Zircon U–Pb and Lu–Hf Evidence for an Orosirian Terrane with a Neoarchean Component in the Southern Araguaia Belt: Implications for a Possible Crustal Collage in the Eastern Amazonian Craton

The crustal domains of the southern Araguaia Belt in Brazil reveal a complex history of crustal growth and reworking during West Gondwana assembly. While some of these domains show an affinity with the Amazonian Craton, the tectonic evolution of others remains poorly understood. To address this issue, we present U–Pb and Lu–Hf zircon data from gneisses of the Rio dos Mangues and Porto Nacional complexes. The eastern part of the Rio dos Mangues Complex records ages of 1.90–1.91 Ga and 2.51 Ga and a Lu–Hf isotopic signature suggesting derivation from long-lived ancient crustal reservoirs (strongly negative ƐHf(t) values and Hf-TDMC ages of 3.69–4.32 Ga). This contrasts with the ca. 2.06 Ga age and Lu-Hf signature (possible mixing of Paleoproterozoic juvenile material with a Mesoarchean crustal source) of its western portion. We recognize an isotopically distinct Orosirian crustal domain containing Neoarchean remnants, herein referred to as the Pau D’Arco Complex. Gneisses of the Porto Nacional Complex are ca. 2.15 Ga and have a Lu–Hf isotopic signature indicating Paleo- to Mesoarchean crustal sources, consistent with previously reported data for the associated granulites. Therefore, our geochronological and isotopic dataset indicates three distinct crustal domains in the southern Araguaia Belt.