Evolução geológica das sequências do embasamento do Cinturão Araguaia na região de Paraíso do Tocantins (TO), Brasil

Abstract

Isotopic studies based on single zircon Pb-evaporation and Sm/Nd (whole rock) methodologies, allowed advances at the lithostratigraphic scene and geologic evolution of basement, in the south segment of Araguaia Belt. The identified geological processes took place from the Achaean (2.6 Ga and TDM ages varying between 2.78 and 3.25 Ga) through Neoproterozoic Era. The Paleoproterozoic ortognaisses, represented by Rio dos Mangues Complex, are placed between 2.05 and 2.08 Ga, and they were formed from a mantellic and youthful source, with a small crustal contribution where TDM ages are 2.35 e 2.21 Ga. At the end of the Paleoproterozoic, a strong crustal shortening happened, and a partial melting of isolated and thickening compartments were facilitated, generating some igneous bodies (1.85 and 1.82 Ga) and Serrote Granite (1.86 Ga), that comes from sources situated between 2.50 and 2.43 Ga. At the end of the Mesoproterozoic, the region was marked by taphrogenetic processes, evidenced by the appearance of alkaline magmatism (1.05 Ga), beyond depositional basins, amongst which the one that received the sediments that had originated the supracrustals of Araguaia Belt. Through the inversion in the geodynamic conditions, in the Neoproterozoic, a process of horizontal shortening with crustal thickening and distinct volumetric and spatial melting occurred, which may have generated Matança and Santa Luzia Granites. The Araguaia Belt was built from this tectonic motion. The tectonic mass transport in the Amazonian Craton might have occurred, resulting in the current architecture in the form of imbricate fans.