism in the São Francisco Craton.•Origin tied to quartzofeldspathic partial melting, with mantle input and crustal assimilation.•Tonian rifting links A-type magmatism with São Francisco's paleoplate breakup.•This Suite represents a continental rifting stage within the precursor Santo Onofre basin.
ISSN:	0895-9811 1873-0647
DOI:	10.1016/j.jsames.2024.104948