Detrital zircon records of the Paleo-Mesoproterozoic rift-sag Tamanduá Group in its type-section, Northern Quadrilátero Ferrífero, Minas Gerais, Brazil

Abstract

The Quadrilátero Ferrífero metallogenetic province is located in the southernmost portion of the São Francisco craton, SE Brazil. The Tamanduá and Cambotas ridges stand out topographically in the northeastern portion of Quadrilátero Ferrífero and show NE-SW and N-S directions, respectively. Those ridges involve metasedimentary rocks of the Tamanduá Group bounded by a fault system. Due to stratigraphic and structural complexities, there is little consensus about the maximum sedimentation age and the stratigraphic position in which Tamanduá Group sediments were deposited. In this work, we took advantage of the excellent exposures in the Tamanduá and Cambotas ridges to present detailed stratigraphic observations combined with U-Pb zircon geochronological data from samples of different stratigraphic levels of Tamanduá Group. Furthermore, we provide U-Pb data from samples of the intrusive Pedra Formosa Suite that cut the whole Tamanduá sequence in the study area. Our observations showed that the Tamanduá Group represents a rift-sag basin-fill succession developed along the eastern border of the São Francisco paleoplate. The basal metaconglomerate and metasandstone package grades upward into marine metasandstone and phyllite. Detrital zircon obtained from the basal unit, Antônio dos Santos Formation, reveals maximum depositional ages between ca. 1981 and 1770 Ma. The upper succession, Cambotas Formation, shows a maximum depositional age from 1769 to 1740 Ma. The Pedra Formosa Suite shows zircons that crystallized at ca. 1740 Ma. The stratigraphic framework and the Orosirian-Statherian ages suggest a correlation with the first rifting event within the São Francisco paleoplate, the precursor of Paleo-to Mesoproterozoic Espinhaço basin.

Depositional setting and U-Pb detrital record of rift-related deposits in the Moeda Formation (Minas Supergroup) at the Gandarela and Ouro Fino synclines, Quadrilátero Ferrífero, Brazil

“…2) is a metasedimentary package that unconformably overlies the RVS. It comprises the Caraça, Itabira, Piracicaba and Sabará groups; the Tamanduá Group has been definitively excluded as a basal unit of the MS and correlated to the Espinhaço Supergroup instead during Paleo-to-Mesoproterozoic (Dutra et al 2020). The Caraça Group, focused on herein, comprises alluvial-fluvial metasandstone, metaconglomerate and metapelite (Moeda Formation) and is overlain by metapelites from a shallow marine environment (Batatal Formation) (Dorr II 1969, Alkmim andMarshak 1998).…”