Late Tonian within-plate mafic magmatism and Ediacaran partial melting and magmatism in the Costeiro Domain, Central Ribeira Belt, Brazil

Abstract

The tectonic evolution of the Ribeira Belt comprises a protracted history involving several magmatic, deformational and metamorphic events mainly associated with the Neoproterozoic Brasiliano Orogenic Cycle. Most tectonic models relate the evolution of the Ribeira Belt to a protracted orogenic history with diachronous accretion of different terranes against larger cratonic blocks. However, recent proposals challenge models of multi-stage terrane accretions. In this paper we revisit the current tectonic models proposed for the Central Ribeira Belt, based essentially on a large data compilation and new geochemical and geochronological data from samples of the Costeiro Complex. The critical evaluation of these data indicates a long-lasting shared evolution for two geological domains in the Central Ribeira Belt (Embu and Costeiro Domains), usually thought to be different terranes accreted during the late Ediacaran. The first report of late Tonian within-plate tholeiitic to alkaline mafic magmatism and the late Cryogenian-early Ediacaran metamorphism in the Costeiro Complex support the interpretation of shared evolution on both Embu and Costeiro Domains, challenging the current models of diachronous accretion of terranes during the late Ediacaran in the Central Ribeira Belt.