Provenance of the Late Ediacaran Minas de Corrales Formation, Nico Pérez Terrane, Uruguay: paleogeographic implications

The Nico Pérez Terrane, located in the eastern margin of the Río de la Plata Craton, played a critical role in the assembly of SW Gondwana. The Isla Cristalina de Rivera basement klippe represents the northernmost exposures of the Nico Pérez Terrane in Uruguay, where the metavolcanic-sedimentary Minas de Corrales Formation represents the only preserved Ediacaran supracrustal cover. The provenance analyses of this key succession have unraveled the crustal signature and ages of its sources, providing constraints on the paleogeography and tectonic evolution of the Arachania subduction-related orogeny that developed along the eastern margin of the Río de la Plata Craton. We compare it to other coeval extensional basins in a back-arc position regarding Arachania linked to the opening of the Brazilides Ocean. Detrital mineral quantification and whole-rock geochemistry of the Minas de Corrales Formation indicate that the bulk of the detritus was rapidly sourced from basement rocks, with a composition similar to average unrecycled upper continental crust, with influences of a less differentiated component. Nd isotopes further suggest a Mesoproterozoic mantle extraction age for the juvenile component of the metavolcanic sandstones. Detrital zircon patterns of all studied samples point to diverse source rock ages: one metasandstone displays a dominance (95%) of Siderian–Rhyacian ages, whereas the other shows a concentration of Tonian to Cryogenian ages (89%); the metavolcanic sandstones yield main populations of Rhyacian, Calymmian, and Ectasian ages. All provenance indicators suggest that the Ediacaran Mina de Corrales Formation was fed from Paleoproterozoic and Neoproterozoic basement sources that likely comprised the rift-shoulders and nearby areas; these sources are traced to the Taquarembó, Tijucas, São Gabriel, and Nico Pérez Terranes. The Minas de Corrales Formation was deposited in an extensional basin emplaced on the eastern margin of the Río de la Plata Craton that developed during the opening of the Brazilides Ocean.