Stratigraphy, petrography and tectonics of the manganese-bearing Buritirama Formation, Northern Carajás Domain, Amazon Craton

Abstract

The Buritirama Formation (BF) occurs at the extreme north of the Carajás Province, close to the contact with the Bacajá domain, in the southeastern portion of the Amazon Craton (Brazil). The BF consists of a 40 km long, ca. 3 km wide NW-SE trending structure arranged in four imbricated thrusts that individualize three main stratigraphic units. The lower unit is composed of orthoquartzite followed by carbonate-silicate rocks. The intermediate unit hosts a supergene manganese ore deposit formed by weathering of kutnohorite-rich marble. Quartzite/ mica-quartz schist followed by carbonate-silicate rocks make up the upper unit. The local basement is constituted by orthogneiss-migmatite (Xingu Complex) and the Buritirama metagranite. Mineral chemistry data and metamorphic textures record high consumption of carbonate and quartz to produce clinopyroxenes. The structural assemblage of the BF records mass transport from NE to SW and the following deformational phases: D1 (compressional ductile), D2 (compressional brittle) and D3 (extensional brittle). The BF is interpreted as part of a platformal depositional system positioned at the border of the Carajás domain, which was probably inverted, deformed and metamorphosed during the Transamazonian event (ca. 2.1 Ga), in a deformation belt related to the amalgamation between the Carajás and Bacajá domains.

Unraveling sedimentary precursors and metal enrichment of high-grade metamorphosed manganese-rich rocks from the Borborema Province, northeastern Brazil

“…In Brazil, similar manganese deposits also exist containing proven reserves up to 43 Mt of ore (Chisonga et al, 2012). These deposits share similar age and geological setting with the aforementioned African fields (Roy, 2006;Chisonga et al, 2012;Cabral et al, 2019a;Salgado et al, 2019). For example, the location of the current study is believed to have a common paleographical provenance as the West African Craton (Klein and Moura, 2008;Costa et al, 2018;Grenholm, 2019;Grenholm et al, 2019).…”

“…This orogeny was a promising candidate to trigger the high-grade metamorphism imprinted in these rock fragments. As a consequence of this process, other Paleoproterozoic manganese-rich rocks from South America and West Africa share some similar features to the Brazilian rocks in terms of mineral assemblage and metamorphic grade (e.g., Mücke et al, 1999;Chisonga et al, 2012;Borges et al, 2015;Cabral et al, 2019a;Rodrigues et al, 2019a, b;Salgado et al, 2019). In this setting, the best correlation maybe with the Serra do Navio manganese deposit in the Amazonian Craton (Chisonga et al, 2012) and the manganese ores at Morro da Mina, in the southern Quadrilátero Ferrífero (Cabral et al, 2019a).…”