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Banded Iron Formations (BIF) developed strongly during the Neoarchean – Paleoproterozoic Eras linked with global environmental processes such as the Great Oxidation Event (GOE) and changes in geodynamics, sea level, geobiology, hydrothermal systems, and sediment deposition conditions. BIF development and distribution worldwide are also related to supercontinent cycles, being a powerful tool to understand the evolution of plate tectonics. In this paper, we used field-based geological-structural data, petrography, X-ray diffraction, and lithogeochemical analyses to perform the first characterization of Banded Iron Formations at the Luis Alves Craton (LAC), Southern Brazil. The LAC BIF are classified as oxide and silicate facies, both with granoblastic texture. Oxide facies consists of quartz and magnetite. Besides these minerals, silicate facies contains olivine and ferrosilite, evidencing granulite metamorphism. Based on major elements oxide facies has a hydrothermal signature, with low content of Al 2 O 3 and TiO 2 , whereas silicate facies register a continental sediment contribution been more enriched in these elements, MgO, MnO, and CaO. Trace-elements also indicate the main source for both silicate and oxide facies, which is seawater with a major influence of low-T hydrothermal sources, besides continental sedimentation sources. The Ce/Ce × anomaly is true negative, representing oxidizing waters, which also may represent a shallow water column depth. The depositional environment is inferred as a shallow, restricted basin. Oxide facies represents sedimentation closer to hydrothermal vents and with weak influence from continental clastic sedimentation, while silicate facies represent sedimentation closer to an adjoining continental landmass. Oxide facies has more Algoma-like characteristics, such as higher Fe and Eu contents, Sm/Yb and Eu/Sm typical of higher hydrothermal fluid inputs, and low siliciclastic contribution. On the other hand, silicate facies resembles Superior-type BIF, with higher siliciclastic contribution, negative Ce/Ce × anomalies, and Eu/Eu* <1.8. In summary, we propose the LAC BIF is representative of a transitional environment from Algoma-to Superior-type. The first depositions of the LAC BIFs may have developed within an Algoma-like environment during the Neoarchean. The waning tectonic and volcanic activity during the Siderian shifted to a platformal environment, with shallower waters that may induce the deposition of carbonates typical of Superior-type deposits. The depositional basin may have been closed by the Rhyacian and those sediments were then pushed down to the lower crust and underwent granulite facies metamorphism. • Oxide and silicate facies BIFs were recognized in the Luis Alves Craton. • These BIFs register granulite metamorphism, having ferrosilite and olivine in their composition. • Through the geochemical data, the depositional paleoenvironment was recognized. • The sedimentary sources of BIFs are both hydrothermal and continental. • These BIFs have characteristics of both Algoma and Superior type deposits. [ABSTRACT FROM AUTHOR]

This paper presents Nd–Hf isotopic data for granitic rocks of both the Matupá (∼1859–1881 Ma) and Teles Pires (∼1790–1793 Ma) intrusive suites located in the south-central region of the Amazonian Craton, central Brazil. The Matupá Intrusive Suite consists of two facies of I-type granites with calc-alkaline affinity emplaced in volcanic arc settings. Facies 1 is composed of syenogranite and monzogranite, and facies 2 is composed of granodiorite. The Teles Pires Intrusive Suite varies from syenogranite to monzogranite with calc-alkaline signature that is consistent with mature magmatic arc settings. The Matupá Intrusive Suite derives from a source with Hf model ages ranging between 2.4–1.91 Ga and εHf (t) between +5.71 and −5.50. Zircon grains in the Matupá Intrusive Suite that are correlatable with the Creporizão Intrusive Suite show Hf model ages of between 2.0 to 2.4, and εHf (t) of −3.76 to + 4.10, while the zircon grains correlatable with the Tropas Intrusive Suite show Hf model ages of 2.1 to 2.4 Ga and εHf(t) of −3.93 to + 2.50. Both facies of the Matupá Intrusive Suite provide εNd (t) values varying from −0.61 to −1.66. The wide range of εHf (t) values (from −5.50 to +5.71) in contrast to the uniformly negative εNd (t) values (from −1.66 to −0.61) of the Matupá Intrusive Suite suggest that Nd–Hf decoupling took place in the magma source during to magma mixing processes. Nd–Hf isotope analyses of the Teles Pires Intrusive Suite reveal a source with Hf model age of between 2.3 and 1.9 Ga. This is indicative of mantle contribution and crustal reworking with values of εHf (t) ranging from +7.17 to −3.3, while other values suggest a more crustal contribution with εNd (t) from −0.07 to −0.71. Crustal contribution in the genesis and magmatic evolution of the Teles Pires Intrusive Suite is also evidenced due to the presence zircon grains inherited from Matupá Intrusive Suite. Zircon inheritance record a distant parental source coeval with the Matupá Intrusive Suite. This paper proposes that the origin and evolution of the Matupá Intrusive Suite is linked to the Cuiú-Cuiú Magmatic Arc while the origin and evolution of the Teles Pires Intrusive Suite is linked to the Juruena Magmatic Arc. Another hypothesis is that both suites were generated and evolved from a single magmatic arc. The Juruena Magmatic Arc is divided into two geographic segments. An eastern segment with a magmatic evolution marked by the interaction of crustal components during the orogenic phase of the Cuiú-Cuiú Magmatic Arc (Tapajós Domain of the Tapajós-Parimá Tectonic Province), and a western segment whose magmatic evolution is marked by rebound of the Juruena Magmatic Arc. • Amazonian Craton. • Teles Pires and Matupá intrusive suites. • Paleoproterozoic granites. • Nd–Hf isotope. • Magmatic arc. [ABSTRACT FROM AUTHOR]

The Southern Brasília Orogen is the result of Ediacaran continental collision between the active margin of the Paranapanema paleocontinent and the passive margin of the São Francisco paleocontinent. The active margin was deformed into the Socorro-Guaxupé Nappe and the associated Embu Domain. This paper presents new U–Pb zircon data and geothermobarometric estimates that allow to reconstruct the metamorphic evolution in these upper plate units. A pre-collisional metamorphism M1 with an age peak in metamorphic rims of zircon grains in the range 680–630 Ma is related to the development of the Socorro-Guaxupé magmatic arc with batholiths dated in a similar time span, 690 - 630 Ma. This metamorphism reached medium pressure granulite facies, now exposed by the tilted uplift and erosion due to the collision. Another peak is detected in metamorphic rims of zircon grains, in the range 630–590 Ma, labeled M2, related to the collision and corresponds to the main metamorphism in the lower plate and accretionary wedge-like nappe stack, underlying the Socorro-Guaxupé Nappe. This nappe stack was affected by greenschist facies metamorphism in the autochthonous underlying craton, grading to high pressure granulite facies in the upper nappe, with local occurrences of retroeclogite lenses. In the Socorro-Guaxupé Nappe and Embu Domain this main metamorphism (M2) is characterized by three metamorphic zones decreasing in grade with distance from the suture: a granulite facies orthopyroxene bearing zone; a high temperature amphibolite facies zone and a lower amphibolite facies zone. Geothermobarometric results in mineral associations related to M2 show temperatures decreasing from about 770 °C to ∼620 °C and pressures decreasing from about 9 kbar close to the suture to about 5 kbar in the southern and western parts of the studied region. On the upper Paranapanema plate, relative to the Socorro-Guaxupé Nappe and Embu Domain units, at the base of the plate, an older metamorphism (M1) is verified with temperatures between 960 and 890 °C and pressures between 11 and 9 kbar, reequilibrated at approximately 700 °C with a pressure of about 9 kbar (M2, continental collision). For this reason, it can be assumed that the rim of the Paranapanema plate was exhumed during the continental collision, since the temperature and pressure of the metamorphic peak determined during the continental collision are lower than those determined for the pre-collisional magmatic arc metamorphism. • Active margin in the Paranapanema Paleocontinent. • Metamorphism related to magmatic arc stage. • Exhumation of the upper plate during the Brasilia Meridional continental collision. • Arc metamorphism superimposed by collisional metamorphism of lesser degree. [ABSTRACT FROM AUTHOR]

The visualization, analysis and interpretation of sedimentary data can be optimized with techniques such as the Digital Outcrop Models (DOMs) generated with the Structure from Motion – Multi-View Stereo (SfM-MVS) technique. In this paper, to demonstrate the usage of DOMs in the characterization of the depositional architecture of a braided fluvial system, we developed a case study in Jaicós Formation, Parnaíba Basin, NE Brazil, where a high-resolution stratigraphic analysis of a braided fluvial system was performed, and the potentials and limitations of the method were evaluated. This multi-scale reservoir analysis allowed the identification, description and interpretation of facies, bounding surfaces and architectural elements. In addition, it was also possible to predict quantitative attributes of the fluvial system that deposited this sequence and evaluate the potential of this formation as a reservoir. • The usage of Virtual Outcrop Models in High Resolution Stratigraphy. • Analysis of facies, bounding surfaces and architectural elements. • Quantitative estimation of the fluvial system that deposited Jaicós Formation. [ABSTRACT FROM AUTHOR]

This paper aims to show the filling and stratigraphy of the units that constitute the Cambambe Basin, that is located at the mid-southern portion of the State of Mato Grosso, Brazil. The rocks of this vulcano-sedimentary unit have been deposited during Upper Cretaceous, between the Santonian and Maastrichtian Stages. The scientific literature has been associated these units to different basins, such as the Paraná Basin, the Parecis Basin and the Bauru Basin and also to other different lithostratigraphic units. Such confusion was the motivation to carry out this study in which the description and interpretation of facies associations was the main tool to clarify some of the aspects related to the Cambambe basin evolution. It has been observed five facies: Polymytic Conglomerate (PCF), Oligomitic Conglomerate (OCF), Siltstone and Mudstone (SMF), Litharenite (LF), Quartzarenite Facies (QF). This facies points to an alluvial fan system, with facies associations interpreted as corresponding to three portions: proximal, immature plains and mature plains. Such facies associations corresponds to the lithostratigrphic units that constitutes the Cambambe basin: the lower portion is the Ribeirão Boiadeiro Group, consisting of the interfingering Quilombinho and Cachoeira do Bom Jardim formations and the upper portion is the Cambambe Formation. An erosive unconfomity separates both portions. The sedimentary record exceeds 400 m in thickness and demonstrates a long-term deposition marked by numerous non-deposition surfaces, including paleosols. • Contributes to the understanding of Cretaceous stratigraphy. • Presents a proposal for the evolution of the Cambambe Basin. • Displays the distribution of facies by lithostratigraphic units. • Interprets four paleoenvironments for Cambambe Basin. [ABSTRACT FROM AUTHOR]

The Passos Nappe is an important tectonic unit of the Southern Brasília Orogen with inverted metamorphism, grading from greenschist facies at the base to granulite facies in the upper part. In the central part, of amphibolite facies, mica schist layers contain garnet megaporphyroblasts (3–9 cm diameter) that contrast with the common-size garnet (0.2–1.5 cm diameter) present in other mica schist layers above and below. This paper intends to describe this textural feature in detail and to discuss its genesis. The megaporphyroblasts are ellipsoidal, with major axis parallel to the mineral and stretching lineation, associated with the main foliation (S 2). Inclusion trails analysis in forty-six megaporphyroblasts, demonstrate straight internal foliation (S i = S 1) in the core, progressively crenulated towards the rim by D 2. S i is discontinuous with the external foliation (S e = S 2), which wraps around the megaporphyroblasts, indicating early syn-D 2 growth. The angle between the axial planes of the included crenulations and S 2 in the matrix indicates that the D 2 deformation continued after porphyroblast growth. Asymmetric deformation shadows reveal non-coaxial D 2 deformation, associated with the emplacement of the nappe (top-to-the SE). The megaporphyroblasts are almandine-rich (73–82%) and spessartine-poor (0.1–2.5%) exhibiting prograde growth zonation. The common-size garnet porphyroblasts of the adjacent micaschists show similar inclusion patterns and chemical zonation indicating a similar tectonometamorphic evolution. A possible origin of the megaporphyroblasts by introduction of fluids along shear zones is discarded because the megaporphyroblasts are distributed along S 0 //S 1 planes that make an angle with S 2. Since the porphyroblasts grew early syn-D 2 , these shear zones should be parallel to S 2 which does not match the observations. The chemical data indicate that megaporphyroblast formation is related to a high-Al protolith composition, associated with scarce nucleation sites. • A first description of garnet megaporphyroblasts from the Passos Nappe. • Developed in the context of a greenschist to granulite inverse metamorphic gradient. • The main control for the large crystal growth was the low garnet nucleation density. • Megaporphyroblasts and common-size garnets share the same tectono-thermal evolution. • Megaporphyroblasts growth-rate was 20 times greater than common-size garnets. [ABSTRACT FROM AUTHOR]

This paper describes facies relationships and stratigraphic architecture of early Permian deglacial deepwater to fluvio-deltaic deposits exposed in the eastern border of the Paraná Basin, southern Brazil. The studied succession is located in the Rio do Sul depocenter and comprises an upward transition between the topmost interval of the Itararé Group (Rio do Sul Formation) and the lowermost unit of the Rio Bonito Formation (Triunfo Member). Geological mapping and facies analysis allowed the recognition of the following facies associations, vertically stacked: thin and thick-bedded turbidites, hyperconcentrated and concentrated density-flow deposits (hyperpycnites), mass-transport deposits, fine-grained heterolithic beds of prodelta, delta-front, shoreface and delta-plain deposits, as well as fluvial beds resting on incised valleys. The stratigraphic analysis through the interpretation of the facies associations, stacking pattern and paleocurrent dispersal trends were enough to define the clinoform stratigraphic architecture, composing a progradational-aggradational pattern. The paleoflows for all facies associations show a main trend towards the south-southwest. In this context, hyperpycnal beds can represent a glacial source from the northeast, because of striated and faceted clasts immersed in the conglomeratic facies, whereas turbidites have been understood as the products of their dilution. Likewise, mass-transport deposits are related to the collapse of the shelf-margin delta, represented by allochthonous blocks composed of deltaic beds within the mass-flow diamictites. Thus, these mass-transport deposits do not evolve downslope to turbidity currents. This configuration was likely for building the relief of the slope system, probably a shelf-edge delta susceptible to mass failure. Paleo-ice flows towards SW recorded in the Rio do Sul Formation, genetic related to fluvio-deltaic deposits of Rio Bonito Formation, highlight the scenario of final stages of the Late Paleozoic Ice Age in the SW of Gondwana and support the previous researches which point to the presence of diachronous ice-spreading centers from paleohighs. • Evidence of glacial source to the northeast is recorded in the LPIA in Brazil. • Clinoform stratigraphic architecture is reconstructed from disconnected outcrops. • Slope clinoform progradation is a possible basin-fill mechanism during deglaciation. • Meltwater discharge is a probable triggering factor for the development of mass-transport deposits. • Mass-transport deposits are related to shelf-margin deltas susceptible to mass-failure. [ABSTRACT FROM AUTHOR]