Abstract
Abstract The Quadrilatero Ferrifero metallogenetic province is located in the southernmost portion of the Sao Francisco craton, SE Brazil. The Tamandua and Cambotas ridges stand out topographically in the northeastern portion of Quadrilatero Ferrifero and show NE-SW and N-S directions, respectively. Those ridges involve metasedimentary rocks of the Tamandua 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 Tamandua Group sediments were deposited. In this work, we took advantage of the excellent exposures in the Tamandua and Cambotas ridges to present detailed stratigraphic observations combined with U-Pb zircon geochronological data from samples of different stratigraphic levels of Tamandua Group. Furthermore, we provide U-Pb data from samples of the intrusive Pedra Formosa Suite that cut the whole Tamandua sequence in the study area. Our observations showed that the Tamandua Group represents a rift-sag basin-fill succession developed along the eastern border of the Sao Francisco paleoplate. The basal metaconglomerate and metasandstone package grades upward into marine metasandstone and phyllite. Detrital zircon obtained from the basal unit, Antonio 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 Sao Francisco paleoplate, the precursor of Paleo- to Mesoproterozoic Espinhaco basin.
Highlights
In Proterozoic times, several sedimentary basins are registered in the interior and the boundaries of the Neoproterozoic São Francisco craton (SFC), southeastern Brazil (e.g., Alkmim and Martins-Neto 2012, Guadagnin and Chemale Jr. 2015)
The first one is associated with Antônio dos Santos Formation, an early intracontinental rifting sedimentation that was succeeded by a flexural stage, characterized by the rapid deposition of Cambotas Formation (Fig. 11)
The first one is associated with Antônio dos Santos Formation, an early intracontinental rifting sedimentation succeeded by a flexural stage, characterized by the rapid deposition of the Cambotas Formation;
Summary
In Proterozoic times, several sedimentary basins are registered in the interior and the boundaries of the Neoproterozoic São Francisco craton (SFC), southeastern Brazil (e.g., Alkmim and Martins-Neto 2012, Guadagnin and Chemale Jr. 2015). The intracratonic basins (Fig. 1) comprise several sedimentary sequences separated by unconformities as the main result of continuous and significant changing patterns of intraplate tectonic regimes (Alkmim and Martins-Neto 2012). The early proposal points to the correlation of the Tamanduá Group with the QF units, i.e., Archean Rio das Velhas greenstone belt or NeoarcheanRyacian Minas Supergroup. The SFC comprises Archaean nuclei, Archean-Proterozoic metavolcanic-sedimentary sequences, and Paleoproterozoic arc-related granitoids that host several sedimentary basins from the Proterozoic to Phanerozoic and are surrounded by Neoproterozoic orogenic belts (Fig. 1) (Almeida 1977, Alkmim and Martins-Neto 2012). In the QF, the Archean kernels are formed by domal igneous-metamorphic complexes encircled by the Rio das Velhas greenstone belt (i.e., dome‐and‐keel province; Cutts et al 2019) and partially covered by the Paleoproterozoic Minas basin (Fig. 3).
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