Cambrian post-collisional overprint recorded by detrital rutile: Insights into the late evolution of the Araçuaí Orogen

Continental to shallow marine sedimentary rocks were deposited along the Brazilian Atlantic margin during the Mesozoic-Cenozoic opening of the South Atlantic Ocean, following the breakup of West Gondwana. Within this context, the Miocene Barreiras Formation provides a key record of sedimentary processes associated with long-term tectono-sedimentary evolution. New detrital rutile U Pb data reveal a distinct Cambrian metamorphic signature at ca. 504 Ma, not previously identified, contrasting with the predominantly Neoproterozoic ages and complex fission-track signatures typically documented in detrital zircon and underscoring the potential of rutile as a complementary provenance and metamorphic tracer. The ca. 504 Ma detrital rutile ages are consistent with the timing of post-collisional collapse in the Araçuaí Orogen (~500–485 Ma), suggesting that this mountain belt constituted the main sediment source for the Barreiras Formation and that the rutile signature reflects the tectonometamorphic history associated with the Brasiliano Orogeny. Comparable Cambrian metamorphic ages reported from Pan-African belts in Angola and Namibia indicate that this thermal pulse extended beyond the Brazilian margin and was part of a broader transcontinental tectonothermal framework. The preservation of Cambrian ages in rutile is compatible with Pb diffusion and partial resetting of the U Pb system during high-grade metamorphism and subsequent lithospheric thinning in the Araçuaí Orogen, processes that record a phase of post-collisional reworking that mechanically weakened the lithosphere. In this sense, the Barreiras Formation not only documents Neogene sedimentary dynamics along the passive margin but also constitutes an archive of deeper crustal processes, bridging the Cambrian post-collisional collapse of the Brasiliano/Pan-African orogenic systems with the later Cretaceous onset of South Atlantic rifting and continental breakup. • Detrital rutile from the Neogene Barreiras Formation was investigated. • Detrital rutile U Pb age reveals a distinct Cambrian metamorphic signature at ca. 504 Ma. • Detrital rutile ages consistent with the timing of post-collisional collapse in the Araçuaí Orogen. • Comparable Pan-African Cambrian ages indicate thermal pulse beyond the Brazilian margin. • Cambrian ages compatible with Pb diffusion and U Pb partial resetting during high-grade metamorphism.