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The Demeni-Mocidade domain (DMD) comprises a large area of granitoid rocks, located on the border between the states of Roraima and Amazonas, Brazil, within the inner part of the Ventuari-Tapajos Province of the Amazonian Craton, where large amounts of granitoid rocks, formed between 2.0-1.8 Ga, are predominant. This study examines six granite samples collected from the Mocidade and Demeni mountains, which are related in time to the Uatuma Silicic Large Igneous Province (SLIP), which, in turn, covers several tectonostratigraphic domains whose evolution is associated with an intercontinental setting, allowing a common association with I- and A-type granitoid rocks formed within the same 1.88 to 1.87 Ga time interval. These rocks are monzogranites and correspond petrographically to holocrystalline anisotropic lithotypes with fine to medium grain sizes. Their textural relationships, including some lithotypes containing phenocrysts with oscillatory zoning and resorbed rims, indicatethat crystallization occurred at subvolcanic or hypabyssal depths. Moreover, the association between plutonic and subvolcanic rocks in the same suite shows variations in the crustal development of the magmatic chambers. The granitoids of the DMD share a common geochemical signature with those of the Agua Branca Suite, which occurs within the Uatuma and Trombetas-Erepecuru domains of the Guiana Shield, suggesting that their crystallization occurred in similar magmatic chambers. Six U-Pb zircon ages show that most zircon crystals are concordant and the few ones which are discordant are well aligned along Discordia straight lines descending to zero. The calculated Concordia ages, covering the 1884 to 1877 Ma interval, agree within experimental error, indicating a probably similar crystallizationage. Such apparent age values, close to 1900 Ma for the DMD, made it possible for the domain of the Uatuma SLIP to spread to the West, and the area of the Ventuari-Tapajos Province could extend towards the Amazonas State of Venezuela. Finally, the coexistence between I- and A-type granitoids in the DMD, with ages within the range 1.88-1.87 Ga, stimulates a discussion, and there are three possibilities: (1) The calc-alkaline magmatism can be associated with late (post-collisional) processes related to subduction. (2) The granitoid rocks are formed in an intracontinental setting under more stable (post-orogenic) tectonic conditions. (3) The granitoid rocks are predominantly formed by A-type and alkaline magmatism in intraplate settings.

Orogenic Au deposits represent one of the largest sources of gold in the world and in Brazil, particularly at the Quadrilatero Ferrifero, southeastern portion of the Sao Francisco Craton. In the last decades, advances in in-situ analytical techniques allowed a detailed investigation of the chemistry of sulfides. This can reveal information about the origin and composition of the mineralizing fluids, potential sources of metals and sulfur and the fluid-rock interaction during the ore-forming processes. In this paper we combine Electron Microprobe Analysis and LA-ICP-MS analyses to put constraints on the nature and evolution of the Pitangui gold deposit. The Pitangui deposit represents an important Orogenic Au deposit hosted in clastic metasedimentary rocks of the Pitangui greenstone belt, northwestern portion of the Quadrilatero Ferrifero. Detailed drill hole, petrographic observations and in-situ chemical analyses of the hydrothermal alteration zones show that pyrite is the dominant ore mineral in the deposit and two possible origins are suggest including (i) syngenetic pyrite development at the early stages of the greenstone belt evolution and (ii) epigenetic pyrite, which is associated with hydrothermal processes during the Orogenic Au event. Syngenetic pyrite (PyI) has high Co, Bi, Pb, Sb, Te, Se, Ag and Au concentrations. The PyI could represent an important source of metals, a set of trace elements and likely sulfur for the later Orogenic Au mineralization. Epigenetic pyrites (PyII, PyIII and PyIV), conversely, are mainly found in association with hydrothermal minerals and within the mineralized carbonate-quartz-vein. The variations at Co, Ni, Pb, Te, Sn, Se, As, Bi, Sb, Ag, Mo and W in the epigenetic pyrite indicate that the dehydration PGB sequences during orogenesis constitutes the main fluids sources. The PyV, in turn, only appears at metamafic dyke, but its origin remains unclear.

The Iriri-Xingu domain, located in the central part of the Amazonian craton, consists of extensive occurrences of Paleoproterozoic volcanic rocks and granites with published ages of ca. 1990 to 1840 Ma, which show a strong crustal contribution for their magmas. Exposures of basement rocks are small and rare. Samples from two areas were dated in this work by U-Pb SHRIMP in zircon. In the northern Maribel area, a high-grade pelitic paragneiss presented an age of 2160 ± 8 Ma and the leucosome of a migmatitic orthogneiss, probably a diatexite, crystallized at 2149 ± 20 Ma. These Rhyacian ages suggest that it is part of the Bacaja domain, related to the Trans-Amazonian cycle. The Morro Grande area occurs in the central part of Iriri-Xingu domain, where a high-grade muscovite gneiss with a protolith of 2120-2180 Ma is dated at 1982 ± 7 Ma, and the leucosome of a migmatitic orthogneiss is crystallized at 1979 ± 8 Ma. These are the first records of high-grade metamorphism at ca. 1980 Ma in the Central Brazil shield and may be related to the generation of this Orosirian felsic magmatism, which is widespread throughout the nearby Ventuari-Tapajos province.