Abstract
The Quadrilátero Ferrífero region is located in the extreme southeast of the Brasiliano São Francisco craton, Minas Gerais state, Brazil. It is composed of (i) Archean TTG granite-gneaissic terranes; (ii) the Archean Rio das Velhas greenstone belt; (iii) the Proterozoic metasedimentary and metavolcano-sedimentary covers. The Rio das Velhas rocks were deposited in the synformal NW–SE-directed Nova Lima basin. The Archean deformation converted the Nova Lima basin into an ample synclinorium with an eastern inverted flank. Archean orogenic gold mineralization within the Rio das Velhas greenstone belt rocks is controlled by NNW–SSE-directed, Archean regional shear zones subparallel to the strata of the Nova Lima synclinorium borders. Transamazonian and Brasiliano orogenies are superposed onto the Archean structures that control gold mineralization. In the eastern domain, Brasiliano fold-and-fault belts prevail, whereas in the western domain Archean and Transamazonian structures abound. The present study focus mainly is the western domain where the Cuiabá, Morro Velho, Raposos, Lamego and Faria deposits are located. Gold orebodies plunge to the E–NE and are tectonically controlled by the Archean D1–D2 deformation. The D3 Transamazonian compression—Which had a SE–NW vector sub-parallel to the regional mineralized Archean foliation/bedding—Buckled these structures, resulting in commonly open, synformal and antiformal regional folds. These are well documented near the gold deposits, with NE–SW axial traces and fold axes plunging to E–NE. Such folds are normal to inverted, NW-verging, with an axial planar foliation dipping moderately to the SE. The Transamazonian compression has only been responsible for the reorientation of the mineralized Archean gold ores, due to coaxial refolding characterized by an opposite tectonic transport. It has therefore not caused any other significant changes. Thrust shear zones, sub-parallel to the strong Transamazonian foliation, have given rise to localized metric segmentation and to the dislocation of gold orebodies. Throughout the region, along the towns of Nova Lima to Sabará, structures pertaining to the Brasiliano Araçuaí orogeny are represented only by gentle folding and by a discrete, non-pervasive crenulation cleavage. Thrust-shear zones and small-scale normal faults have caused, at most, metric dislocations along N–S-oriented planes.
Highlights
The Quadrilátero Ferrífero (QF) metallogenetic province is located in the southern border of theSão Francisco Craton (CSF) [1]
Archean foliation/bedding—Buckled these structures, resulting in commonly open, synformal and antiformal regional folds. These are well documented near the gold deposits, with NE–SW axial traces and fold axes plunging to E–NE
The QF occupies an area of approximately 7000 km2 in the central and southern areas of Minas Gerais state
Summary
The Quadrilátero Ferrífero (QF) metallogenetic province is located in the southern border of theSão Francisco Craton (CSF) [1]. The Quadrilátero Ferrífero (QF) metallogenetic province is located in the southern border of the. The craton is part of the South American Platform, consolidated and Minerals 2020, 10, 983; doi:10.3390/min10110983 www.mdpi.com/journal/minerals. Minerals 2020, 10, 983 stabilized as a result of successive geodynamic cycles. These cycles were, in turn, responsible for the breakdown and re-aggregation of large continental masses over geological time. The QF occupies an area of approximately 7000 km in the central and southern areas of Minas Gerais state. It constitutes the aggregation of Proterozoic and Archean terranes, consolidated at the end of the Minas orogeny, part of the Trasamazonian orogenic cycle. The region is bordered along its eastern and southeastern limits by the Araçuaí orogenic belt (Brasiliano orogenic cycle) (Figure 1)
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