The Archean Paleoproterozoic evolution of the Quadrilatero Ferrífero
(Brasil): Current models and open questions

ALBERT, CAPUCINE; MOREIRA, HUGO; ALKMIM, FERNANDO; FARINA, FEDERICO; AGUILAR GIL, CARMEN MARÍA; CUTTS, KATHRYN; MARTÍNEZ DOPICO, C.I.; HIPPERTT, JOAO P; LANA, CRISTIANO

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2016 vol. 68 p. 4 - 21

0895-9811

The Quadrilatero Ferrífero is a metallogenic district (Au, Fe, Mn) located at the southernmost end of theS~ao Francisco craton in eastern Brazil. In this region, a supracrustal assemblage composed of Archeangreenstone and overlying NeoarcheanePaleoproterozoic sedimentary rocks occur in elongated keelsbordering domal bodies of Archean gneisses and granites. The tectonomagmatic evolution of theQuadrilatero Ferrífero began in the Paleoarchean with the formation of continental crust between 3500and 3200 Ma. Although this crust is today poorly preserved, its existence is attested to by the occurrenceof detrital zircon crystals with Paleoarchean age in the supracrustal rocks. Most of the crystallinebasement, which is composed of banded gneisses intruded by leucogranitic dikes and weakly foliatedgranites, formed during three major magmatic events: Rio das Velhas I (2920e2850 Ma), Rio das VelhasII (2800e2760 Ma) and Mamona (2760e2680 Ma). The Rio das Velhas II and Mamona events represent asubduction-collision cycle, probably marking the appearance of a modern-style plate tectonic regime inthe Quadrilatero Ferrífero. Granitic rocks emplaced during the Rio das Velhas I and II events formed by mixing between a magma generated by partial melting of metamafic rocks with an end member derivedby recycling gneissic rocks of older continental crust. After deformation and regional metamorphism atca. 2770 Ma, a change in the composition of the granitic magmas occurred and large volumes of high-Kgranitoids were generated.The ca. 6000 m-thick Minas Supergroup tracks the opening and closure of a basin during the NeoarcheanePaleoproterozoic,between 2600 and 2000 Ma. The basal sequence involves continental tomarine sediments deposited in a passive margin basin and contain as a marker bed the Lake SuperiortypeCaue Banded Iron Formation. The overlying sediments of the Sabar ^ a Group mark the inversion of the basin during the Rhyacian Minas accretionary orogeny. This orogeny results from the collision betweenthe nuclei of the present-day S~ao Francisco and Congo cratons, generated the fold-and thrust beltstructure of the Quadrilatero Ferrífero. Afterwards, the post- orogenic collapse resulted in the depositionof the Itacolomi Group and in the genesis of the dome-and-keel structure.In this paper, we review current knowledge about the 1500 Ma long-lasting tectonomagmatic andstructural evolution of the Quadrilatero Ferrífero identifying the most compelling open questions andfuture challenges.