Teses em Geologia e Geoquímica (Doutorado) - PPGG/IG
URI Permanente para esta coleçãohttps://repositorio.ufpa.br/handle/2011/6341
O Doutorado Acadêmico pertence ao Programa de Pós-Graduação em Geologia e Geoquímica (PPGG) do Instituto de Geociências (IG) da Universidade Federal do Pará (UFPA).
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Tese Acesso aberto (Open Access) Braquiópodes devonianos da Bacia do Amazonas: novos dados taxonômicos, paleobiográficos e relações com as mudanças ambientais(Universidade Federal do Pará, 2024-10-01) CORRÊA, Luiz Felipe Aquino; RAMOS, Maria Inês Feijó; http://lattes.cnpq.br/4546620118003936; https://orcid.org/0000-0003-0276-0575The Devonian marked a significant phase in the evolutionary history of the Brachiopoda. During this period, the Phylum achieved its peak diversity (Emsian) and suffered one of its most significant declines (Frasnian–Famennian), ranking second only to the mass extinction event Permo-Triassic. Among the Brazilian sedimentary basins, the Amazonas Basin has the greater diversity of Devonian brachiopod genera, distributed among the following formations: Manacapuru (Lochkovian), Maecuru (early Eifelian), Ererê (Late Eifelian), and Barreirinha (early Frasnian). Studies of Devonian brachiopods from the Amazonas Basin began in the late 19th century with identifications of material collected during the Morgan Expeditions (1870–1871) and the Imperial Geological Commission of Brazil (1876). These expeditions focused primarily on the Maecuru and Ererê formations. The brachiopod fauna of the Manacapuru Formation (Lochkovian) was unknown until 2015, when during paleontological salvage at the Belo Monte hydroelectric plant in Vitória do Xingu, Pará, Brazil, a significant number of Rhynchonelliformes and Linguliformes samples were recovered. This work aims to carry out the taxonomic identification of brachiopods from the Manacapuru Formation, in addition to analyzing and discussing the possible factors that influenced the diversity of brachiopod genera among the sedimentary units of the Amazonas Basin (Mancapuru, Maecuru, Ererê, and Barreirinha formations). The taxonomic study of brachiopods from the upper part of the Manacapuru Formation (Lochkovian) has allowed, to date, the identification of two genera, Orbiculoidea d'Órbigny, 1847 and Schellwienella Thomas, 1910. Among the materials, Orbiculoidea has the greater diversity, totaling five species: Orbiculoidea baini Sharpe, 1856, Orbiculoidea bodenbenderi Clarke, 1913 and Orbiculoidea excentrica Lange, 1943 in addition to two new species: Orbiculoidea xinguensis Corrêa & Ramos, 2021 and Orbiculoidea katzeri Corrêa & Ramos, 2021. The species O. baini, O. bodenbenderi, and O. excentrica were recorded for the first time in the Manacapuru Formation and Northern Brazil, and they are also the oldest records (Lochkovian) from South America. The presence of Orbiculoidea in the region can be explained by two reasons: the proximity of the Amazonas Basin, located in the northwest of Gondwana during the Lower Devonian, with the paleocontinent Laurussia (where most occurrences of Orbiculoidea are recorded during the Silurian), favored the specific exchange between these two geographic regions; and the global rise in sea level during this period, which flooded much of northwest Gondwana, resulting in the presence of shallow seas in the Amazonas Basin, represented by marine sediments in the upper part of the Manacapuru Formation. These conditions favored the colonization of inarticulate brachiopods during the Early Devonian in northern Brazil. Furthermore, the new species Schellwienella amazonensis Corrêa et al. 2024, of the Pulsiidae Family Cooper and Grant, 1974, is proposed, this being the first record of the genus in the Amazonas Basin. Schellwienella amazonensis n. sp. and Schellwienella marcidula Amsden, 1958 from the Bois d’Arc Formation (Lochkovian), USA, are the oldest records of the genus. In the Devonian, Schellwienella occurred in all stages (Lochkovian, Pragian, Emsian, Eifelian, Givetian, Frasnian, and Famennian), mainly in the marine siliciclastic environments of Gondwana, transiting between temperate and polar latitudes. In the Carboniferous, its stratigraphic distribution was restricted to the Tournaisian-Visean interval, with a preference for warm water environments and carbonate platforms typical of low latitudes. We identified three distinct stages when analyzing the variation in Devonian brachiopod diversity in the Amazonas Basin. In stage 1, the peak of brachiopod diversity occurred in the early Eifelian (Maecuru Formation), when the Amazonas Basin was between subtropical latitudes 30°S and 60°S, under shallow and cold marine conditions, justified by the absence of carbonates, evaporites, and reefs in the region. In stage 2, the first decline in diversity occurred, recorded in the Ererê Formation (late Eifelian), attributed to a warmer climate and deeper waters than in the Maecuru Formation. Stage 3 occurred during the Frasnian when there was a second decline in brachiopod diversity in the Amazonas Basin (Barreirinha Formation). A major global transgression happened at the end of the Devonian. During this period, the Amazonas Basin experienced the deepest marine conditions in its history. Brachiopods of the Barreirinha Formation occur in black shale layers (offshore), attributed to a dysoxic to the anoxic environment of high stress, which explains the low diversity of brachiopods in this unit.Tese Acesso aberto (Open Access) Petrografia e evolução crustal da porção sul do Domínio Pacajá, Cráton Amazônico: evolução policíclica do Mesoarqueano ao Riaciano(Universidade Federal do Pará, 2025-08-13) NERI, Arthur Santos da Silva; DALL’ AGNOL, Roberto; http://lattes.cnpq.br/2158196443144675The integration of field, petrographic, mineralogical, geochemical, geochronological (U-Pb in zircon, monazite, and titanite), and isotopic data (Sm-Nd in whole rock and Lu-Hf in zircon) undertaken in the southern portion of the Bacajá Domain enabled the identification and characterization of new granitoid and charnockitic units previously encompassed within the Cajazeiras Complex. These discoveries allowed a redefinition of the regional stratigraphy and advancing the understanding of the crystallization conditions, origin, and evolution of magmatic and metamorphic orthoderived rocks. A long-lived Rhyacian magmatic event (~70 Ma) was recognized, beginning around 2.12 Ga and lasting until 2.05 Ga. During this interval, the following units were identified: Bandeirante (2.12 Ga, εHf(t) = -6.5 to -4.6, εNd(t) = -3.40); and Alto Rio Preto (2.10-2.06 Ga, εHf(t) = -10.2 to -6.3, εNd(t) = -8.96 -2.80) granites; Maravilha (2.09 Ga, εHf(t) = - 9.2 to -8.2, εNd(t) = -3.01 to -1.91) and Serra Azul (2.07 Ga, εHf(t) = -8.8 to -5.8, εNd(t) = -6.44 to -4.71) charnockites; Bernardino granite (2.05 Ga, εNd(t) = -6.71). Geochemically, the units are mostly high-K calc-alkaline and magnesian (Alto Rio Preto and Bernardino granites, Serra Azul charnockite), transitioning to calcic or alkali-calcic and ferroan (Bandeirante granite and Maravilha charnockite, respectively). They range from metaluminous to weakly peraluminous, except the Bernardino granite, which is strongly peraluminous. The Nd-Hf isotopic integration indicates a crustal source with strongly negative epsilon values and Archean model ages, with a marked contrast to crystallization ages, pointing to long crustal residence times. These granitoids were generated by the collision between the Bacajá and Carajás domains in a late- to post-collisional setting during the Transamazonian Orogeny. Crustal thickening and subsequent delamination are interpreted as the main mechanisms responsible for partial melting and generation of these magmas. The Nd-Hf isotopic signatures reveal a coherent crustal compartmentalization between the Bacajá, Carecuru and Lourenço (Amazonian Craton) and Bauolé-Mossi domains (West Africa Craton), suggesting that these segments were juxtaposed during the amalgamation of the Columbia supercontinent. The Alto Rio Preto granite is composed of epidote-bearing granites and granodiorites-tonalites. This granite was emplaced at pressures of 0.4-0.7 GPa and temperatures between 949 and ~640 ºC, evolved under oxidizing conditions (NNO±0.5 to ±1), with initial water contents of ~2-6 wt%. The preservation of magmatic epidote results of a complex interaction between generation and emplacement pressures, oxidizing conditions and water content in the magma, combined with low density and viscosity that facilitated rapid magma ascent (4-5 km/year) through the crust, preventing complete epidote dissolution. Field and petrographic data suggest that this granite represents a syntectonic intrusion, with geochemical affinities with high-K calc-alkaline series. The parental magma of the monzogranitic facies was derived from dehydration melting of a basaltic source at 0.99 GPa and 865 °C leaving an amphibolite residuum. These granitoids represent an example of crustal reworking of lower mafic crust and do not contribute to net crustal growth in the collisional zone between the Bacajá and Carajás domains. The Maravilha charnockite comprises two petrographic associations: (i) monzonite-granite-charnockite and (ii) granodiorite-monzogranite, with or without igneous orthopyroxene and fayalite + quartz. The (i) association crystallized at temperatures between 1052 and ~680 °C, and evolved under reducing (FMQ±0.5), with ≤3 wt% initial water contents. The (ii) crystallized at temperatures between 918 and ~680 °C and evolved under oxidizing conditions (NNO±0.5), with ~4 wt% initial water contents. Both associations were emplaced at pressures between 0.3 and 0.6 GPa The Serra Azul charnockite consists of tonalites, granodiorites, and rare granites, with or without igneous orthopyroxene. These rocks were emplaced at pressures 0.3-0.6 GPa, temperatures between 1078 and ~700 ºC, and evolved under oxidizing conditions (NNO±0.7 to ±2), with initial water contents ~ 2-3 wt%. Thermodynamic data indicate that fayalite is restricted to low pressures (≤0.3 GPa) and reduced conditions (FMQ -2 to -0.6), but it can crystallize under water-rich conditions (2.3 to 6.2 wt%, possibly up to 9 wt%). In contrast, orthopyroxene can crystallize over a wide pressures range (0.1-1 GPa), from reduced to oxidizing conditions (FMQ-2 to NNO+2.5), and under moderate water contents (~5.2 to 6.5 wt%). The Cajazeiras Complex comprises tonalitic to monzogranitic orthogneisses crystallized at 2.97-2.94 Ga, followed by Pb-loss/metamorphism at 2.80–2.81 Ga and Paleoproterozoic metamorphism 2.21-2.01 Ga. These rocks show geochemical affinities with sanukitoid s.l., representing the oldest sanukitoid magmatism in the Amazonian Craton and the second oldest worldwide. The Nd-Hf data (εNd(t) +0.65; εHf(t) +0.5 to +2.5) suggest a juvenile contribution and short crustal residence time, with model ages close to the crystallization age. The discovery of these rocks implies that the mantle was already metasomatized in the Mesoarchean and opens possibilities for the presence of other typical Archean rocks in the basement of the domain. These orthogneisses were metamorphosed under upper amphibolite to granulite facies. The metamorphic peak was marked by the assemblage clinopyroxene-amphibole-biotite-quartzmagnetite- ilmenite-melt, under conditions of ~0.52–0.55 GPa/760–790 °C at ~2.21 Ga. Cooling toward the solidus occurred at ~ 2.10-2.08 Ga, and retrograde metamorphism is represented by the amphibole-biotite-quartz-magnetite-ilmenite-H₂O assemblage, developed under ~0.40–0.48 GPa/600–650 °C at ~2.01 Ga.Tese Acesso aberto (Open Access) Morfologia e sedimentação em um estuário de macromaré e plataforma adjacente, margem equatorial brasileira(Universidade Federal do Pará, 2025-06-30) MIRANDA, Artur Gustavo Oliveira de; SOUZA FILHO, Pedro Walfir Martins e; http://lattes.cnpq.br/3282736820907252; https://orcid.org/0000-0003-0252-808XUnderstanding morphosedimentary dynamics in macrotidal estuaries is a challenging task, particularly in large-scale systems where seabed morphology and sediment distribution are poorly constrained. This study presents an unprecedented investigation into the morphological changes and the spatial and seasonal variability of surface sediments in the São Marcos Estuary and its adjacent continental shelf. The objective was to assess multidecadal morphobathymetric evolution (1977–2022) and short-term sedimentary pattern modifications associated with climatic seasonality, characterized by a dry season and a rainy season (2020–2021). The 45-year analysis, based on comparisons of nautical charts, revealed a sediment transport pattern primarily controlled by ebb currents, which governs the evolution of key morphological features. A highly deflected subaqueous delta, developed in a marine environment dominated by macrotidal oceanographic processes, was identified on the inner continental shelf—this configuration deviates markedly from classical models of tidedominated deltas. The estuary exhibited morphological instability in the area seaward of the estuarine funnel—proximal to the São Luís Port Terminal—while the region landward of the funnel, including the lower estuary and the inner continental shelf, displayed relative morphological stability. Sediment budget analyses indicated a clearly negative sediment balance for both environments over the study period. The estuary experienced a net volume increase of 1.1 × 10⁹ m³, equivalent to 2.91 × 10¹² tm⁻³ of eroded sediments, with estimated erosion rates of 6.4 × 10¹⁰ tm⁻³/year and a volumetric erosion rate of 2.4 × 10⁷ m³/year. Similarly, the inner continental shelf recorded a net volume increase of 1 × 10⁹ m³, corresponding to 2.65 × 10¹² tm⁻³ of eroded sediments, with annual rates of 2.2 × 10⁷ m³/year for volume and 5.9 × 10¹² tm⁻³/year for sediment mass. Together, both environments accounted for a total net volume increase of 2.1 × 10⁹ m³, representing a total of 5.56 × 10¹² tm⁻³ of eroded sediments, with combined net erosion rates of 4.6 × 10⁷ m³/year and 1.23 × 10¹¹ tm⁻³/year, respectively. Sediment budget calculations across isobaths showed that the estuary experienced substantial sediment losses down to the -30 m isobath. Below this depth, however, sediment behavior was inverse, indicating sediment retention or accumulation. In contrast, the inner continental shelf exhibited a significant net volume increase up to the -25 m isobath, followed by a depositional regime with attenuated sediment accumulation down to the -45 m isobath. For sedimentary deposit characterization, 284 surface sediment samples were collected during the dry season and 281 during the rainy season. These samples were analyzed and spatially interpolated to quantify the percentages of mud (silt and clay), sand, organic matter, and calcium carbonate in both seasonal periods. Textural classifications of surface sediments were assigned based on the schemes proposed by Wentworth (1922), Shepard (1954), and Larsonneur (as modified by Dias, 1996). During the dry season, estuarine sediments were predominantly composed of fine and medium sand, while the adjacent continental shelf was mainly composed of medium sand. Sand accounted for approximately 70% of all dry season samples. In the rainy season, the estuary maintained a similar sediment distribution, with sand again dominant—fine sand being most abundant, followed by medium sand. The adjacent shelf showed a predominance of fine and medium sand, indicating that climatic seasonality exerted influence primarily over the continental shelf region. The intense tidal activity within the study area is the principal driver of the morphosedimentary dynamics of the São Marcos Estuary and its adjacent continental shelf.Tese Acesso aberto (Open Access) Cristaloquímica de esmectitas dioctaédricas em bentonitas brasileiras(Universidade Federal do Pará, 2025-07-01) VEGA PORRAS, David Enrique; PAZ, Simone Patrícia Aranha da; http://lattes.cnpq.br/5376678084716817; https://orcid.org/0000-0002-5880-7638Bentonites are mineral inputs of great industrial interest due to the physicochemical properties of clay minerals from the smectite group. These properties, resulting from the complex crystal chemistry and small particle size of smectites, include various layer charge, swelling capacity, and cation exchange capacity. In Brazil, the main bentonite deposits are located in the municipality of Boa Vista, Paraíba, which accounts for >70% of the country’s production. However, the progressive depletion of these varieties has motivated the search for new deposits. Among them, the Formosa deposit, in the state of Maranhão, stands out. Although both the Boa Vista and, to a lesser extent, the Formosa bentonites have been extensively studied in their <2 μm or coarser fractions, the crystal chemistry of their smectites has not yet been fully elucidated. This is due not only to the typical chemical and structural complexity of smectites, but also to the difficulty of obtaining pure smectite phases and the interference of accessory minerals. In this context, this thesis presents a detailed study of the crystal chemistry of smectite from the Formosa deposit, comparing it with three commercial varieties from Boa Vista: Bofe, Chocolate, and Verde Lodo. The <2 μm, 0.1-2 μm, and <0.1 μm fractions were analyzed, with the latter being the main focus of the study. The analyses included XRD (Rietveld method), FTIR, TEM-EDS, SEM, XRF, AAS, TG, and Mössbauer spectroscopy. These smectites, previously described as montmorillonites, also exhibit significant tetrahedral layer charge. In fact, the four samples show a tetrahedral charge of approximately 0.15 per half unit cell, sufficient to induce swelling after the Hofmann-Klemen treatment. The octahedral symmetry of all four samples was trans-vacant, influenced by both the Fe content and the tetrahedral charge. The structural and chemical similarities between the Formosa and Boa Vista smectites, along with similar smectite content in the <2 μm and <0.1 μm fractions – as quantified by the Rietveld method – demonstrated that the Formosa deposit is a potential alternative to the Boa Vista bentonites.Tese Acesso aberto (Open Access) Petrogênese da Suíte Igarapé Gelado: implicações para o magmatismo neoarqueano da Província Carajás, Cráton Amazônico(Universidade Federal do Pará, 2025-04-30) MESQUITA, Caio José Soares; DALL’ AGNOL, Roberto; http://lattes.cnpq.br/2158196443144675The Igarapé Gelado suite (IGS) is located near the northern border of the Carajás Province, almost at its boundary with the Bacajá Domain, along the Cinzento lineament, and is intrusive in metavolcanic mafic rocks and banded iron formations. The central-eastern portion of the IGS comprises four rock varieties: tonalite to granodiorite with varying contents of biotite and amphibole, (1) with associated clinopyroxene and/or orthopyroxene (PBHTnGd) or (2) devoid of pyroxenes (BHTnGd); and monzogranites that exhibit variable biotite and amphibole content and can be (3) moderately (BHMzG) or (4) strongly (RBHMzG) reduced. The PBHTnGd shows ferrosilite and/or augite with subordinate hedenbergite. The amphiboles are K-hastingsite and, subordinately, Fe-Tschermakite in monzogranites. Biotites are ferroan, and in reduced granites show #Fe > 0.90. These micas are similar to those of alkaline to subalkaline rocks and compositionally akin of primary magmatic biotites. Plagioclase is oligoclase. The integration of thermineral chemistry;mobarometry results and thermodynamic modeling and their comparison with the paragenesis present in natural rocks improved the estimation of crystallization parameters (T, P, ƒO2, H2O), and allowed a better interpretation of magmatic evolution. The IGS granites crystallized at pressures of 550 ± 100 MPa, higher than those attributed to other Neoarchean granites in Carajás provinve. The estimated liquidus temperature for the IGS pyroxene variety is ~1000±50°C. BHTnGd and BHMzG formed within a similar temperature range to PBHTnGd, while RBHMzG had lower liquidus temperatures (≤900°C). Solidus temperatures of around ~660 °C were estimated for the four IGS varieties. The BHMzG magma evolved under conditions of low ƒO2, slightly above or below the FMQ buffer (FMQ±0.5), like those of the Planalto suite and the reduced granites of the Vila Jussara and Vila União suites of Carajás province. In the magmas of the PBHTnGd and BHTnGd varieties the oxygen fugacity attained FMQ+0.5. The RBHMzG crystallized under strongly reduced conditions equivalent to FMQ-0.5 to FMQ-1. The magmas of the monzogranitic varieties evolved with a H2O content of ≥4 wt%, attaining 7 wt% in the case of the reduced monzogranites. This is comparable to, or slightly exceeding, the levels typically attributed to the Neoarchean granites of Carajás province (≥ 4% wt%). In contrast, the variety with pyroxene has a water content (~4 wt%) like that of Café enderbite and Rio Seco charnockite from Carajás province, and Matok Pluton from Limpopo belt. Based on the chemical composition, the rocks from IGS are ferroan, reduced to oxidized A-type-like granites, akin to other Neoarchean granite suites from the Carajás province. The IGS are younger than the 2.76-2.73 Ga Neoarchean granites from the Carajás province. A crystallization concordia age of ~2.68 Ga was obtained by U-Pb SHRIMP in zircon for the RBHMzG variety, and similar upper intercept ages were furnished by the other IGS varieties, except for ages of ~2.5 Ga that resemble the ages of the IOCG Salobo deposits associated with reactivation of the Cinzento Lineament. Tmineral chemistry;he deformation of the IGS rocks was influenced by shear zones linked to that lineament, forming elongated bodies with varied foliation. These zones facilitated the migration and deformation of magmas from the final crystallization stages until their complete cooling, characterizing a syntectonic process. This syntectonicity is associated with the inversion of the Carajás Basin, and the younger crystallization age of these rocks indicates that the inversion occurred up to 2.68 Ga, extending the previously estimated interval (2.76– 2.73 Ga). The IGS displays negative to slightly positive values of εNd(t)(-2.86 to 0.18) and εHf(t)(-3.3 to 0.1), and Paleoarchean to Mesoarchean TDM ages [Nd-TDM(2.98-2.84) and Hf-TDM C (3.27-3.12)]. The positive values of εNd(t) and εHf(t) for the RBHMzG variety, suggest possible juvenile contribution or contamination in the source of its magma. The IGS rocks come from the melting of 19% (PBHTnGd) or 14% (BHTnGd) of contaminated mafic granulite, - and from melting of 9% (BHMzG) and 7% (RBHMzG) of a tholeiitic mafic granulite. The area of occurrence of the IGS is marked by hydrothermalism and mineralizations that locally modified the composition of rocks and minerals, allowing the leaching of REE and Y that changed the composition of some samples of BHMzG approaching them of (false) A1- subtype granites. In addition, these processes were responsible for zircon alteration, which resulted in grains showing enrichment of U, Th, and LREE, and massive textures, that furnished upper intercept U-Pb ages, contrarily to the zircon crystals of the RBHMzG variety that preserved primary characteristics and presented Concordia ages.Tese Acesso aberto (Open Access) Evolução tectono-metamórfica e petrogênese de gnaisses migmatíticos e granitoides mesoarqueanos do Subdomínio Sapucaia (Província Carajás): uma abordagem geocronólogica, isotópica e estrutural(Universidade Federal do Pará, 2025-05-09) NASCIMENTO, Aline Costa do; OLIVEIRA, Davis Carvalho de; http://lattes.cnpq.br/0294264745783506; https://orcid.org/0000-0001-7976-0472The Sapucaia Subdomain, located between the Rio Maria Domain and the Canaã dos Carajás Subdomain, exhibits a Mesoarchean lithostratigraphy that includes greenstone belts, TTG suites, migmatized gneisses, sanukitoids, potassic granites, and "hybrids." This study presents a description of the main migmatitic structures of the basement within this subdomain and proposes the individualization of the Caracol, Colorado, Água Azul and São Carlos orthogneisses, grouping them into the Caracol Gneiss-Migmatitic Complex. Intruding this complex and the Sapucaia greenstone belt sequence, the Água Fria Trondhjemite represents a second generation of sodic magmatism, along with the Mg-rich granodiorites of the Água Limpa Sanukitoid Suite and the Xinguara Potassic Granite. The migmatites exhibit features indicative of in situ and in-source syn-anatectic melting, characterized by stromatic metatexites, net-structured metatexites, schollen, schlieren diatexites, and rare occurrences of patch metatexites. The paleosome is composed of orthogneiss and amphibolite, while the leucosome is quartz-feldspathic and the melanosome is biotite-rich. The unsegregated neosome is represented by a fine-grained granodiorite. Anatexis occurred under upper amphibolite-facies conditions (~650–700°C). The orthogneisses of the Caracol Complex are metagranitoids with high SiO2 and Na2O contents, low MgO, and strong REE fractionation. The sanukitoids of the Água Limpa Suite follow a calc-alkaline trend, enriched in Mg, Ni, Cr, and LILEs. Despite being younger, the Água Fria Trondhjemite exhibits geochemical affinity with the gneisses but with higher K2O content. The Xinguara Granite is calc-alkaline, rich in SiO2 and K2O, with pronounced negative Eu anomalies, indicating a crustal origin. Geochronological data indicate protolith crystallization of the gneisses between 2.95–2.93 Ga, with regional metamorphism between 2.89–2.84 Ga, coeval with the granulites of the Carajás Province. The sanukitoids of the Água Limpa Suite and the Água Fria Trondhjemite date to 2.87 Ga, followed by the Xinguara Granite at 2.86 Ga. Isotopic data from the orthogneisses reveal positive ƐHf(t) and ƐNd(t) values (+0.65 to +3.9), with Hf-TDM C and Nd-TDM model ages between 3.21 to 2.98 Ga, suggesting a juvenile source. The sanukitoids show ƐHf(t) and ƐNd(t) values ranging from –3.31 to +1.76, model ages from 3.28 to 2.91 Ga, δ18O values between 5.0 and 7.6‰, and feldspar Pb compositions with μ > 10, indicating a mantle source contaminated by crustal material. The Água Fria Trondhjemite exhibits ƐHf(t) and ƐNd(t) values ranging from +1.14 to +3.59, with Hf-TDM C model ages of 3.05 to 3.21 Ga. The Xinguara Granite has a Nd-TDM model age of 2.94 to 2.86 Ga, with ƐNd(t) values between +1.32 and +2.55. The temporal proximity between mantle extraction and the crystallization age of these granitoids suggests a rapid crustal growth process in the region. Geochemical data indicate that the melt responsible for the high (La/Yb)N ratio gneiss group derived from the melting of non-enriched metabasalts, previously transformed into garnet-amphibolite. Sources compositionally similar to the average Archean metabasalts from the Sapucaia and Identidade Greenstone Belts could generate such melts, though at different degrees of partial melting (25–30% or 10–15%). The low (La/Yb)N ratio gneiss-forming melt could also be derived from a similar source but without garnet. The sanukitoid melt resulted from 19–20% partial melting of a mantle source enriched by 32% of a TTG-like melt within the garnet stability field. The Água Fria Trondhjemite formed from 5–10% partial melting of metabasalts, whereas the Xinguara Granite resulted from different degrees of melting of sources similar to the older gneisses. Experimental petrology suggests that the sanukitoids crystallized at 1000–970°C in the liquidus stage and 700°C in the solidus stage, with crystallization pressures of 900–600 MPa and emplacement pressures of 200–100 MPa. These rocks exhibit mineralogy indicative of crystallization under oxidizing conditions (NNO +0.3 to +2.5) and high-water content (H₂Omelt > 6–7%). The Mesoarchean evolution of the Sapucaia Subdomain occurred in three main phases: (1) >3.0 Ga, formation of the primitive felsic crust; (2) between 2.95–2.92 Ga, formation of the Caracol Complex gneisses; (3) 2.89–2.84 Ga, crustal thickening during sinistral transpressive tectonic associated with exhumation and metamorphism of the TTG basement. Crustal stabilization allowed for the formation of younger sanukitoid and TTG magmas (Água Fria Trondhjemite). The ascent of these magmas supplied heat for the melting of regional basement metagranitoids, leading to the formation of anatectic granites. During this stage, gneissic foliation was obliterated by deformation and intrusion of younger granitoids. The integration of the data suggests that tectonic processes facilitated the generation of both crustal and mantle-derived magmas at the end of the Mesoarchean in the Sapucaia Subdomain. It can be inferred that crustal growth in the Sapucaia Subdomain was initially controlled by mantle plumes associated with vertical tectonics, similar to observations in the Pilbara and Dharwar cratons. However, unlike the Rio Maria Domain, the dome-like structuring of the gneissic basement in this subdomain was intensely obliterated by the action of sinistral transpressive tectonics (non-coaxial deformation), forming sigmoidal bodies with an E-W orientation.Tese Acesso aberto (Open Access) Petrogênese dos granitos Manda Saia e Marajoara: contribuições para a definição da natureza do magmatismo paleoproterozóico da Província Carajás.(Universidade Federal do Pará, 2024-12-13) SANTOS, Rodrigo Fabiano Silva; OLIVEIRA, Davis Carvalho de; http://lattes.cnpq.br/0294264745783506; https://orcid.org/0000-0001-7976-0472The Marajoara (MJG) and Manda Saia (MSG) granites are located in southeastern Pará State, Brazil, and represent circular intrusions with stock dimensions embedded in Mesoarchean rocks of the Rio Maria Domain, in the central-southern portion of the Carajás Province. These rocks outcrop as extensive pavements, exhibiting no solid-state deformation features (isotropic aspect) and frequently containing angular enclaves of the surrounding host rocks. The MJG comprises equigranular biotite monzogranite (eBMzG) and heterogranular (hBMzG) varieties, as well as porphyritic (pME) and microgranular enclaves (ME) restricted to the hBMzG facies. Quartz content and plagioclase/microcline ratios vary significantly, allowing these rocks to be classified from syenogranitic to monzogranitic, and even granodioritic in the case of microgranular enclaves. They are peraluminous granites, similar to ferroan granites with high K2O+Na2O/CaO and FeOt/(FeOt+MgO) ratios, enriched in Rb, Zr, Y, Nb, F, and heavy REEs, with more evolved facies displaying low Sr and Ba contents. In REE patterns, negative Eu anomalies are prominent, and heavy REEs show a gradual increase with magmatic differentiation. These granites fall within the intraplate granite field and exhibit geochemical affinities with A-type granites. Their FeOt/(FeOt+MgO) ratios align with typical oxidized (hBMzG and pME) and reduced (eBMzG) A-type granites, while the MSG displays a moderately reduced character. The ME, however, show affinity with magnesian and calcalkaline series granites. According to biotite mineral chemistry, MSG and the hBMzG facies of MJG fall within the magnetite series field, while eBMzG rocks are similar to ilmenite series rocks. SHRIMP zircon U–Pb analyses provide crystallization ages of 1884 ± 11 Ma for MJG and 1866 ± 10 Ma for MSG (LA–SF–ICP–MS). Lu–Hf isotopic data indicate ƐHf(t) between - 11 and -18 and Hf-TDMC from 3.2 to 3.6 Ga for MJG; and ƐHf(t) between -13 and -19 and Hf-TDMC from 3.3 to 3.6 Ga for MSG. The compositional gaps among the various MJG varieties suggest that their magmas are not cogenetic. Geochemical modeling suggests that MJG and MSG were generated by partial melting of tonalitic rocks, with occasional metasedimentary contributions, at a melting rate ranging from 16 to 18%, with a residual assemblage of plagioclase, quartz, biotite, magnetite, and ilmenite. Felsic and mafic magma mixing played an important role in the emplacement. The enclaves represent enriched lithospheric mantle-derived magmatism injected into the magma chamber during the subduction process, interacting to varying degrees with the magma forming the Marajoara granite. This hypothesis may be reinforced by the occurrence of a 1.88 Ga diabase-porphyritic granite composite dyke in the Rio Maria region. The proposed model suggests that the granitic magma initially formed a magma chamber, followed by repeated mafic magma injections, resulting in small-scale convection. Subsequently, large volumes of hot mafic magma entered the chamber, leading to mixing processes. Microgranular and porphyritic enclaves were formed due to magma mixing in areas where there were temperature contrasts between felsic and mafic magmas. The results presented in this study highlight the importance of the Archean crust in the origin of Paleoproterozoic granites, which were emplaced in shallow crustal levels through a dyke feeder system as a result of extensional tectonics.Tese Acesso aberto (Open Access) Transformação de rejeitos de lavagem de bauxita em hidróxidos duplos lamelares e óxidos mistos para aplicações e remediação ambiental.(Universidade Federal do Pará, 2024-08-05) NASCIMENTO, Renata de Sousa; FIGUEIRA, Bruno Apolo Miranda; http://lattes.cnpq.br/6852513231905237; https://orcid.org/0000-0002-0507-8662; CORRÊA, José Augusto Martins; http://lattes.cnpq.br/6527800269860568In the present thesis, bauxite washing wast were explored as a low-cost precursor for the preparation of a layered double hydroxide (LDH) nanoadsorbent similar to pyroaurite (Mg-Fe-Al-NO3). Subsequently, this LDH precursor was calcined to obtain the so-called mixed metal oxides (MMO) and encoded as CLDH-X, where X represents the calcination temperature. The LDH was synthesized by the classical co-precipitation method from a solution rich in trivalent cations Fe3+ and Al3+ obtained after acid digestion of the bauxite wash tailings. The synthetic materials HDL and CLDH-X were characterized structurally and morphologically by X-ray diffraction (XRD), infrared spectroscopy (FTIR) and Raman, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and specific surface area measurements (BET method). The first material was tested for the removal of erythrosine B (EB) from aqueous solutions, while the second was applied for the adsorption of ponceau 4R (P4R). Effect of temperature, adsorbent dosage, pH, contact time, and initial concentration were investigated. LDH has proven to be suitable for rapid and efficient removal of EB. In fact, almost complete adsorption of the dye onto the nanostructured pyroaurite occurred within the first 20 min leading to an adsorption capacity (qe) equal to 94.25 mg/g for a specific surface area of 81 m2/g. Its dye removal rate (percentage) increased from 89% to 93% as the temperature increased from 308 K to 328 K. Parallel to the adsorption experiments, using CLDH-X, the so-called memory effect suffered by these mixed oxides was investigated and how this structural regeneration directly affects the removal of P4R. Both CLDH-X showed excellent performance in P4R adsorption, CLDH-400 achieved a removal rate of 99% in just 30 min of contact time, while CLDH-600 achieved a removal rate of 98% in 240 min. This contact time was drastically reduced when the dye solution was heated to 313 K, in just 60 min the removal rate reached 99.5%. It could be inferred that the excellent adsorption capacity of CLDH-400 was mainly influenced by the memory effect. On the other hand, this same phenomenon negatively interfered in the adsorption experiments, causing the removal efficiency to drop by approximately 40%. The results suggest that both HDL and mixed metal oxides are promising adsorbents and useful materials in the treatment of water contaminated by synthetic dyes.Tese Acesso aberto (Open Access) A capa carbonática marinoana do Sul do Cráton Amazônico: multiproxies aplicados na reconstituição paleoceanográfica e geobiológica do início do Ediacarano.(Universidade Federal do Pará, 2024-08-30) SANTOS, Renan Fernandes dos; SANSJOFRE, Pierre; NOGUEIRA, Afonso César Rodrigues; http://lattes.cnpq.br/8867836268820998The post-Marinoan glaciation (~650-635 Ma) was the most severe event from the late Cryogenian period of the planet. The snowball Earth conditions induced a climate anomaly, triggering major changes in the paleoenvironmental and ocean chemistry recorded in the carbonate cap sequences. The dramatic effects on the global sea level were caused by glacial-isostatic adjustment (GIA) and ice gravity on the coastal zones associated with the ocean thermal expansion under greenhouse conditions. The fast input of meltwaters contributed to a stable density ocean stratification formed by hypersaline deep waters and meltwater surface layers. The ocean destratification occurred in a timescale ranging from tens of thousands to thousands of years. The Puga cap carbonate (~635 Ma), the basal deposits of the Araras-Alto Paraguai basin from the southern Amazon Craton, is revisited in the classical sections from the Tangará da Serra and Mirassol d'Oeste, Mato Grosso State. This succession is one of the best records for evaluating the supersaturation events under GIA and transgression conditions that controlled the accommodation space in the southern Amazon Craton. Sedimentological and stratigraphic data were integrated with new paleoceanographic, and paleo-redox data combined with diagenetic, crystallographic, geochemical (primarily rare earth elements and trace metals), and isotopic (whole rock 87Sr/86Sr, εNd(t), δ 13C, δ 18 O, Sm/Nd) results providing further insights to understand the post-Marinoan conditions. The Puga cap carbonate sequence spans approximately 90 meters, with the first 10 meters composed of glaciomarine deposits, diamictites, and dropstones from the Puga Formation. The basal contact with diamictites is plastically deformed, indicating rapid carbonate precipitation. The cap dolostone consists of stratiform doloboundstones with gypsum pseudomorphs and domal doloboundstones with tubestone, which were deposited in a shallow platform with intense microbial activity. Peloidal dolomudstone/dolopackstone with laminations parallel to bedding planes and peloidal dolograinstones/dolomudstone with quasi-planar laminations and low-angle truncation were formed in a wave-influenced shallow platform. The cap limestone conformably overlies the cap dolostone deposits, marked by dolomitic marlstone with calcite crystal fans (aragonite pseudomorphs) interbedded with mega-rippled limestone. The facies association of the cap limestone indicates moderately deep-water conditions dominated by waves and storms transitioning to a deep platform supersaturated with CaCO3. The main diagenetic process is dolomitization during syn-depositional and shallow burial stages. Rare earth element + yttrium patterns have been analyzed in these deposits. Low Y/Ho ratios (<36) in the cap dolostone suggest a mixture of meltwater and seawater, while the base records superchondritic Y/Ho values up to 70 and high Eu/Eu* values up to 3, indicating upwelling of hypersaline seawater with hydrothermal fluid interaction, suggesting dolomite precipitation during ocean destratification. The radiogenic isotopic compositions of Nd, combined with other proxies such as δ 13C and 87Sr/86Sr, indicate the influence of continental and marine contributions. The Nd isotopic system, less susceptible to diagenetic exchanges, revealed distinct signatures of water masses and enhanced weathering of the Amazon Craton during deglaciation. This process is indicated by geochemical trends (e.g., Y/Ho) and 87Sr/86Sr, εNd(t), δ 13C values. 87Sr/86Sr data in the cap dolostone range from 0.7264 to 0.7084, higher than pre- and postglacial seawater values. More radiogenic 87Sr/86Sr values associated with less radiogenic εNd(t) values, similar to those found in diamictites, reinforce coastal weathering contribution to meltwaters. This multiproxies approach is a reconciliation with the previous rapid cap carbonate precipitation model following the short-term timescale for ocean destratification. Redox-sensitive trace metal data, U, Mo, V, Ni, Cu, P, and δ13C isotopes, indicated paleo-redox states and paleoproductivity during the post-glacial transgression. The cap dolostone precipitated under oxygenated conditions with extensive microbial community contributions, transitioning to predominantly dysoxic conditions with wave action in the last deposition phase. The abrupt sea-level rise altered the biogeochemical cycle, indicating a direct relationship between oxygen production and rapid microbial community colonization. The rapid sea-level rise and continental weathering reduced seawater Mg/Ca ratios with substantial Ca2+ input, also demonstrated by εNd(t) values, causing the change of dolomitic platform to CaCO3 -supersaturated seas in the Amazon Craton margin. Additionally, low siliciclastic content in the cap dolostone is consistent with the siliciclastic starvation model, and the abrupt increase caused the decline of microbial communities coincident with the predominance of dysoxic conditions and longterm transgression. During specific Cryogenian-Ediacaran deglaciation scenarios, anomalous sedimentary and geochemical processes generated one of the most complex paleoenvironmental disturbances in the biogeochemical cycle. They strongly influenced the rapid primary productivity, directly impacting microbial life. The analysis of Precambrian scenarios in the Amazon Craton unraveling the extreme climates sheds critical light on extremophile life proliferation and has strong implications for understanding other planetary surfaces.Tese Acesso aberto (Open Access) As sucessões cambriana-siluriana da Bacia do Parnaíba e da Província Mineral de Carajás: paleoambiente, proveniência e extensão da glaciação siluriana no Gondwana Oeste.(Universidade Federal do Pará, 2024-01-12) ROMERO BARRERA, Ivan Alfredo; NOGUEIRA, Afonso Cesar Rodrigues; http://lattes.cnpq.br/8867836268820998The Lower Paleozoic sedimentary record corresponding to the northern and northeastern Brazilian sedimentary basins is well exposed in outcrops within the Parnaíba Basin and locally in the Carajás Mineral Province (CMP). These deposits, considered Cambrian/OrdovicianSilurian age, based on the Silurian glacial strata identification maximum depositional age (UPb in detrital zircon), represent a unique opportunity to understand the paleoenvironmental and paleogeographic evolution of Western Gondwana. The records analyzed in this study include siliciclastic sequences with thicknesses ranging between 300–400m and lateral continuity that exceeds 300,000 km², representing alluvial, glacio-marine, and deltaic deposits unconformably overlying crystalline basement rocks. The basal succession comprises coarse-grained lithoarenites and fluvial conglomerates exposed in intracratonic basins and isolated grabens in northeastern Brazil and central Africa. In Brazil, these units correspond to the Ipu, Cariri, and Tacaratu formations, while in Africa, they are represented by the Inkisi, Banalia, and Biano groups. The conglomerates and sandstones of the Ipu Formation, at the base of the Serra Grande Group in the Parnaíba Basin, are here correlated with the corresponding alluvial deposits of the Gorotire Formation in the Paredão Group within isolated grabens in the CMP. These deposits are sharply overlain by massive to stratified diamictites, carbonaceous shales with dumpstone and dropstone structures, and sandstones with sigmoidal cross-stratification belonging to the upper member of the Paredão Group in CMP and the Tianguá Formation in Parnaíba Basin. During the amalgamation of the Gondwana supercontinent in the Neoproterozoic-Cambrian periods transition, the coalescence of continental masses was controlled by the development of major orogenic systems, accompanied by the deposition of the first sedimentary sequences in rift-type basins. These extensive subsiding geotectonic compartments coincided with the reorganization of regional drainage patterns and the generation of large sediment volumes transported by transcontinental fluvial systems. At the Cambrian-Ordovician period boundary, these “Big Rivers” extended across vast peneplains for hundreds of kilometers, overcoming the current intracratonic basin limits along the northwestern margin of the supercontinent and fed by diverse source areas. The fluvial architecture of these successions consists of massive to stratified tabular beds of conglomerates and sandstones, laterally continuous over kilometers and sometimes filling concave-channel geometries. These deposits are arranged in metric-scale fining-upward cycles, reflecting the dominance of sheet flow processes with sporadic channel incisions filled by small- to large-scale two- and three-dimensional bedforms. Alluvial fan facies for the Ipu Formation were not observed, suggesting basinal edges erosion. In addition, unidirectional paleocurrent data predominantly oriented NNW extend beyond the Parnaíba Basin current limits, indicating that the depositional area was more extensive than presently preserved. During the transition between the Ordovician and Silurian periods, the western portion of the Gondwana Supercontinent experienced an extensive glacial period, climaxing in the Hirnantian (~445 Ma), as recorded in rocks from northern African basins. Thus, the glacial event that began in the Middle Ordovician likely froze continental areas representing the headboard of large alluvial systems in Africa and Brazil, initiating the decline of these transcontinental drainages. The migration of the supercontinent toward the South Pole coincided with astronomical factors such as Earth rotational changes and decreased solar radiation, promoting ice sheet growth. The end of the glacial event was marked by the largest eustatic sea-level rise in Earth history, triggering significant marine transgressions starting in the Llandovery (~443 Ma) and ending in the Ludlow (~423 Ma). The melting phase promotes the development of proglacial glacio-marine systems with widespread icebergs, ablation processes, and an expansion of anoxic zones in seas, allowing extensive global organic matter preservation. The ice-melt deltaic systems progradation marks the end of the post-glacial sequence deposition. These events records are well represented in Paredão Group upper member and Tianguá Formation successions. Through the investigation of Ordovician sedimentary records from northeastern Brazil and central Africa, complemented with detailed analyses of fluvial architecture and U-Pb detrital zircon ages, a compelling narrative emerges of immense transcontinental drainage systems that shaped the landscape after the Gondwana Supercontinent amalgamation. Additionally, Paleozoic records are described for the first time in the CMP, providing a critical key for improved stratigraphic understanding and enhancing paleoenvironmental, paleogeographic, and paleoclimatic reconstructions of the Gondwana supercontinent during the Lower Paleozoic.Tese Acesso aberto (Open Access) Quartzo e cassiterita como marcadores da evolução magmático-hidrotermal dos Granitos Mocambo e Velho Guilherme, Província Carajás.(Universidade Federal do Pará, 2024-12-16) BARROS NETO, Rubem Santa Brígida.; LAMARÃO, Claudio Nery; http://lattes.cnpq.br/6973820663339281; https://orcid.org/0000-0002-0672-3977Quartz crystals from the Mocambo and Velho Guilherme Granite and cassiterite from the Mocambo Granite present in greisenized rocks and hydrothermal veins belonging to the Velho Guilherme Intrusive Suite, Xingu region, Amazonian Craton, were analyzed by scanning electron microscopy - cathodoluminescence (SEM-LC) and by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Morphological and textural analyses obtained through CL images allowed the identification of similar types and the definition of an evolution pattern for the quartz present in the rocks of both plutons. The magmatic type (Qz1), present in the least evolved and little altered rocks, passing through Qz2 and Qz3, common in moderately altered rocks, up to types Qz4 and Q5, dominant in the most evolved and hydrothermalized rocks, including the greisenized ones and the associated quartz veins, both markers of the mineralization of cassiterite, wolframite and sulfides present in this suite. Chemical analyses show that all quartz from the Mocambo Granite, which contains an important secondary cassiterite deposit, are more enriched and present greater variability in the elements analyzed. Magmatic quartz is more enriched in Ti and present varying levels of Al, K, P, Na and Fe. The higher contents of Al, K and Li identified in hydrothermal quartz differentiate them from magmatic quartz. In turn, cassiterite crystals show varied textures in cathodoluminescence images, such as concentric/oscillatory and sectoral zoning, as well as banding formed by more and less luminescent bands. Homogeneous dark zones are common and relict crystals, usually present in quartz veins associated with wolframite, are less luminescent. The main trace elements found in cassiterites are represented by Ti, Fe, Nb, Ta, W, Zr, Al and Hf, similar to those of tin mineralizations present in quartz and greisens veins of deposits from different geological environments. However, the pattern formed by the normalized “spidergram” is unique, presenting positive peaks of Sc, Ti, Nb, Sb, Ta and W and negative peaks of V, Mn and Fe.Tese Acesso aberto (Open Access) A aplicação da cromatografia gasosa acoplada (GC-FID), isótopos estáveis, palinologia e razão C:N na reconstituição paleoambiental de manguezais do Estado da Bahia e Espírito Santo.(Universidade Federal do Pará, 2024-07-30) SILVA, Fernando Augusto Borges da; ALBERGARIA-BARBOSA, Ana Cecília Rizzatti de; http://lattes.cnpq.br/2666263256585897; FRANÇA, Marlon Carlos; http://lattes.cnpq.br/8225311897488790; https://orcid.org/0000-0002-3784-7702Mangroves depend on ideal geomorphological, geochemical, and climatic factors to develop. Brazil, with its highly indented coastline under tropical and sub-tropical climate regimes, presents suitable conditions for the establishment of these ecosystems and distribution. The dynamics of these mangroves can be influenced by factors related to climatic variations and changes in hydrodynamic flow, resulting in modifications in sediment input and the origin of organic matter. These changes can be observed throughout the Holocene in different regions in of the country. On the northeast and southeast coast, the evolution of these ecosystems is associated with fluctuations in relative sea level (RSL) and sedimentary dynamics, while in the southern region, the change in the distribution of mangroves is a reflection of fluctuations in the RSL and climate changes caused by warming global. Recent studies seek to describe the evolution of these environments based on the elemental and isotopic characterization of organic matter. These constitute important tools in paleoenvironmental reconstruction. However, it is necessary to remember that the comparative analysis of the largest possible number of independent parameters is relevant as it adds value to the research and increases the reliability of the data to be analyzed, generating more precise information. Therefore, aiming to unravel the dynamics of organic matter in mangrove environments, as well as understanding movements of expansion and/or contraction of these ecosystems, analyzes of nalkanes were carried out using chromatography (GC-FID), associated with the sedimentary study, pollen data, isotopic and elemental analyses, synchronized with 14C and 210Pb dating, which allowed obtaining information about past biogeochemical processes and environmental changes during the Holocene and Anthropocene in the coastal plain at the mouth of the Itapicuru river (BA) and at the mouth of the Barra Seca and Jucu rivers (ES). Thus, the results of this research are presented in five scientific articles. The first, see chapter III, deals with the expansion of mangroves at the mouth of the Itapecuru river (BA) during the Anthropocene. The second scientific article (chapter IV) deals with the dynamics of mangroves at the mouth of the Barra Seca River, on the northern littoral of the State of Espírito Santo. The third article (chapter V) discusses the palynology tool used to understand the dynamics of coastal vegetation.The fourth article (chapter VI) presents the environmental changes that occurred at the mouth of the Jucu River, on the central coast of the State of Espírito Santo. Finally, the fifth article presents the results of n-alkanes analyses, compared with isotopic, elemental, palynological data, and 14C dating on the coastal plain of the Barra Seca River.Tese Acesso aberto (Open Access) O Camp nas bacias dos Solimões, Amazonas, Parnaíba e Parecis, Norte do Brasil: implicações geotectônicas e deposicionais para o jurássico do Gondwana Ocidental.(Universidade Federal do Pará, 2024-08-23) REZENDE, Gabriel Leal; NOGUEIRA, Afonso César Rodrigues; http://lattes.cnpq.br/8867836268820998Geological studies in conjunction with applications of geophysical techniques are being widely used to highlight and characterize CAMP gravimetric anomalies throughout Northern Brazil, including the Solimões, Parecis, Amazonas and Parnaíba basins. Interpretations of a residual gravimetric anomaly from these basins were used to expand the understanding of the distribution of CAMP throughout the subsurface. This study was carried out through qualitative and quantitative interpretations of gravimetric data, supported by surface geological information, mainly stratigraphic data based on outcrops. From direct gravimetric modeling, based on available crustal gravitational structure models to separate a residual gravity signal from observed gravity data, realistically detailed geological and tectonic features were interpreted, providing useful information for a geophysical interpretation of geological sources. With the residual gravity anomaly, a map of the elastic thickness (Te) of the basins was obtained, using a new procedure, presumably allowing some gaps presented in the current literature on the CAMP to be filled. For each Te value, the residual gravimetric signal was calculated, considering the surfaces described by topography and Moho for a regional model with standard density and discretized into prisms. The cross-correlation between the observed gravity signal and calculated gravity signal made it possible to obtain a map of the elastic thickness of the studied areas. The highest correlation value is directly related to the best value of elastic thickness and Moho depth associated with crustal deformation. Our study used a combination of these techniques to presumably define the possible extent of Jurassic magmatism, the basin rheology of igneous body intrusion and history of thermal subsidence that largely controlled depositional control during and after the CAMP. The presence of low gravity values is closely related to the less dense lithological units of the upper crust, while the high gravity values are related to high-density rocks correlated to the continental tholeiitic flood basalts of the CAMP. The use of residual gravity anomaly based on crustal modeling combined with previous geological data was effective in identifying the CAMP record in these Amazonian sedimentary basins. Furthermore, some gravimetric signatures correlate well with the main structural discontinuities, particularly with the Monte Alegre Dome and Xambioá, Serra Formosa and Vilhena arches, respectively, in the Amazon, Parnaíba and Parecis basins. This interpretation provides a reasonable explanation for understanding structural lineaments without exclusively tectonic connotations, assuming a new interpretation for the gravitational field related to intracrustal density contrast or residual gravity field for these basins. Eastern Gondwana was gradually uplifted by subvolcanic bodies of the Penatecaua magmatism in the Amazon and Solimões basins. In contrast, extrusive volcanism characterizes Mosquito magmatism in the Parnaíba basin interspersed with intertrap sediments. Information obtained from the elastic thickness map, Moho depth and residual gravity signal indicate a thinner crust in the Parnaíba basin favoring the magmatic eruption induced by a hot spot installed on the western edge of the basin. On the other hand, in basins with denser and thicker crust, magma accumulates mainly as sills, providing greater resistance to rupture due to the swelling of the CAMP. The Parnaíba Basin experienced three magmatic pulses at intervals of approximately 1 Myr, alternating with the development of aeolian-fluvial-lacustrine systems (intertrap sediments) during non-magmatic periods, indicating short intervals of magmatic resump-tion and cooling in the CAMP, contrasting with the longer and continuous magmatism in the Amazon and Solimões basins, which lack intertrap deposits. These results are important for a new disposition of the tectonomagmatic, structural and stratigraphic history for these basins, since from a new context or geological evolution for the area it will allow a better understanding of the studied basins in lava-sediment interaction, preserved from the Jurassic and related to the CAMP events, which preceded the main continental rupture in northwestern Pangea.Tese Acesso aberto (Open Access) Arcabouço estrutural e geocronologia dos granitóides da região de Várzea Alegre: implicações para a evolução crustal da Província Borborema(Universidade Federal do Pará, 2024-07-25) SOUSA, Luis Kennedy Andrade de; DOMINGOS, Fabio Henrique Garcia; http://lattes.cnpq.br/3975188208099791; https://orcid.org/0000-0002-2447-3465; GALARZA TORO, Marco Antonio; http://lattes.cnpq.br/8979250766799749; https://orcid.org/0000-0002-7271-4737In the Borborema Province, in northeastern Brazil, several granitic batholiths and plutons are found, which are records of subduction and collision episodes related to the Brasiliano Orogeny. Within this large orogenic system, the emplacement mechanisms of many granites are closely related to the development of deep-seated shear zones, one of which is the Patos Shear Zone, which in its western segment is composed of slices of rocks such as granites, gneisses, metapelites, quartzites, and amphibolites that form an imbricated system. In this context, the present work was carried out with the aim of bringing new geochronological and microstructural data to add to the understanding of the nature of the processes that formed and modified the undifferentiated granitoids in the Várzea Alegre region (CE). The granites are classified as Biotite Monzogranite and Garnet Monzogranite, they present phaneritic and porphyritic textures, in some places, their mineralogical composition is mainly composed of plagioclase, K-feldspar, and quartz, in addition to biotite, muscovite, and garnet. The granitoids are composed of elongated bodies concordant with the host rocks. The deformation imposed on the granitic bodies developed ductile structures with NE-SW orientation and kinematic criteria indicate that the deformation occurred predominantly dextral. Microstructural features, observed mainly in rocks near the edges of the granitic bodies, show that quartz crystals exhibit microstructures such as sutured to lobate contacts, undulating extinction, ribbons, and the chessboard pattern, indicative of recrystallization by grain boundary migration (GBM), compatible with temperatures of 500ºC. Biotite crystals that define the mylonitic foliation characterize a spaced foliation that separates microlite domains formed by aggregates of quartz and plagioclase, with asymmetric lenticular geometry in the granites, similar to the foliation impressed on the gneisses of the Granjeiro Complex. Based on EBSD data, the granites exhibit a grain size distribution with a concentration of crystals <100 μm. From the pole figures, the quartz OPC shows that the dominant system was rhombohedral to prismatic, indicating a medium to high deformation temperature, in a context of progressive non-coaxial deformation. However, from the interpretation of the misorientation angle, it is shown that during the deformation history of the granites, these bodies underwent lower temperature deformation. U-Pb geochronological data on zircon provided crystallization ages of 573 to 576 Ma for this granitic magmatism. The Hf-TDM C model ages of these granitoids ranged from 2.84 to 3.30 Ga and the ƐHf(t) values from -21.9 to -29.6 suggesting a strong incorporation of mesoarchean crustal source. Similar Sm-Nd data in whole rock show that these granitoids have Nd-TDM model ages between 2.14 and 3.33 Ga and ƐNd(t) values between -20.02 and -31.79, suggesting a strong contribution from meso paleoarchean and paleoproterozoic crust (orosirian to riacian) to the formation of the granitic magma that originated the granites in the Várzea Alegre region (CE). These granitic bodies are classified as Itaporanga type and sin-transcurrent, as they have similar ages and structural features to other sin-transcurrent granitic bodies in the Borborema Province. These granites were generated from magmatism associated with the change in the predominant deformation in the Borborema Province, which was the result of the final stages of the Brasiliano Orogeny within the context of simple deformation, with the development of large shear zones.Tese Acesso aberto (Open Access) A pluma do rio Amazonas: fonte: dinâmica e transporte de sedimentos para estuários e manguezais do litoral leste amazônico.(Universidade Federal do Pará, 2024-06-14) SILVA, Ariane Maria Marques da; ASP NETO, Nils Edvin; http://lattes.cnpq.br/7113886150130994; https://orcid.org/0000-0002-6468-6158The Southeastern Amazon Coastal Zone (SACZ) includes the largest mangroves belt in the world and more than 20 macrotidal estuaries. In this area, a large volume of fine sediments has been deposited during the Holocene, however, it is known that the local rivers are black water rivers, carrying small amounts of suspended sediment. Therefore, since decades the sources and transport mechanisms of fine sediments to estuaries and mangroves have been speculated and investigated. It was recently demonstrated the existence of an offshore source of muddy sediments to the mangroves. Due to its proximity, the Amazon River has been seen as the probable main source of sediments, where an average flow of 170x103 m3 .s-1 and suspended sediment concentrations in the order of 80 mg.L-1 would represent a nearly inexhaustible source of mud to both estuaries and mangroves. However, the provenance and transport processes by which the mud of the Amazon would reach the SACZ, providing mangrove progradation, are not yet understood, since the plume is mostly drifted to northwest. In this context, the sedimentary constitution of the inner continental shelf and its reworking must also be evaluated, as well as the possibility of mud supply to the east of the study region. The present study aimed to integrate and complement efforts on sediment dynamics in the estuaries (Mocajuba, Caeté and Gurupi) and mangroves of the SACZ, combining studies on the inner continental shelf. Therefore, tools and approaches from hydrodynamics, sedimentology and biogeochemistry were used to identify and understand the sources and transport mechanisms of muddy sediments for the sector, composing a distance gradient from the mouth of the Amazon River, as well as a gradient of the drainage basins size. The Mocajuba estuary presents quite peculiar aspects in terms of morphology and hydrodynamics. The morphology of the estuary is strongly influenced by structural evolution and faults caused by neotectonic events since the Neogene, resulting in deep and straight areas in the lower and middle portions of the estuary. The tide propagates into the estuary without significant deformations, as a result of the combination between inherited morphology and hydrodynamic aspects. Salinity showed higher values during dry seasons, while the concentration of suspended sediment was higher during rainy seasons. Estuarine circulation in Mocajuba is similar to fjord because of the deep, however, without salinity stratification. The estuarine turbidity maxima zone did not occur due to the high depth areas, low current velocities, and low suspended sediments concentration. However, a “high turbidity wedge” was observed near the mouth of the estuary, evidencing the Amazon River plume influence. The Caeté estuary is classified as a coastal plain, tide-dominated, with a semidiurnal regime and considerable variations during the spring and neap phases. From a scientific point of view, this is one of the most studied estuaries in the SACZ, including geology, geomorphology, hydrodynamics, sedimentology, geochemistry, biogeochemistry, ecology in general, among other studies areas. For this Thesis, the Caeté estuary was considered a “model estuary” due to its geographic location (regarding to the Amazon River mouth, Mocajuba and Gurupi estuaries distances), the hydrographic basin size and especially because of the data available in scientific articles that prove the influence of an offshore source of fine sediments. Gurupi is a typical coastal plain estuary, shallow, funnel-shaped, tide-dominated, but partially mixed. Salinity levels and suspended sediment concentrations were higher at the mouth and decreased upstream. The estuarine turbidity maxima zone was observed in both seasons, however, the increase in river discharge, during the rainy season, attenuated and displaced this zone seaward. The tide propagated asymmetrically, with hypersynchronous behavior near the mouth, being attenuated upstream. Regarding sedimentary organic matter, the data showed that estuarine samples present more negative δ13C values, as a result of stronger terrestrial and mangroves influences. The δ13C values of samples collected on the inner shelf showed less negative values, indicating a mixture between marine and mangrove carbon sources. Furthermore, the results showed that the size of the drainage basin of local rivers is also a relevant factor in the dynamics of organic matter. The Gurupi River, for example, is large enough to contribute organic and terrigenous sediments to the estuary and internal shelf. In summary, the SACZ estuaries are characterized by the macrotidal regime, subject to singular aspects of geology, geomorphology and the local river. In the Mocajuba estuary, inherited morphology had a strong influence on hydrodynamic and sedimentary processes. In the Gurupi estuary, the high river flow played a fundamental role in the estuarine dynamics.Tese Acesso aberto (Open Access) Evolução crustal do setor Sul da Província Borborema: Domínio Macururé, sistema Orogênico Sergipano, nordeste do Brasil(Universidade Federal do Pará, 2023-09-29) PEREIRA, Fábio dos Santos; ROSA, Maria de Lourdes da Silva; http://lattes.cnpq.br/9814085660417748; https://orcid.org/0000-0002-5099-829X; LAFON, Jean Michel; http://lattes.cnpq.br/4507815620234645; https://orcid.org/0000-0003-0854-3053The Sergipano Orogenic System (SOS), located in the southern Borborema Province, is part of a large Brasiliano/Pan-African orogen structured during the Gondwana supercontinent assembly, which spread out to central Africa up to Cameroon. Six domains compose the SOS, namely Estancia, Vaza Barris, Macurure, Maranco, Poco Redondo, and Caninde. The Macurure Domain stretches 350 km from the Sergipe coast to Macurure City, Bahia state. It consists of a succession of quartzites overlaying by a thick package of phyllites, schists, metarhytmites, and metagraywacke, with intercalations of amphibolite and calc-silicate rocks. The rocks were metamorphosed under greenschist-amphibolite facies and intruded by numerous late Cryogenian-Ediacaran granites and mafic plutons. In this work, new geochemical, U-Pb geochronological (zircon and titanite), and isotopic (whole-rock Rb-Sr, Sm-Nd, and Pb-Pb and in situ zircon Lu-Hf) results from the main units composing the Macurure Domain allowed to refine the local stratigraphy and improve the comprehension about sources and processes involved in the generation of the magmatic rocks. U-Pb isotope analyses on detrital zircon from quartzites yielded two main peaks in the ranges of 1980-1950 Ma and 1000-910 Ma, consistent with the Rhyacian Orogeny (2.2-1.9 Ga) e Cariris Velhos event (1.0-0.9 Ga). Paleoproterozoic dates overlap those observed in the Provincia Borborema basement, represented in the study area by the Jirau do Ponciano Dome and Arapiraca Complex. Negative to slightly positive εHf(t) values between -15.6 and +0.5 and Hf-TDMC model ages from 2.5 to 3.5 Ga characterize this population, suggesting extensive reworking of the Archean crust during the Rhyacian-Orosirian periods. Early Neoproteozoic zircon grains display sub- to superchondritic Hf isotope composition (-12.3 to +7.7) and Hf-TDMC model ages from 2.5 to 1.3 Ga, implying the addition of juvenile material and reworking of preexistent crusts during the Cariris Velhos event. Less abundant Mesoproterozoic (1120-1040 Ma) and late Neoproterozoic (880-740 Ma) zircon populations suggest that the sediment deposition took place before the Brasiliano Orogeny. The groups of magmatic rocks were individualized based on field, petrographic, and geochemical features. (i) The oldest plutonic rocks in the area are diorites and gabbros, with minor cumulate hornblendites. They generally show evidence of solid-state deformation and well-developed tectonic foliation, defined by the plagioclase, hornblende, and biotite orientations. These features point to emplacement in a pre- to early-collisional stage between 643 and 628 Ma. Geochemical data reveal a magnesian nature and affinities with the high-K calc-alkaline and shoshonite magmatic series. REE and multielement spectra exhibit enrichment in light REE and large ion lithophile elements, with deep troughs at Ti-Nb-Ta, typically interpreted as a subduction setting signature. Whole-rock isotope data indicate an evolved signature with subchondritic Nd (εNd(t) = -2.0 a -5.2) e radiogenic Sr (87Sr/86Sr(t) = 0.708-0.710), and Pb (206Pb/204Pb = 18.50-19.18; 207Pb/204Pb = 15.69-15.77; 208Pb/204Pb = 38.54-40.04), indicating derivation from an enriched mantle source. High 87Sr/86Sr(t) and Rb/Sr ratios, together with low Sr/Th and Ba/Rb ratios, suggest that the enrichment episode occurred in response to the introduction of sedimentary components in the mantle via subduction processes, leading to the formation of phlogopite as the main metasomatic phase. Hf-TDMC model ages between 2.47 and 2.09 Ga suggest that the enrichment of the lithospheric mantle beneath the southern Borborema Province occurred during the accretionary events of the Rhyacian Orogeny. Incorporating sediments by the mantle peridotites may have led to increasing Rb/Sr, (U-Th)/Pb coupled with decreasing Sm/Nd and Lu/Hf ratios, which resulted in the time-integrated crustal signature observed in the mafic rocks. (ii) Biotite- and muscovite-bearing leucocratic granodiorites, monzogranites, and syenogranites outcrop as stocks and sheets. They show magmatic foliation marked by the orientation of micas and surmicaceous enclaves, parallel to the schistosity of country rocks, indicating synchronous emplacement to the collisional event between 630 and 624 Ma. Leucogranites are metaluminous to strongly peraluminous, high-K calc-alkaline, and magnesian to ferroan. εNd(t) values and Nd-TDM model ages overlap those of their host5 rocks, suggesting derivation from mostly sedimentary protholiths. (iii) The younger group consists of monzonites, quartz-monzonites, granodiorites, and granites, with crystallization ages from 625 to 603 Ma. They are predominantly isotropic and truncate the regional foliation of the country rocks, indicating a late emplacement relative to the collisional event. The metaluminous and magnesian signatures, with high-K calc-alkaline and shoshonite filiations, resemble the composition of experimental liquids obtained by partial melting of basalt protoliths moderately enriched in incompatible elements. Lu-Hf isotope data provided subchondritic εHf(t) values between -8.3 and 4.0 with Hf-TDMC model ages from 1.77 to 2.03, indicating the reworking of ancient continental crust, possibly related to the Cariris Velhos event. The geochemical and isotopic data of this study, together with those available in the literature allows us to infer that the Neoproterozoic geodynamic evolution of the SOS along the western Gondwana margin can be explained by a lithospheric extension of the Borborema Province basement, followed by basin inversion, and continental collision.Tese Acesso aberto (Open Access) Estudo isotópico do depósito aurífero Volta Grande, domínio Bacajá, sudeste do cráton amazônico(Universidade Federal do Pará, 2024-03-22) PIMENTEL, Helmut Sousa; VASQUEZ, Marcelo Lacerda; http://lattes.cnpq.br/4703483544858128; https://orcid.org/0000-0003-2729-9404; MACAMBIRA, Moacir José Buenano; http://lattes.cnpq.br/8489178778254136The area of the Volta Grande of the Xingu River is crucial for the geological understanding of the Siderian and Riacian periods in the Bacajá Domain, Maroni-Itacaiúnas Province, Amazonian Craton, which hosts significant gold mineralizations. The Bacajá Domain is composed of tectonic associations with NW-SE orientation that contain reworked Archean and Siderian fragments, mainly during the Riacian, with significant crustal growth during the Transamazonian Cycle (2.26 to 2.06 Ga). The objective of this thesis is to investigate the tectonic environment and discuss the crustal evolution in accretionary and continental collision settings. The study relied on field surveys, geological-geophysical mapping, petrography, geochemistry, geochronology, and isotopic geochemistry, employing U-Pb and Lu-Hf methods in zircon via SHRIMP and LA-ICP-MS, U-Pb in titanite via LA-ICP-MS and Sm-Nd on whole rock via TIMS. The geological-geophysical integration reveals the NW-SE trending Bacajá Shear Zone with well-defined edges and foliated terrains of high magnetic susceptibilities, plastically deforming the lithotypes within. Petrographic analyses identified metavolcanosedimentary rocks of the Três Palmeiras sequence, the Intrusive Oca Suite (composed of granodiorite, quartz monzodiorite, quartz monzonite, monzodiorite, and diorite), as well as granodiorite, monzogranite, and sienogranite of the Bacajaí Complex and the Arapari Intrusive Suite. The zoned hydrothermal orogenic gold mineralization occurs at the contact between the Três Palmeiras Group and the Intrusive Oca Suite. The geochemistry of mafic volcanic rocks from the lower Itatá Formation of the Três Palmeiras Group indicates evolved tholeiitic character in a mid-oceanic ridge and juvenile island arc setting, while the volcanic rocks of the upper Bacajá Formation are related to calc-alkaline volcanic arcs in active compressional continental margins. Three groups of granitoids representing different phases of magmatic and tectonic evolution in the Bacajá Domain during the Riacian were distinguished, with ages spanning around 110 M.y.: granitoids from the Intrusive Oca Suite at 2.20-2.17 Ga, syenogranite with biotite from the Bacajaí Complex at 2.17 Ga, and biotite-bearing monzogranite from the Arapari Intrusive Suite at 2.09 Ga. The Intrusive Oca Suite comprises intermediate to acid, calcic to alkali-calcic, ultramafic to medium-mafic, metaluminous to peraluminous rocks formed in a cordilleran granitic setting related to volcanic arcs. The REE of Intrusive Oca Suite granitoids exhibit strong magmatic fractionation, reflected in high (La/Lu)N ratios, enrichment in Rb, Th, and K, and depletion in Ba, Nb, P, and Ti, sourced from mafic rocks with varying K contents. The Bacajaí Complex consists of calcic to alkali-calcic, medium-mafic, and peraluminous quartz monzonite, granite, and granodiorite, sourced from x mafic rocks with low-K and high-K components and some input from metasediments. The rocks of the Arapari Intrusive Suite are medium-mafic, calcium-alkali to alkali-calcic, and metaluminous, sourced from mafic rocks with high-K content. The syn- to late-collisional granitoids (Bacajaí Complex and Arapari Intrusive Suite) are enriched in LILE and LREE, exhibiting negative anomalies in Ni, P, and Ti, and depletion in HFSE, typical of orogenic granites in volcanic arcs. In terms of isotopes, the Três Palmeiras sequence has Nd-TDM values ranging from 2.35 to 2.58 Ga, with εNd(t) varying from -0.41 to +3.20. The Intrusive Oca Suite includes rocks with Nd-TDM between 2.24 and 3.06 Ga and εNd(t) ranging from -5.99 to +2.44. U-Pb zircon crystallization ages for this suite are 2203 ± 23 Ma, with Hf-TDM C values between 2.4 and 2.8 Ga and εHf(2.20Ga) ranging from -0.45 to +5.24 for the Ouro Verde body; 2173 ± 7 Ma with Hf-TDM C ranging between 2.3 and 2.6 Ga, and ɛHf(2.17Ga) between +2.04 and +7.65, added to a U-Pb age of 2171 ± 17 Ma in titanite, for the Central body, and 2171 ± 13 Ma, with Hf-TDM C values between 2.4 and 3.4 Ga and εHf(2.17Ga) ranging from -10.32 to +4.34 for the Buma body, indicating distinct crustal generations between the Mesoarchean and Siderian/Riacian. The Bacajaí Complex has a crystallization age of 2165 ± 10 Ma, Hf-TDM C values between 2.5 and 2.8 Ga, and εHf(2.16Ga) ranging from -0.35 to +3.04, with mantelic sources from the Neoarchean. The Arapari Intrusive Suite has a crystallization age of 2094 ± 13 Ma, Nd-TDM at 2.38 Ga, εNd(2.09Ga) at -1.15, Hf-TDM C values between 2.6 and 2.8 Ga, and εHf(2.09Ga) varying from -2.77 to +1.59, indicating a mixture of mantle and crustal sources generated from the Neoarchean to the Siderian. The geological evolution of the study region is marked by various events. In the Siderian, volcanic-sedimentary sequences with tholeiitic basalts and island arc andesites were followed by the emplacement of diorites to granites around 2.20 to 2.09 Ga and collision, originating continental arcs. The most advanced and late stage of the Transamazonian orogeny in the Volta Grande region is represented by the emplacement of peraluminous granitoids from the Arapari Intrusive Suite, closing the complex geological bevolution of the region. The analyses in this study highlight the proposed similarity based on petrographic, geochronological, and isotopic similarities between the Volta Grande region and the Lourenço and Carecuru domains, located in the state of Amapá, in the northeastern portion of the Maroni-Itacaiúnas Province.Tese Acesso aberto (Open Access) Proveniência dos arenitos dos grupos Canindé, bacia cratônica do Parnaíba, por termocronologia e geocronologia em zircão detrítico.(Universidade Federal do Pará, 2023-11-27) OLIVEIRA, Camila Vilar de; MOURA, Candido Augusto Veloso; http://lattes.cnpq.br/1035254156384979Before the most severe Late Paleozoic Ice Age, the Western Gondwana was affected by short-lived glaciations recorded in several intracratonic basins from Northern South Amer ica. The Famenian-Tournasian coastal marine successions exposed in the Sulamerican plat form represent a window of opportunity to unravel the different source lands using U-Pb ages of detrital zircon grains during the icehouse and greenhouse conditions. The Famenian Tournasian Cabeças Formation in the intraplate Parnaiba basin, Northern Brazil, represents a glaciomarine system of the ice contact delta developed at the Western Gondwana Margin. Preglacial deltaic deposits indicate two significant U-Pb age peak ranges of 768-448 Ma and 1175-937 Ma, suggesting drainage from the East of Western Gondwana. In contrast, U-Pb age peak ranges of 1998-1731 Ma and 1079-894 Ma show sources from the South supplying the northwestern glacier advance on the coastal-marine settings. During the initial greenhouse phase, the ice-melt deltaic system provided zircon ages of 1093-817 Ma, indicating the retak ing of the preglacial source lands. The sampling for age acquisition combined with precise paleoenvironmental interpretation offers, for the first time, high-resolution information that supports a most robust paleogeographic reconstruction of the Western Gondwana during the Late Paleozoic. Additionally, the use of Hf isotope and fission track proxies linked to a sys tematic morphological description, internal structure, and Th/U ratio applied to Mesoprotero zoic-Tonian detrital zircons, focused on the main detrital age spectra of glacial deposits, al lowed reveals the discrimination of competing sedimentary source land regions and recogniz ing detrital contributions from the provenance dynamic of ancient orogenic settings, such as the West Gondwana and Araçuai-West Congo orogens.Tese Acesso aberto (Open Access) Mudanças da cobertura, uso do solo e produção de minério de ferro em minas a céu abertona Austrália e no Brasil: um indicador de intensidade de explotação mineral(Universidade Federal do Pará, 2023-05-26) SANTOS, Diogo Corrêa; SOUZA FILHO, Pedro Walfir Martins e; http://lattes.cnpq.br/3282736820907252Iron ore is a very important resource for the development of a nation. With technological, industrial and urban advances, especially in Asian countries, the demand for this resource has increased considerably in recent decades. Consequently, changes in land cover and use (LCLU) have occurred in the mined areas of countries with higher ore production. Australia and Brazil are the largest iron ore producers in the world. In 2019, they reached production amounts of 930 million tons (mt) and 480 mt, respectively. However, little is known about the extent of land required for iron ore exploitation at the scale of productive open-pit mines in these two countries. Therefore, this doctoral thesis aimed to (1) map the LCLU in time and space in iron mining areas in the countries with the highest production in the world; (2) estimate the area used for iron ore exploitation as well as the accumulated ore production from the 1980s to 2019; and (3) identify an indicator of mineral exploitation intensity and ore production in millions of tons per square kilometer (mt/km²) for the main iron mines in Australia and Brazil. Landsat 5 TM (1984 and 1986) and Sentinel-2B (2019) satellite images were processed to map LCLU in areas of open cast iron mines in the Pilbara region of Western Australia, Hamersley mineral province and in the regions of Carajás (PA), Corumbá (MS) and Quadrilátero Ferrífero, QF, (MG) in Brazil, using geographic object-based image analysis (GEOBIA). The values of iron ore production per mined area were extracted from the statistical yearbooks of mineral production in the two countries. The results showed that iron mining in Australia occupied an area of 41.45 km² in 1986 and was expanded to 875.06 km² by 2019. In Brazil, the extent of iron mining was 109.53 km² in 1984, and this area expanded to 295.75 km² in 2019. The overall accuracy and kappa index of the set of classified images were above 90%, indicating the excellent quality of the classification. The accumulated iron ore production data between 1984 and 2019 showed that Australia reached a total production of 8.4 billion tons of iron ore in this period in a mined area of 875.06 km², equivalent to 9.7 mt/km². Brazil reached a total production of 7.03 billion tons in an area of 297.75 km². The mineral exploitation intensity indicator showed that Brazil and Australia produced equivalents of 23.6 mt/km² and 9.7 mt/km², respectively, over the study period. The study concluded that (1) the area of mined soil increased in all the mines in the two countries analyzed between 1984 and 2019, with the largest expansion being detected in Australia; (2) the high production of iron ore in Australia and Brazil and the consequent LCLU changes are driven by high demand from Asian countries, especially China; and (3) according to the mineral exploitation intensity indicator, there was a better relationship between mineral production and mined area in Brazil than in Australia. This result allows us to confirm that the two countries, especially Brazil, reached extremely high levels of production in a proportionately small area. Finally, this doctoral thesis contributed to the understanding of the intensity of iron ore production and the consequent LCLU changes in these two countries in addition to contributing quantitative and specialized data on the extents of the main iron ore mines globally.Tese Acesso aberto (Open Access) Geologia, geoquímica e isótopos (U-Pb, Lu-Hf e Sm-Nd) de granitos orosirianos do Domínio Iriri-Xingu setentrional, Província Amazônia Central(Universidade Federal do Pará, 2023-03-29) ALCÂNTARA, Davi da Costa Bezerra Gobira; VASQUEZ, Marcelo Lacerda; http://lattes.cnpq.br/4703483544858128; https://orcid.org/0000-0003-2729-9404; MACAMBIRA, Moacir José Buenano; http://lattes.cnpq.br/8489178778254136The Orosirian of SE Amazonian Craton is mainly characterized by igneous associations from I, A and rare S types outcropping from west to eastward, in the Tapajós, Iriri-Xingu and Carajás domains. The Carajás domain represents the oldest crustal region, stabilized during the Neoarchean. The Tapajós domain represents, at least to some extent, the proximal region of a continental margin actived during the Orosirian. The Iriri-Xingu domain (IXD), at the center, still holds an uncertain tectonic role. These igneous associations were formed in multiple magmatic episodes through this geological period, which can be temporally divided in three intervals. The first interval, from 2030 to 2000 Ma, is marked by a juvenile, I-type, calc-alkaline volcano-plutonism in the Tapajós domain. The second interval, from 2000 to 1960 Ma, is marked by a series of I type, high K calc-alkaline to shoshonitic rocks that expands from Tapajós domain to the east, in the IXD. The rocks of the third interval (1900 to 1860 Ma) are represented by an I type calc-alkaline magmatism and an A type magmatism, the later associated to mafic rocks. The A type rocks, typically from A 2 sub-type, belong to a broader geographical context than the I type magmatism, and outcrop in an expressive area through the Amazonian Craton (ca. 1,500,000 km 2 ). These rocks are generically attributed to the Silicic LIP Uatumã. In this thesis, we concentrate on the plutonic part of these associations and present new geological, lithochemical and isotopic (U-Pb, Lu-Hf in zircon and whole rock Sm-Nd) data for granites of the second and third magmatic episodes from central-eastern and northern IXD. In central-eastern IXD, the granites São Pedro do Iriri, Vila Primavera, Caboclo and Jabá present an alkaline to subalkaline, metaluminous to slightly peraluminous, ferroan to slightly magnesian character. The first three granites are akin to the reduced tin-specialized A type granites of Velho Guilherme Suite, from Carajás Domain. U-Pb and Lu-Hf data provided a crystallization age of 1897 ± 8 Ma for the São Pedro do Iriri Granite, and εHf (t) values (from -8.22 to -17.44) that point to a mixing of meso and paleoarchean crustal sources. The Jabá Granite exhibits geochemical affinity to the oxidized A type granites from Iriri-Xingu and Carajás domains. This granite yielded a U-Pb in zircon crystallization age of 1887 ± 14 Ma and εHf (t) values of -6.43 to -10.21, indicating a more radiogenic, homogeneous and predominantly mesoarchean crustal source. The classic I type calc-alkaline rocks studied in this work comprise the Rio Bala, Porto Estrela and other sparse granitic samples from Iriri river that represent, among others plutons, the Serra do Chavito and Pedra do O granites. They are amphibole and biotite bearing rocks that show magnesian, metaluminous, high K calc-alkaline to slightly shoshonitic character. The Porto Estrela Granite exhibits tonalitic to granitic facies and yielded a U-Pb age of 1972 ± 6.6 Ma. The samples of the calc-alkaline granites from Iriri river are quartz-monzonitic to granitic in composition. Samples from the Serra do Chavito and Pedra do O granites yielded ages of 1987 ± 6.6 and 1988 ± 8 Ma, respectively. The ages yielded by the Porto Estrela and the Iriri river’s granites correlate these rocks to the second interval volcano-plutonic association of Iriri-Xingu and Tapajós domains. The Rio Bala Granite is quartz-monzonitic and granitic in composition, exhibits a chemical trend typical of subalkaline rocks and yielded a U-Pb in zircon age of 1877 ± 8.2 Ma. This granite represents the first record of a high K calc-alcalic plutonism coeval to the volcanic rocks of the Iriri Group (1.88-1.87 Ga calc-alkaline rhyolite and dacite) in IXD. Chemically, it presents a more evolved character and affinity to the granitic facies of Parauari Suite. The remaining studied rocks of the central and northern IXD comprise two atypical samples of A type and I type granites, that represents respectively the Cachoeira do Julião and Igarapé Limão plutons. The A type granite sample is a cpx-hb-bt quartz-syenite. Its petrographical, chemical and previous geochronological data (1889 ± 3 Ma) allow a correlation with the plutonic rocks of the Uatumã SLIP. The other sample constitutes a biotite monzogranite of magnesian, slightly peraluminous, medium to high K calc-alkaline character, similar to the I type adakitic rocks. The REE curved upwards pattern and the relatively low Dy/Yb ratio (1.04) suggest residual amphibole or its fractioning in relatively high P in presence of garnet. The low contents of MgO, #Mg, Yb and Ni, and high FeO t /MgO ratio indicate an affinity to the adakites of thickened lower crust melting. The necessary conditions to this rock genesis are satisfied if we consider the IXD crust to be deformed and thickened in the Transamazonian Cycle and latter thinned in the Orosirian. The data related to the I type magmatism with ages of 2.00 to 1.96 Ga suggest an extensive but brief event, with a minimum area of 190,000 km 2 and lifespan of 40 M.y. Extrapolating modern geodynamical conditions for subduction to the Paleoproterozoic, it is concluded that the space-temporal pattern of this magmatism cannot be uniquely explained by subduction process. Therefore, it is inferred that at least part of this magmatism should be generated in a convergent margin by other process than subduction or, alternatively, a post-orogenic event. The same reasoning can be adequately projected to the 100 M.y. younger calc-alkaline rocks of the third time interval (1.90–1.86 Ga). The Nd isotopic data for the studied rocks present moderately to highly negative εNd (t) values and siderian to mesoarchean Nd-T DM model ages. The available data, presented in this work and from literature, reveal a heterogeneous crust, partly composed by a crust similar to the Carajás’. The neoarchean and siderian isotopic signatures could represent, in a non-mutually exclusive way: the presence of juvenile crustal segments; mixture of ancient archean crust and mantellic input (probably from Ryacian and/or Orosirian); or mixture of diverse crustal components. This crust could be interpreted as paleo to mesoarchean preserved nuclei bordered by reworked crust that probably underwent juvenile inputs on Ryacian and/or Eo-Orosirian, besides presenting isolated blocks/segments of juvenile Neoarchean and Ryacian rocks. Concerning the IXD lithostratigraphy, we suggest the Iriri Group to be composed by the Santa Rosa – acid A type volcanics - and Confresa – acid I type calc-alkaline volcanics – formations, both with crystallization ages within 1.90 and 1.86 Ga. We propose the 2.00 to 1.96 Ga calc-alcalic volcanic rocks, formerly related to the Iriri Group, to be grouped in the Jarinã Formation. We also recommend the adoption of the term Vila Rica Suite to refer the I type granites coeval to the Jarinã Formation. We also endorse grouping the A type granites akin to the oxidized granites of Carajás in the Rio Dourado suite. In respect to the potentially tin-specialized reduced A type granites, we recommend this group of rocks to be assembled in the proposed São Pedro do Iriri Suite.