Tectono-sedimentary evolution of the Paleoproterozoic succession of the Carajas Basin, southeastern Amazonian Craton, Brazil: Insights from sedimentology, stratigraphy, and U-Pb detrital zircon geochronology

The Carajas Basin, situated in the southeastern Amazonian Craton in northern Brazil, hosts a > 6 km thick pile of volcano-sedimentary rocks deposited from the Neoarchean to the early Paleoproterozoic eras (ca. 2.75-2.06 Ga). It is claimed that this basin started as a rift configuration in which volcanic and banded iron formation strata were deposited during the Neoarchean Era. However, the tectono-sedimentary evolution of this basin through the Paleoproterozoic Era remains unexplored. Based on a sedimentological, stratigraphic, and U-Pb detrital zircon geochronological investigation of a marine to a fluvial succession of this basin, this study suggests that the Carajas Basin evolved in a foreland setting during the early Paleoproterozoic Era. Probably, the Carajas Foreland Basin was sedimented in the underfilled stage (ca. 2.5-2.3 Ga) by deep-marine strata (i.e., glaciogenic submarine fan deposits), likely from the Siderian-Rhyacian Serra Sul Formation. Subsequently, shallow-marine deposits of the Azul Formation were deposited in the filled stage (ca. 2.3-2.1 Ga), followed by deposition of the fluvial to alluvial deposits of the Aguas Claras and Gorotire formations during the overfilled stage (ca. 2.1-1.9 Ga). The Azul and Aguas Claras formations were supplied mainly by Meso- to Neoarchean source rocks, whereas Paleoproterozoic and Paleoarchean rocks played the role of a subordinate source of sediments. The youngest U-Pb age cluster, at ca. 2.27 Ga, is interpreted as its maximum depositional age. In terms of paleogeography, the occurrence of Rhyacian zircon grains in the Azul Formation deposits suggests, at least partially, a connection between the Carajas Protocontinent with the Bacaja Domain during that period. The integrated data corroborate the hypothesis that the foreland basin was formed in a scenario of collision between the Bacaja Domain and the Carajas Protocontinent during the Transamazonian Cycle. These dramatic upheavals are directly related to the configuration of the Columbia Supercontinent, which initially led to the emergence of the Carajas Foreland Basin, and soon after, the cratonization of proto-Amazonia