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The Novo Progresso Formation, located in southeastern Tapajós Gold Province, at its boundary with the Iriri-Xingu Domain, south of the Amazonian Craton, is composed of quartz-and lithic-arenites and siltstones with volcanic/volcanoclastic contributions, and was deposited in fluvial and lake systems. Reconnaissance detrital zircon U-Pb LA-ICP-MS data on a lithic arenite indicate maximum depositional age around 1840 Ma, whereas structural relationships suggest a minimum age of 1780 Ma. The zircon age spectrum shows two well-defined peaks at 1846 and 1968 Ma, and statistically secondary peaks ranging from 2185 Ma to 2973 Ma. εHf values vary from +8.1 to -14.5 (T DM = 2.13 to 3.95 Ga), whereas the εNd values range from -2.5 to -3.3 (T DM = 2.31 to 3.21 Ga), with one positive value of +4.5 (T DM = 1.81 Ga). These data and the lithological composition indicate that surrounding Orosirian rocks from Tapajós and Iriri-Xingu were the main sources for the sediments, with subordinate contributions from older and more distant domains of the Amazonian Craton. In addition, the Hf systematics suggest a ~2.50 Ga-old crustal growth event and a ~3.95 Ga-old hidden component in the eastern portion of the Amazonian Craton. The deposition of the Novo Progresso Formation is related to the development of the large Orosirian intracratonic rift system known as Uatumã Silicic Large Igneous Province (1.89-1.80 Ga), which cut across the Amazonian Craton, following the final stages of magmatism in the Tapajós Gold Province.

ABSTRACT:The Piriá Basin (Piriá Formation) is a hemi-graben shaped basin that developed over Precambrian rocks of the Gurupi Belt. The lithological content comprises four interfingered lithofacies: (1) arkose and greywacke with pelite layers, (2) laminated siltstones and pelites, (3) arkose with hummocky stratification, and (4) oligomictic conglomerate. This sequence was formed in alluvial fans (conglomerate), and fluvial systems (arkose, greywacke, siltstones and pelites) that were established and evolved during the migration of the subsidence. The sedimentary sequence underwent anquimetamorphism and very weak tectonic deformation. U-Pb analyses of detrital zircon set the maximum depositional age at 591 Ma and indicate several sediment sources, that range in age from the Neoproterozoic to the Archean. The main sources are from the Rhyacian, which is the main period of continental crust formation in the São Luís cratonic fragment and the basement of the Gurupi Belt. Neoproterozoic sources were important in the eastern segment of the basin. Ages from unknown sources in the region so far have also been recorded. Combined, the U-Pb zircon data, the whole-rock geochemical and Sm-Nd results, and the petrographic information revealed proximal felsic to intermediate provenance, in addition to recycled sedimentary sources. As a whole, our data suggest that the Piriá Formation was deposited in a post-orogenic basin related to the final stage of evolution of the Brasiliano cycle of orogenies, which built up the Gurupi Belt. KEYWORDS:Brasiliano/Pan-african cycle; Provenance; Post-orogenic basins; Sedimentology; Gurupi Belt; São Luís craton. RESUMO: