Abstract
The Manda Saia granite occurs in the Carajás province, southeastern Amazonian craton, and it is represented by two semicircular intrusive stocks in the Mesoarchean granitoid and greenstone belt sequence of the Rio Maria domain. The stocks are composed of hololeucocratic, red-colored monzo- and syenogranite rocks. Biotite is the main ferromagnesian mineral, and amphibole is rare and was formed later. The rocks are ferroan, calk-alkalic, peraluminous and present a restricted and high SiO2 range (74.80 and 77.70%), high FeOt/FeOt+MgO (0.89–0.98) ratios and enrichment in rare earth elements (REEs, 111–497 ppm), with moderate negative Eu anomalies (0.04–0.63). The plutons are classified as ferroan A-type granites and were formed under moderately reduced to moderately oxidized conditions, similar to those those in the Serra dos Carajás suite. They also show affinities with the more evolved members from both the reduced Velho Guilherme suite and oxidized Jamon suite from the Carajás province. The Manda Saia granite has a zircon U-Pb crystallization age of 1866 ± 10 Ma and is derived from partial melting of the Mesoarchean crust of tonalitic composition, as indicated by strongly negative ƐHf values (−12 to −18). The emplacement of these plutons is related to extensional tectonics with magma transport at shallow crustal levels.
Published Version
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