Geochemical, geochronological, and isotopic constraints for the Archean metamorphic rocks of the westernmost part of the Carajás Mineral Province, Amazonian Craton, Brazil

• Published in: Journal of South American earth sciences Vol. 110; p. 103340
• Main Authors: Fernandes, Carlos Marcello Dias, Galarza, Marco Antonio, de Gouvêa, Rodrigo César Teixeira, de Souza, Hugo Paiva Tavares
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.10.2021
• Subjects: Geochemistry; Gneiss; Shear zone; São Félix do Xingu; Tectonics; Geochemistry; São Félix do Xingu; Tectonics; Gneiss; Shear zone
• ISSN: 0895-9811; 1873-0647
• DOI: 10.1016/j.jsames.2021.103340

The Archean nucleus of the Amazonian Craton, represented by the Carajás Mineral Province (northern Brazil), crops out as a broad exposition of igneous, sedimentary, and metamorphic rocks showing a complex polyphase geologic history. A succession of orthogneisses (metagranitoids), amphibolites, and metavolcano-sedimentary rocks that show greenstone belt characteristics occur in Tancredo Neves Village district, northeast of São Félix do Xingu city (state of Pará), is the focus of this study. Detailed field, petrographic, and stratigraphic data reveal that these metamorphic rocks underwent two different tectono-metamorphic events: (i) the regional metamorphism (>2.8 Ga), which occurred under greenschist-to mid-upper amphibolite-facies conditions; and (ii) the dynamic metamorphism (>2.6 Ga) which reached amphibolite-facies conditions and overprinted previous metamorphic textures. Associated regional strike-slip NW–SE to EW-trending ductile shear zones generated mylonitic, ultra-mylonitic, and migmatitic zones. Whole-rock geochemistry discriminates four groups of metagranitoid protoliths. G1 group is composed of peraluminous trondhjemitic rocks samples, calc-alkaline, weakly fractionated, and enriched in HREE. G2 group comprises metaluminous and alkaline monzogranite samples with high Zr, Y, Nd, HREE, and intermediate fractionation. U–Pb (LA-MC-ICP-MS) dating of G2 zircons yields a crystallization age of 2745.6 ± 5.0 Ma. Groups G3 and G4 encompass peraluminous, calc-alkaline to alkali-calcic, anorogenic, fractionated monzogranitic and granodioritic rocks. G3 and G4 groups are further distinguished by high and low La/Yb(N) ratios, respectively. The results obtained for Tancredo Neves Village district very much resemble the Canaã dos Carajás (Carajás Mineral Province) area characteristics, comprising intense magmatism (2.7–3.0 Ga) and reworking related to at least two distinct metamorphic events in the Archean. As Canaã dos Carajás, Tancredo Neves Village can be a promising area for mining exploration. •Comprises the Archean rocks from the Tancredo Neves Village region, northern Brazil.•Geological, petrographical, and geocronological data for mylonitic gneissic granitoids.•Definition of a regional large-scale metamorphic event transposed by a dynamic event.•Petrogenetic features and comparisons with the easternmost Carajás Mineral Province.