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

Silas Santos Salgado,Marco Paulo De Castro,Glaucia Nascimento Queiroga,Fabrício De Andrade Caxito

doi:10.1590/2317-4889201920180106

Silas Santos Salgado, Marco Paulo De Castro + Show 2 more

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https://doi.org/10.1590/2317-4889201920180106

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Abstract

The Buritirama Formation (BF) occurs at the extreme north of the Carajas Province, close to the contact with the Bacaja 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 Carajas 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 Carajas and Bacaja domains.

Highlights

The Carajás province (3000–2500 Ma) is the oldest part of the Amazon craton and it is located in the southeastern Pará state, north of Brazil (Santos et al 2000, Santos 2003)
We presented preliminary insights in an attempt to elucidate the meaning of the Buritirama Formation in the amalgamation between the Carajás and Bacajá blocks
The Itacaiúnas River defines its southeast border where the ridge ends in an anticlinal structure with the Buritirama metagranite in its core. It is thrust over the Xingu Complex orthogneisses (Carajás domain), and to the northeast, a quartz, iron-rich shear zone marks the contact between the Buritirama Formation (BF) and the probably Bacajá domain (Figs. 3A and 3B)

Summary

Introduction

The Carajás province (3000–2500 Ma) is the oldest part of the Amazon craton and it is located in the southeastern Pará state, north of Brazil (Santos et al 2000, Santos 2003). It comprises one of the largest mineral provinces of the world (Carajás Mineral Province), hosting world-class deposits of iron, copper, and gold (DOCEGEO 1988, Grainger et al 2008). The province was subdivided into the essentially Neoarchean Carajás domain (northern portion) and the Mesoarchean Rio Maria domain (southern portion; Gibbs et al 1986, Machado et al 1991, Santos 2003, Vasquez & Rosa-Costa 2008, Dall’Agnol et al 2013)

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