Late Tonian (c. 735 Ma) A-type granite magmatism on the passive margin of the São Francisco paleocontinent was coeval with outboard subduction

[Display omitted] •First geochronology, lithogeochemistry, and isotope data from a Tonian intraplate granite in the Southern Brasília Belt.•Whole-rock geochemistry and isotopic data indicate mixed mantle and crustal sources contributed to granite generation.•A-type granites suggest continental margin extension synchronous with the development of an outboard accretionary orogen. Late Tonian (ca. 735 Ma) A-type granite magmatism accompanied the development of a rifted continental margin in the southwestern portion of the São Francisco paleocontinent. Zircon U-Pb and trace elements, whole-rock lithogeochemistry, and Nd-Sr isotopes enable assessment of the tectonic setting. The Araras Granite shows high silica content (between 73 and 76 %) and ferroan character. The Y + Nb and Yb + Ta parameters vary respectively between 73 to 212 ppm, and 8.3 to 19.1 ppm, and the 1000*Ga/Al ratio varies between 2.6 and 3.4. Zircon U-Pb data indicates a crystallization age of 736 ± 12 Ma. The εNd(t) is slightly negative (between −3.6 and −1.7), and the depleted mantle model ages (TDM) range between 1.26 and 1.56 Ga. Binary mixing models based on whole-rock element and isotope geochemistry indicate that the granite was formed by mixing melts derived from two sources: a lithospheric mantle component and Paleoproterozoic magmatic arc rocks from the regional basement. The Araras Granite is concluded to represent a late stage of extension-related intraplate magmatism between ca. 840 and 730 Ma, associated with the evolution of a rifted continental margin in the southwestern São Francisco paleocontinent. Intraplate magmatism was partially synchronous with documented magmatic pulses within long-lived island arc systems that surrounded the paleocontinent. Extensional episodes in the rifted passive margin may be related to slab-pull forces driven by the outboard subduction dynamics.