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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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Acesso aberto (Open Access)
Análise evolutiva da paisagem da serra Tepequém - Roraima e o impacto da atividade antrópica
(Universidade Federal do Pará, 2008-01-23) BESERRA NETA, Luiza Câmara; BORGES, Maurício da Silva; http://lattes.cnpq.br/1580207189205228; 1580207189205228; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302; 1639498384851302
The north area of Roraima State presents great diversity of geomorphologic featuresformed by dissected plateaus, limited by intermountain plain and relief with a plateau morphology that it is individualized in the extensive plain areas, e.g., of the mountain Tepequém. Since 1930s this was a site of intense activity of diamond extraction what printed changes in the landscape. The main objective of this study is to understand the dynamics evolution of the landscape of the mountain Tepequém under diamond extraction activity and the reason of its erosion susceptibility, being natural or anthropic. To reach these objectives, a description of profiles of soils and saprolitic rock, as well as lateritic profiles were accomplished. Samples of soils, altered rocks, laterites and coal were collected. Besides, width, depth, extension and directional alignment of the channels of the gullies measurements were carried out. The collected materials were submitted to the following analyses: grain size, by humid way; minerals identification by X-ray diffraction and SEM techniques; total chemistry analysis (major elements) by ICP-MS and content of organic matter, humidity and density of the soil measurements. Coal samples were submitted to radiocarbon analyses by AMS (Accelerator Mass Spectrometry). Appling the interpretation of optical images (Landsat-5/TM and Cbers-2/CCD) and the cartographic base, maps of structural alignment, relief (altimetry and declivity), drainage and vegetation covering were also elaborated. The mountain Tepequém stand out among the landscape dominated by relief of hills, residual hills and plane-slightly wavy surfaces because of its rectangular-rhombic format and outline of steep scarps elaborated on sedimentary rocks of Paleoproterozoic. The drainage system of the area delineates parallel, angle-rectangular and faults standards. The relief and drainage morphology of the mountain Tepequém and its around area define a subordination to the structural arrangement E-W, NE-SW and NW-SE directions represented by normal and strike-slip faults. In the mountain Tepequém, the geomorphologic compartments are established by 575 to 670 m high plain intra-valleys surfaces bordered by less than 774m high hills and residual hills and edge slopes less than 1100m high. The bush grassy savanna dominates this landscape and recovers the edge scarps and extends along the regional plain. The ciliary forest covers small stains along the Cabo Sobral and Paiva rivers. This scenery was quite modified because of diamond extraction activity. However, with the decline of this activity, the ciliary forest recovers spontaneously, as the optical images of the last 22 years shows (1984, 1995 and 2006). Intra-valleys plains were developed on sandy soils constituted by medium and fine grain size sandy domains, sub-angles to sub-rounded poorly selected, with low cohesion and small quantity of organic matter. These soils are developed on saprolitic derived of sandstones and siltstones. Locally stone lines and colluvial are observed, usually on the saprolitic. Immature laterites are found in the center-north hills of the mountain Tepequém. Quartz, muscovite in sub-milimetric plates and kaolinite partially involving the grains of quartz are predominant in soils constitution, while the lateritic profiles are constituted by gibbsite, goethite and hematite, besides quartz and kaolinite. Laterite and quartz fragments constitute the stone lines. High concentrations of SiO2 confirm the essentially quartz-character of the soils, while the values of Al2O3, K2O, MgO, Fe2O3 and TiO2 are more expressive in the saprolitic zones, confirming the kaolinite, muscovite and hematite domain, derived of claystones and siltstones. The radiocarbon ages in coal obtained for the superficial materials (colluvial and stone lines) show that these materials were formed at least 3.822 years BP. The intermountain plains reveal in its landscape erosive features in the piping formations, dolines and gullies, developed in the lands with sandy to silt materials domain. The channels of gullies are mainly aligned in the directions NE-SW and NW-SE corresponding to the directions of fractures and faults that section the Tepequém Formation. The seemingly stabilized gullies are partially covered by ferns that grow on the side and bottom surfaces of the channel. The evolution of the landscape of the mountain of Tepequém specially the formation of its general internal structure involves the tectonic still in Proterozoic. The inherited morphology reflects in the steep scarps around as well as in the top such a great synclinorium. The evolution of the landscape of the mountain of Tepequém during Cenozoic is marked by formation of small hills, some of these protected by lateritic crusts suggesting registration of a humid and hot paleoclimate in Pleistocene, which can admit the installation of the drainage net. The erosive process of the fluvial courses allies with the high gradient favored the transport of part of the sediments to W-SW direction, contributing in the formation of the intermountain plains. The current scenery is marked by the erosive retaking favored by the sandy non-cohesive nature of the soils, ally to a paleorelief inclined to the valleys and strongly fractured and failed that causes a strong shallow surface stormflow propitiating the piping formations, dolines and then the gullies. Thus, the diamond extraction activity can contribute in the intensification of the gullies but, however, it was not the decisive factor. Therefore, the evolution of the landscape of the mountain Tepequém in Proterozoic and in Cenozoic until the present is due to the interaction of multiple processes involving the tectonic history, the weathering changes and the several erosion cycles, as well as the restricted sedimentation and the small anthropic contribution.
Acesso aberto (Open Access)
Aplicação da composição isotópica de multielementos no monitoramento ambiental de área circunvizinha à barragem de rejeito: o caso da mina de cobre da Serra do Sossego, Canaã dos Carajás – PA
(Universidade Federal do Pará, 2017-06-09) OLIVEIRA, Simone Pereira de; MOURA, Candido Augusto Veloso; http://lattes.cnpq.br/1035254156384979
Tailings dams from ore mining activities are relevant compartment for environmental monitoring because the dam can present undesirable forms of water outlets such as infiltration. The present thesis proposed multielement isotope study in order to evaluate the use of the isotopic composition of oxygen, hydrogen, strontium and lead as a tool for the environmental monitoring of groundwater vulnerable to the tailings dam. This research was conducted in the area of the Serra of Sossego copper mine and, in addition to the isotope study, the hydrochemical characterization of groundwater and surface water was caried out. Besides, the direct reading of the isotopic composition of lead (without chemical treatment of the water sample) was applied for the first time, using multicollector inductively coupled plasma mass spectrometry, in the laboratory Para-Iso. The hydrochemical characterization of groundwater in the Serra do Sossego mine area showed that it is moderately acid (pH ~ 6). Only the AP15 and PS32 wells, under the influence of the drainage of the mixed pile (ore waste + sterile), presented high electrical conductivity (599 μS / cm2 and 694 μS / cm2) and the higher sulfate content (1.82 to 6.57 Meq/L). In general, iron (29.7 mg/L), manganese (69.7 mg/L) and copper (24.9 mg/L) present the highest metal content in the groundwter. In terms of the isotope studies, the groundwater of PS17, PS04, AP15 and PS32 wells and the water of the Dam present the least radiogenic lead isotopic composition. The water sampled in the AP15 and PS32 wells would be representative of the lead isotope signature of groundwater in the mine area (206Pb/207Pb = 1.1481 to 1.1663) and, probably, is indicative of the lead isotope composition of the meteroric water. The lead isotope composition of the groundwater of the wells PS04 (206Pb/207Pb = 1.1784-1.1850) and PS17 (206Pb/207Pb = 1.2100 to 1.2160) may indicate a small contribution of the rocks of the region (206Pb/207Pb > 1.6807). In turn, the lead isotope signature of water of the Dam (206Pb/207Pb = 1.2279) suggests, as expected, a slightly more pronounced contribution of the ore and the rocks. On the other hand, the lead isotopes of the water sampled in the wells MNA23 and PS06 show a more radiogenic signature (206Pb/207Pb = 1.6741 to 1.9196), which is similar to those of the chalcopyrite and the diabase of the Sequeirinho open pit, revealing a more significant contribution of the ore and rocks. As the lead isotope composition of water from the dam is different from that of the groundwater, it can be used for the environmental monitoring of the influence of the water from the dam in groundwater in the Serra of Sossego mine area. In those wells with less radiogenic lead isotope signature, a possible contribution of the water from the dam would result in a more radiogenic lead isotope composition in the groundwater. Conversely, in those wells with more radiogenic lead isotope signature, a contribution of the water dam for the groundwater would decrease the values of the measured lead isotope ratios. On the other hand, the application of the sulfur isotopes for environmental monitoring presented some limitation in the study area, due to the lack of contrast of the sulfur isotope composition among the sulfides of the Sossego deposit (δ 34S ~ 2-7 ‰), the water from the dam (δ 34S ~ 2 ‰), and the drainage of the mixed pile (δ 34S ~ 2‰). This prevents the recognition of a possible contribution of the tailings dam to groundwater. Mixing models using the 87Sr/86Sr ratio as a function of the strontium concentration and δ 18O values, also showed some limitations, since there is no contrast between the values of the 87Sr/86Sr ratio of the water from the dam (0. 7458 to 0.7539) and the rocks of the mine area (granite ~ 0.7474). Such similarity, in principle, would not allow identifying the contribution of the water from the dam. However, since groundwater generally exhibits less radiogenic values of the 87Sr/86Sr ratio (0.7161 to 0.7283) and well below the dam values, the strontium isotopic composition can be used for environmental monitoring of groundwater. Hydrogen and oxygen isotope data revealed that, in the rainy season, the groundwater presented values of δ 18O and δ D varying from -2.74 to -7.17‰ and from -15.6 to -46.0‰, respectively. In turn, an enrichment of 18O and D, with values of δ 18O between -1.67 and -7.29 ‰ and of δ D between -0.23 and -46.1 ‰, is observed in the dry season. Hydrogen and oxygen isotope composition of the water from the dam (δ 18O from 1.24 to 2.79 ‰ and δ D from 1.40 to 7.0 ‰) is very different from those of the groundwater and of the drainage of the pile. A mixing model performed with oxygen and hydrogen isotopes showed that these elements are the ones that best respond as indicators of the contribution of the waters from the dam to groundwater. The application of this model revealed no influence of the water from the dam on the groundwater during the period of this study. The results obtained in this multielement isotopic study suggest that the environmental monitoring of the groundwater of the Serra do Sossego mine to investigate the possible contribution of the water from the dam, can be done more efficiently with the oxygen and hydrogen isotopes. The isotopic compositions of lead and strontium can also be used for monitoring the groundwater, but this has to be done more systematically due to the small contrast between the isotopic composition of these elements in the dam water and in the groundwater. Finally, the isotopic composition of sulfur is the one that would contribute least to the environmental monitoring of the groundwater of the study area.
Acesso aberto (Open Access)
Aplicação de resíduos da mineração de bauxita na síntese de geopolímeros
(Universidade Federal do Pará, 2022-04-08) BARRETO, Igor Alexandre Rocha; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302; https://orcid.org/0000-0002-0134-0432
The process of extraction and beneficiation of bauxite deposits in the bauxite province of Paragominas/Rondon do Pará can generate large amounts of waste, mainly in two stages of the process: mining and processing. In the mining stage of the deposits, the “residue” comes from the removal of a thick layer of clay material (known as Belterra Clay). On the other hand, the “residue” from the beneficiation process is generated after the crushing, grinding and washing stages, which give rise to a large amount of clay material dispersed in a large amount of water. For the present study, it selected Belterra clay from the bauxite deposits of Rondon do Pará, a sample of Bauxite Washing Clay from the Hydro company and a sample of kaolin benefited from Imerys Company. The samples and geopolymers were characterized by X-ray Diffraction (XRD), X-ray Fluorescence (FRX), Gravimetric Thermal Analysis (TG), Differential Exploratory Calorimeter (DSC), Optical Emission Spectrometry with Coupled Plasma (ICP-OES) and Laser Particle Analyzer (APL). Geopolymers were synthesized from Belterra clay, microsilica and NaOH according to the Box-Benkhen design. Synthesis of geopolymers from Belterra clay and beneficiated kaolin was also carried out (a comparative study) using KOH and microsilica. Finally, geopolymers were synthesized from Bauxite washing clay with NaOH and microsilica according to the Doehlert design. In the study with only Belterra clay, the highest resistance result was 47.78MPa and the lowest result was 7.05MPa. In the comparative study between Belterra Clay and beneficiated kaolin, the best results of compressive strength were obtained with the beneficiated kaolin. The compressive strength results of the geopolymers synthesized from the Washing Clay ranged from 8.99 to 41.89MPa. These results demonstrate the positive potential of both samples for the synthesis of geopolymers that can be used as possible “Eco-friendly” substitutes for traditional materials, mainly ceramics and cement.
Acesso aberto (Open Access)
Aproveitamento dos resíduos cauliníticos das indústrias de beneficiamento de caulim da região amazônica como matéria-prima para fabricação de um material de construção (pozolanas)
(Universidade Federal do Pará, 2007-12-18) BARATA, Márcio Santos; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607; https://orcid.org/0000-0002-3026-5523
The Capim and Jarí regions are the most important kaolin district in the Amazon region, with the largest Brazilian reserves of high whiteness kaolin for paper coating products. Kaolin is obtained from three companies (IRCC, PPSA and CADAM) which produce annually around 1,000 M ton kaolinite-rich wastes derived mainly from the centrifugation phase of the process. The sludge is disposed on artificial sedimentary lakes covering large areas. Another type of kaolin waste is related to a non-processed iron-rich hard or flint kaolin, that overlays the so-called soft kaolin horizon (the main ore). These wastes exhibit appropriate characteristics for the production of high-reactivity metakaolin because they are extremely fine and composed of mainly by kaolinite. The main purpose of this work is to evaluate the feasibility of using these wastes as raw materials to produce mineral admixtures for OPC concretes. The wastes were firstly characterized for x-rays diffraction, thermal analysis, infrared spectroscopy, x-rays fluorescence and SEM. Three heating temperatures were evaluated: 750ºC, 850ºC and 900ºC, followed by pozzolanic activity tests based on traditional mechanical assays using Portland cement and hydrated lime mortars, and “Chapelle” test. The results showed that the more reactive pozzolans are those produced at temperatures that gave rise to higher LOI. The optimum burning temperature to produce metakaolinite from the hard kaolin was obtained at 750ºC while those from the Rio Jari and Rio Capim wastes were at 850ºC and 900ºC. The main reason is related to differences in the amounts of defects from three different wastes. The flint kaolin and Rio Jari waste are mainly composed by a “high-defect” kaolinite while the kaolinite from Rio Capim waste is a “lowdefect” kaolinite. In concrete test using different pozzolans those with metakaolin from wastes improved the mechanical and durability properties in comparasion to silica fume, a industrially manufactured metakaolin and reference concretes.
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/0000-0002-7271-4737
In 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.
Acesso aberto (Open Access)
Argamassas históricas de Belém do Pará.
(Universidade Federal do Pará, 2019-09-16) LOUREIRO, Alexandre Máximo Silva; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607
The city of Belém, northern Brazil, known as the metropolis of the Amazon, was established on the banks of the Guajará Bay on January 12, 1616, with the denomination of Nossa Senhora de Belém do Grão-Pará, capital of the Grão-Pará province, now the state of Pará. Currently, Belém still has layers of lime mortar on its colonial and imperial buildings, which protect the secular structures and provide evidence of how this material was produced early in its history. Over the years, the deteriorating aspects identified in lime mortars, which damage both aesthetics and functionality, are related to the humidity, saline efflorescence, biological colonization, and/or anthropic actions. Once deteriorated, mortars require maintenance, consolidation, or replacement, which are difficult procedures that can lead to the use of inappropriate materials. Therefore, a good collect and characterization strategies of the original material is necessary for the restoration of historical monuments, because in studies focused on restoration science, the intervention strategy needs to include the use of building materials compatible with the original materials. Thus, the main objective of this doctoral thesis is to determine the characteristics and properties of historical mortars in Belém do Pará from the 18th and 19th centuries, as well as to propose a restoration mortars compatible with the historic mortars, which using industrial waste from Amazon Region. Therefore, this thesis was structured in three independent and complementary thematic articles, which addresses the topic of the historical mortars of Belém do Pará, since their characterization until the proposal of restoration mortars: 1) Investigation of the historical mortar of Belém do Pará, Northern Brazil; 2) How to estimate the binder: aggregate ratio from aerial lime-based historical mortars for restoration? and; 3) The use of industrial waste of the Amazon region in lime-metakaolin restoration mortars: compatibility assessment. Thus, the physical, chemical and mineralogical characteristics were determined, as well as the physical and mechanical properties of the historical material and the restoration material. The results of the historical mortars characterization pointing their main components, their functions and raw materials, besides indicating the analytical techniques used for binder: aggregate ratio quantification, which obtained good accuracy and reliability in your results. Moreover, the results show a wide range of characteristics and properties obtained through restoration mortars, which can serve as a benchmark for other studies or even for practical applications in historic masonry. Therefore, it was possible to identify the restoration mortars most compatible with the historical mortars of Belém do Pará, Northern Brazil.
Acesso aberto (Open Access)
Biogeoquímica dos sedimentos lamosos e sua influência no padrão de distribuição da vegetação, no manguezal de Bragança, NE do Pará.
(Universidade Federal do Pará, 2009-10-30) CRUZ, Cleise Cordeiro da; LARA, Rubén José; http://lattes.cnpq.br/8695520453124286; 8695520453124286
The present study investigates the relationship between sediment-plant and biogeochemical processes involved in the development and spatial distribution of vegetation in the Bragança mangrove peninsula, exposed to macrotidal regime (spring range 4 m). Therefore, three transects were established at three different topographic levels of that peninsula being colonized by different patterns of vegetation: Transect 1 (T1) Transect 2 (T2) and herbaceous plateau (PHb). The vegetation in T1 is composed mainly by Rhizophora mangle and Avicennia germinans and it is situated in a semi-diurnal flooding regime forest. The transect T2 is less frequently flooded and is characterized by a stand of young Avicennia trees and herbaceous vegetation. In the highest part of this transect with low inundation frequency and high salt stress, the vegetation is dominated by shrubs of A. schaueriana coexisting with herbaceous vegetation of Sesuvium portulacastrum and Sporobolus virginicus. The PHB, localized in the zone with lowest inundation frequency is colonized mainly by tree species of A. schaueriana in the form of shrubs and S. portulacastrum and S. virginicus with sporadic presence of B. maritima. In these sites were performed measurements of the flooding frequency; floristic and fitossociologic inventory in mangrove forest and in the herbaceous halophyte vegetation. Also sediment cores (0-30 cm) and vegetation (leaves, stems and roots) were collected. The sediment samples were subjected to granulometrical, mineralogical and chemical (total sample) analyses, and determination of the humidity, organic matter and salinity as well as cation exchange capacity (CEC) besides determination of the total, inorganic, organic and bioavailable phosphorus. In the vegetation samples, chemical analysis of total phosphorus was performed. The variance analysis (ANOVA) One Way (Post Hoc Fisher's test) was applied to test the mean of the variables (humidity, salinity, organic matter, total-P, inorg.-P, org.-P and bioavailable-P. Discriminant analysis was used to measure the degree of influence of environmental variables (humidity, salinity, organic matter and total-P) in the discrimination of sites sampled. The correlation analysis of Pearson was used to evaluate the degree of interaction between discriminated variables with the hydrological conditions and forest structure data. Fine sediments (clay) in T1 and T2 suggest areas of slow deposition, while in the plateau high levels of sand suggest its formation on a paleodune with intense eolic reworking of sandy and tidal input of finer sediments. The main mineralogy of the sediments is composed of quartz (dominant in the sand and silt) and clay minerals: kaolinite and illite, other minerals of authigenic origin are pyrite, jarosite and vivianite and possibly smectite and k-feldspar. The main mineralogical and chemical composition of major and trace elements indicate the influence of sediments and soils of the Barreiras Formation on the genesis of sediments mangroves and marine influence in their chemical composition. In T1 (the more flooded sector), the dominant species is R. Mangle, while in T2 (less flooded zone) the Avicennia genus is predominant. In the herbaceous plateau the dominance of the S. portulacastrum species, is five times higher than that of S. virginicus, indicating that Sesuvium has greater ability to survive in environments with salt stress. The flooding gradient results in highly significant positive correlation with humidity. This trend is reflected in the tree height, volume and basal area correlated significantly with sediment phosphorus availability in T1 and CEC in T2. The results of Discriminant Analysis show that in T1 the humidity is the variable that most contributes in the discrimination of (Rhizophora and Mixed) forest of the Avicennia forest, while organic matter (OM) discriminated the Mixed forests and Rhizophora forests. In T2, the humidity, total-P and salinity are the variables that most contribute to the discrimination of sites in this transect. In the profiles, along the plain, the total-P and organic mater were the most important variables for discrimination of T1, T2 and PHb. The distribution of vegetation reflects different ecophysiological responses to environmental gradients. Therefore, the combination of organic matter, salinity, and phosphorus and, the high cation exchange capacity of sediments represent a significant role in the colonization of vegetation in the peninsula of Bragança.
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/0000-0002-5880-7638
Bentonites 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.
Acesso aberto (Open Access)
Desenvolvimento de processo para obtenção de zeólita do tipo faujasita a partir de caulim de enchimento, caulim duro e tube press: aplicação como adsorvente.
(Universidade Federal do Pará, 2015-03-31) ROCHA JUNIOR, Carlos Augusto Ferreira da; NEVES, Roberto de Freitas; http://lattes.cnpq.br/9559386620588673; 9559386620588673
The main purpose of this work is zeolite synthesis of faujasite type (X and Y) from kaolin from the beneficiation process for paper coating, hard kaolin or Flint (mining of waste), tube press kaolin and filler kaolin. For each process zeolitização kaolin used in a chemical reactor a product of calcination of each material (metakaolin), sodium metasilicate, solid sodium hydroxide and distilled water, subjected at 110 ° C, reaction time 13 h Si / Al ratio of 2, 4 and 6. The products of each zeolite synthesis as well as the starting kaolin were characterized by chemical, physical and mineralogical analyzes such as X-ray diffraction, X-ray fluorescence, electron microscopy scan and thermal analysis. From these tests, it was observed that all the kaolin showed the formation of faujasite zeolite, but with differences in the peak intensities and their associations with other zeolite phases. Hard kaolin showed a lower potential zeolitization into the Si / Al ratio equal to 2 compared with the other two supposedly related to the iron present in its composition, thus made was a removal process of this constituent, by Mehra and Jackson method to verify a possible maximization in the synthesis process. New results indicated a complete modifications to the area and degree of structural order of faujasita phase, now moving into a major phase and there is an increase in the degree of structural order. As this reaction condition for consumption and a lower cost of raw materials and energy for calcination This medium was used as a starting point for an experimental design to evaluate the best reaction conditions. This design was varied some parameters of the synthesis as temperature, reaction time, Si / Al ratio and H2O / Na2O. The results of the statistical design showed the formation of faujasite in 32 points of study, as well as a great region with 8 points of planning, in this region point 13 proved the best reaction conditions. The zeolite synthesized at this point, showed an increase of ammonium adsorption capacity and percentage near 85 % efficiency up to 60 ppm. The Langmuir model was more suitable than the Freundlich and Sips in agreement with experimental data. The thermodynamic parameters showed that adsorption of NH4 + is a spontaneous and exothermic process, in which the temperature rise from 25 to 60 ° C promotes a small decrease in the adsorption capacity.
Acesso aberto (Open Access)
Desenvolvimento do processo de síntese da zeólita A e da sodalita a partir de rejeitos de Caulim da Amazônia com aplicações em adsorção
(Universidade Federal do Pará, 2011-08-31) MAIA, Ana Áurea Barreto; POLMANN, Herbert; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607; 7501959623721607
The minimization of industrial and domestic residues is one of the great challenges that human kind is facing. Several proposals are released for this intention, ranging from improving industrial processes in order to minimize waste generation, besides their use in the production of new materials. In this context, this work has the main purpose of using kaolin residues from industries located in the Pará State, northern Brazil, for the production of zeolites (e.g., zeolite A and sodalite). These companies exploit kaolin from the world famous Capim and Jari regions and produce high quality kaolin for the paper industry. Preliminary mineralogical and chemical characterization of the Capim (KC) and Jari (KJ) kaolin residues was carried out as the basis for further zeolite A and sodalite synthesis. The study of thermal activation of kaolinite at various temperatures was carried out using 27Al and 29Si magic angle spinning nuclear magnetic resonance (MAS NMR), in order to to produce highly reactive metakaolinite from KC and KJ residues. The zeolite NaA synthesis was performed for varying parameters such as time and Na/Al relation. Temperature was kept constant at 110 °C for the two starting materials (KC and KJ). The KA, MgA and CaA phases were prepared by ionic exchange from phase NaA. In the sodalite synthesis, kaolinite was used directly as starting material and two temperatures (150 and 200 °C) were utilized. The Na/anion and Na/Al relations were maintained constant and varied, respectively in the reaction mixture for KC and KJ. The removal performance of mixed metal ions (Co2+, Cr3+, Cu2+, Zn2+ e Ni2+) in aqueous solution was investigated by adsorption process on zeolite NaA prepared from KC an KJ as proposal to reduce environmental problem with industrial wastewater streams that contain heavy metals. The XRD results showed that the residues are mainly composed of kaolinite with extremely low impurity level. For comparing the residues from two regions, Capim and Jari verified that the KC displays a high degree of structural order. This difference displays significant influence in the ideal heating temperature to produce a material with high amount of 4-coordinated A1. As a result, the ideal temperature to produce highly reactive metakaolinite is: 600 °C for Jari kaolin residue and 700 °C for Capim kaolin residue. Zeolite A was produced with a large degree of structural order and was generally obtained as the only zeolitic product. The following synthesis conditions were used: Na/Al ratio of 1.64 and time 18 and 20 h for KC and KJ, respectively. The cationic exchange process between Na from zeolite A and K, Mg and Ca in solutions displays efficient result and with XRD data, was verified that the KA, MgA and CaA phases were obtained with success. The sodalite series was produced from KC and KJ and by FTIR was confirmed the chloride, sulphate and carbonate insertion in its structure. The KJ kaolinite displays high reactivated in the sodalite synthesis, it could be explicated by its low degree of structural order. The sorption capacity of heavy metals mixture (Co2+, Cr3+, Cu2+, Zn2+ e Ni2+) on zeolite NaA, produced from KC and KJ, display satisfactory values. The results revealed that the Langmuir model is more appropriate than Freundlich in the fit of the experimental data. Zeolite A, produced from residues (KC and KJ), could be excellent materials for the treatment of wastewater.
Acesso aberto (Open Access)
Dinâmica da paisagem na porção norte da Ilha do Bananal-TO e adjacências ao longo do Quaternário tardio.
(Universidade Federal do Pará, 2019-08-30) MENDES, Laís Aguiar da Silva; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302
Paleoclimatic and paleoenvironmental studies aim to understand processes of global landscapes evolution, contributing to the reconstitution of the quaternary landscapes and the climatic and environmental changes to which were submitted during this period of the earth's geological history. Some studies in the Amazon, but especially those led in regions more sensitive, such as ecotones and wetlands, show that these areas underwent various paleoecological changes during the Pleistocene and Holocene. The present study was led in the Bananal Island region located in a transition area between the Amazon and Cerrado biomes. The Bananal Island, considered by many authors the largest river island in the world, occupies an area of about 20,000 km2 and is located between the middle course of the Araguaia River and its tributary by the right branch, the Javaés River, in the state of Tocantins. The northern portion of the island stands out for its complex mosaic of geomorphological features (marginal dikes, abandoned meanders, paleochannels and lakes) and contrasting geobotanical features (forests and savannas), such that reflect the intense hydrodynamic activity in this region. Seasonally it is flooded by rainwater and rising water table, so it is considered a seasonal wetland. The aim of this work is to understand the dynamics of this landscape, based on the mineralogical and chemical composition of soils and sediments and the palynological composition study of lacustrine sediments of this region. Therefore, samples of ravines exposed on the banks of Javaés and Araguaia rivers, sandy bars and lake sediments were collected. Soils and sediments were analyzed for their mineralogy by X-ray diffraction and chemistry by ICP-AES and ICPMS. The sediment cores collected in 2 distinct lakes, one located in the interior of the northern portion of Bananal Island (Quatro Veados Lake) and the other located on the surroundings of the Javaés River (Mata Verde Lake) were analyzed for their palynological content and dated by AMS 14C. The results of this research are presented in 3 articles: the first one treaties about the mineralogy and geochemistry of the soils and sediments of Bananal Island, the bars and ravines along the Javaés River. Therefore, it discusses about the diversified nature of the minerals and chemical elements that the strata and horizons of these surface covers are composed, pointing to geological provenance, as well as the geochemical processes involved in the current and past dynamics of this landscape. The second article presents the dynamics of vegetation over the last 2000 years AP in the interior of Bananal Island and discusses its relationship with local climatic and edaphic conditions. The third article, on the other hand, describes the vegetational succession occurred in the last 400 years AP, based on the pollen record of sediments from a lake located on the Bananal Island surrounds, and analyzes the modern pollen spectrum in the region. The results obtained through this work present a highly diversified landscape in terms of its geoforms, sedimentary and pedogenetic coverings and geobotanical aspects resulting from the various moments of its geological history and which even today is dynamic and intriguing. The soils and sediments of this landscape are varied as their textures (sequences of sandy and clay materials) and mineralogical and chemical compositions, where primary minerals and derivatives of varied degrees of chemical weathering coexist in the same profile, showing moments of contrasting climatic conditions. Even, nowadays it is possible to observe in situ environments with variable dynamics (erosive, sedimentary, pedogenetic, etc.), as well as, several geochemical processes, such as those of oxidation of sandy bars and ravines and also the reductive processes of these ferruginized sands (sometimes, mistakenly confused for lateritic profiles), due to contact with organic acids produced by forest cover and hydromorphic conditions such as they are subjected. Regarding vegetation changes throughout the late Holocene, climate control was observed, but especially edaphic, since this area is seasonally flooded, a fact favored by the clayey nature of the soil surface horizons, the rainfall high rates as a prolonged rainy season (on average 6 months) and extensively flat terrain. Thus, factors such as flood duration and hydromorphism conditions stemming are responsible for controlling the installation of forests and/or savannas that characterize the region. So, the regency of a drier climate with the shortening rainy seasons that causes the water table rise, may represent favorable conditions for the development and advancement of the forest. On the other hand, a wetter climate with longer rainy seasons would cause flooding, covering larger areas and the soils would remain saturated for longer periods, a fact that undermines the advancement of the forest and allows the maintenance or even expansion of savannas, especially those dominated by grasses over the region. However, as already mentioned, the climatic conditions in this region control the expansion of forest formations, but they are not the only protagonists in this process, since the presence of wetland due to low and flat topography, clay soils, soil and sediment saturation is an effective impediment to the forest installation. Another factor responsible for replacing for gallery forest by savanna’s tree, for example, is the channel abandonment, a fact that is currently observed in the region, where it is possible to tread inside these old river beds, many of these places already enriched with species such as Curatella americana and Byrsonima sp among others. The Bananal Island, which is geologically inserted in the context of the Bananal Basin and is bathed by one of the largest hydrographic basins in the Brazilian territory (Araguaia-Tocantins), sets up as an extremely important landscape for understanding the wetlands dynamics and also from the savanna-forest ecotone areas during the Quaternary, since, it fits in both situations. The northern part of the island where this research was developed still needs studies. However, in general, this research has contributed to understand the functional dynamics of this landscape in face of the region climate and environmental changes, as well as to increase the knowledge about the transition landscapes between the Amazon forest and savannas, such as the paleoenvironmental knowledge is still restricted.
Acesso aberto (Open Access)
Dos minerais aos materiais de arquitetura e processos de degradação: edifícios e ornamentos metálicos dos séculos XIX e XX em Belém do Pará
(Universidade Federal do Pará, 2015-06-16) PALÁCIOS, Flávia Olegário; ANGÉLICA, Rômulo Simões; http://lattes.cnpq.br/7501959623721607
The use of iron in architecture was intensified during the second half of the XVIII century in Europe, and its influence spread over many countries in growth, such as Brazil. Belém (PA) was one of the cites that received the larger amount of building and ornaments imported, especially from England, France, Belgium and Portugal, during the XIX e XX centuries. Currently, Belém holds the largest number of iron architecture heritage remnants in the country. Despite of having great importance in construction techniques, many of these buildings were disassembled and remain on the wait for restoration processes. Also, studies about theses constructions only focus on historical and visual discussion, with no understanding of construction materials, causing empirical restoration processes. The knowledge about these materials is important to the detailed study of historical metal alloys, and different fabrication techniques, as well as weathering action, aiming future restoration processes with scientific bases. The main objective of this research is to understand the historical metals, their diversity in iron architecture and fabrication processes, and also weathering action in iron buildings and ornaments from the XIX and XX centuries in Belém. Thus, the following specific objectives were established: a) physical, chemical and mineralogical characterization of alloys and pathologies; b) identification of different kinds of alloys, in order understand the production types; c) determination of metallurgy evolution imported to the Amazon. The materials chosen for this research came from three different sites, due to their representativeness and diversity of pieces and origin: Mercado de Ferro do Ver-o-Peso building; the former chalet from the State’s Press; and the ornaments from tombs and mausoleums of the Soledade Cemetery. The methods used were Scanning Electron Microscopy (SEM) for physical characterization and punctual chemical analysis; and X-Ray Diffractometry (XRD) for mineralogical analysis. The results were presented in three scientific papers indicating: 1) iron alloys mostly composed by ferrite; 2) textural variations exhibiting four types for the building group: nodular cast iron, gray cast iron type E, wrought iron and gray cast iron type B; 3) three classification of gray cast iron for the ornamental group of diverse origins, among A, B and D; 4) corrosion as main weathering action, and products constituted by goethite and hematite; 4) remnant paint coats, formed by metallic zinc, and its products of alteration represented by zincite and hidrozincite. Through the results of this research it was possible to indicate the evolution of processes in iron architecture production, and enrich this research area with scientific information, as subside for future restorative processes.
Acesso aberto (Open Access)
Efeito do tempo de síntese de zeólita A a partir de caulim amazônico, conformação por extrusão e verificação desta na eficiência de adsorção de NH4 +
(Universidade Federal do Pará, 2015-04-24) SANTOS, Suzianny Cristina Arimatéa; NEVES, Roberto de Freitas; http://lattes.cnpq.br/9559386620588673
Kaolin is widely used in the field of materials (ceramics, pozzolans, fillers and manufacture of paints) as much as the waste and the product received. Currently the most exploited use has been in zeolite synthesis, as it presents the most noble applications. Zeolites are synthesized from silicon and aluminum sources, a fact that justifies the use of kaolin, because it is formed essentially by the clay mineral kaolinite (Al2Si2O5 (OH) 4). In this work we made a kaolin comparison of Grass River region with kaolin mineralogical / chemical and other Amazon kaolin reference to see if you can make it a reference material. The comparison was carried out by size analysis, X-ray diffraction, X-ray fluorescence, scanning electron microscopy, differential thermal analysis and infrared spectroscopy and crystallinity calculations. Moreover, the kaolin of the Rio Capim region was used as a source of silicon and aluminum to obtain the zeolite in order to determine the effect of time on the synthesis. Assays were performed in a time of 30 min, 1 h, 2 h and 24 h applied in these zeolites ammonia adsorption. From the synthesized zeolite was carried out the forming process by extrusion, evaluating various ligands (sodium silicate, bentonite, kaolin and CMC) and firing temperatures (500, 700 and 800 ° C). Later, these were extruded applied also in ammonium adsorption to check its efficiency. It was observed that it is possible to use kaolin Grass River as mineralogical reference material (high degree of structural order) and/or chemical, because it showed performance equal or close to the reference kaolin compared in this work. The zeolite A was synthesized from Amazon kaolin and this presented an excellent silicon and aluminum source. All synthesis times gave zeolite A zeolite in amounts of ~ 600 g. All zeolites showed a high degree of structural view to XRD and SEM. It was also found that synthetic zeolite A in 30 minutes time can be performed without loss in its application, since it presented below only 3% difference in adsorption efficiency compared to 24 h. The shaping by extrusion tests proved promising, 5 out of 10 trials were successful in obtaining granulated with physical strength. However, only the granules containing sodium silicate and CMC as a binder showed a high ammonia adsorption efficiency. With values of ~ 95,5% efficiency in 24 hours of contact.
Acesso aberto (Open Access)
Elementos terras raras, U, Th e elementos potencialmente tóxicos em agroecossistemas com uso de fertilizantes no nordeste do Pará
(Universidade Federal do Pará, 2020-11-30) BRAZ, Anderson Martins de Souza; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302
The Amazon region is the last agricultural frontier in Brazil and the increasing demand for food and renewable energy sources has intensified the pressure on land use. The Pará state is one of the world's largest producers of oil palm and black pepper, being the mesoregion Northeast Paraense responsible for the annual production of 1,634,476 tons of oil palm, 39,577 tons of black pepper and 286,768 tons of oranges, which represents 97, 50 and 2% of the Brazilian production. The Amazon soils, to express the high agricultural potential, demand high rates of fertilizer application. However, the raw materials used in the production of agricultural inputs are also sources of soil contamination. Thus, studies that facilitate the understanding of the dynamics of rare earth elements (REEs) and other metals / metalloids in the region's soils are relevant. And, based on the premise that anthropic action, mainly through agricultural activities, has caused significant increases in the levels of these elements in soils, the objective was to evaluate (i) the REEs concentrations and other metals in Amazon agroecosystems of orange, oil palm and black pepper, with 26, 10 and 5 years of implantation, respectively; (ii) determine the contamination rates, such as the enrichment and bioaccumulation factors and; (iii) establishing / discussing relationships with soil properties. The results showed: (i) REEs are extremely correlated to soil pH; (ii) the europium (Eu) presented the largest bioaccumulation factor among the REEs; (iii) the activity concentrations of 238U and 232Th in soil with black pepper cultivation were higher than the world average of 238U (35 Bq kg-1) and 232Th (30 Bq kg-1) according established by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR); (iv) moderate enrichment factors (EFs) for Ba, Pb and Zn (2> EF <5) and significant for As and Cu (5> EF <20); (v) the following orders of bioaccumulation: oil palm - Cu> Zn> Hg> Ni> Ba> Co> As> Cr> Cd ≈ Pb; black pepper - Zn> Hg> Cu> Ba> Ni> Co> Pb >> As> Cr> Cd; orange - Hg> Ni> Ba> Zn> Co> Cu> As> Pb >> Cr> Cd. In this context, this is the first study evaluating the absorption of REEs by Amazonian crops of great importance for global markets. A relevant contribution to predict the accumulation of contaminants in soils resulting from anthropic activities, especially in regions of agricultural importance and environmental vulnerability such as the biome Amazon.
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/8489178778254136
The 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.
Acesso aberto (Open Access)
Estudos isotópicos de U-Pb, Lu–Hf e δ18o em zircão: implicações para a petrogênese dos granitos tipo-A paleoproterozóicos da província Carajás – Cráton Amazônico
(Universidade Federal do Pará, 2018-04-05) TEIXEIRA, Mayara Fraeda Barbosa; SANTOS, João Orestes Schneider; http://lattes.cnpq.br/5516771589110657; DALL'AGNOL, Roberto; http://lattes.cnpq.br/2158196443144675
In ca. 1880 Ma an extensive magmatic event generated A-type granites with rapakivi affinity in the Amazonian Craton, especially in the Carajás Province. In this Province these granites are grouped into three main suites according to mineralogy, geochemistry, and state of oxidation of their magmas – Jamon, Velho Guilherme, and Serra dos Carajás – and include also the Gogó da Onça, Seringa, São João, Gradaús, and Rio Branco plutons. The Gogó da Onça Granite (GOG) comprise a stock composed by biotite-amphibole granodiorite, biotiteamphibole monzogranite and amphibole-biotite syenogranite. The GGO crosscut discordantly the Archean country rocks and are not foliated. All Gogó da Onça Granite varieties are metaluminous, ferroan A2-subtype granites with reduced character. The major and trace element behavior suggests that its different facies are related by fractional crystallization. Zircon and titanite U–Pb SHRIMP ages show that the pluton crystallized at ~1880-1870 Ma. This is more akin to the Serra dos Carajás Suite and to the Seringa and São João granites of Carajás and to the Mesoproterozoic Sherman granite of USA and the Paleoproterozoic Suomenniemi Batholith of Finland. New U-Pb SHRIMP data for the Serra dos Carajás, Velho Guilherme and Jamon Suite and for Seringa and São João Granite show that these plutons crystallized between 1880 Ma to 1857 Ma. Some granites of the Velho Guilherme and Jamon suites and of the Seringa Granite presented 1920 to 1900 m. y. old zircon and titanite crystals interpreted here as antecrysts from an earlier pulse of magma that were incorporated in the main later pulse of 1880 Ma. We also obtained ages of 1865 Ma to 1857 Ma in the leucogranite facies of the Redenção and Bannach plutons, which indicate that the leucogranites of these plutons are younger than their ~1880 Ma old granites and were generated by independent magma pulses that are not cogenetic with the less evolved facies of the respective plutons. Besides it, an age of 1732 ± 6 Ma obtained in the leucogranite facies of the Antônio Vicente pluton of the Velho Guilherme Suite that could represent a magmatic event in the Xingu Region not yet reported or, eventually, could correspond to an isolate hydrothermal event that allowed the growth of zircons. This ranites have been also analysed by Lu–Hf and Oxygen isotopes and few granites also by Nd isotopes. Zircons from all the granites have remarkably restricted initial 176Hf/177Hf (0.281156 and 0.281384) and strongly negative εHf(t) values ranging from –9 to -18, and δ18O fairly homogeneous varying from 5.50‰ to 7.00‰. Small differences were observed internally in the plutons or between them. The ƐHf(t) values of the analysed plutons are strongly negative and similar to Nd isotopic data. The Serra dos Carajás Suite has ƐHf(t) values of -14 to -15.5, the Jamon Suite of -9.5 to -15 and values of -12 to -15 for the Velho Guilherme Suite, while São João, Seringa and Gogó da Onça granites have stronger negative values (ƐHf(t)= -12 to -18). Crustal model ages indicate a Paleoarchean source (3.3 Ga to 3.6 Ga) with a minor contribution from Mesoarchean (3.0 Ga to 3.2 Ga) melts for these granites. This model ages are older than the exposed Archean country rocks of the Orosirian granites of the Carajás Province and more investigation is needed to verify the real existence of that older Archean crust. The studied samples have Hf– O isotopic compositions that overlap within error, and evidence of contamination (crustal assimilation or mixing) of a mantle-derived magma cannot be seen. These plutons crystallized from magmas generated by melting of pre-existing igneous rocks with possibly in the Velho Guilherme Suite a minor contribution from a supracrustal (metasedimentary) component. The Nd, Hf, and O isotope compositions of the Paleoproterozoic granites of Carajás Province clearly attest to an igneous ancient crustal source in the origin of their magmas. The differences observed can result for contrasts in the crustal domains of the Carajás Province that were the source of the granites or of local contamination processes.
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/0000-0003-0854-3053
The 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.
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A Evolução da paisagem de transição savana-floresta em Roraima durante o Holoceno tardio: base mineralógica, geoquímica e palinológica
(Universidade Federal do Pará, 2011-01-10) MENESES, Maria Ecilene Nunes da Silva; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302; https://orcid.org/0000-0002-0134-0432
The Amazonia includes several vegetation physiognomies, besides the large and well-known tropical forest. The savannas, for instance, are present in several areas as discontinuous patches or covering extensive areas as it is the case of the savannas found in the north and northeast portions of the Roraima state. These savannas belong to the so-called Rio Branco-Rupununi Complex considered the largest continuous block of that vegetation type in the Brazilian Amazonian which in the state of Roraima covers about 41.000 km2 of a total of 53.000 km2 being limited to the south and west by tropical forests. In order to understand the vegetational dynamic and the evolution of the whole landscape in face of the possible climatic changes occurred along the geological time, the present study was carried out. The chosen area for this work represents a zone of transition between savannas and forests in the western portion of the savanna block, where four topossequences (FC, FH, TIA and RU) representative of the relief, vegetation and pedological cover patterns were selected for sampling. Then, samples of the regolith cover were collected starting at the base of the topossequences (veredas) until their top parts following the visible texture and color variations of the materials. Additionally, other two veredas (AM and MB) were also cored. These regoliths samples were submitted to analyses such as granulometrical by wet sieving; mineralogical by XRD and chemical (major and trace elements) by ICP-MS and XRF methods. The sediments of the veredas were still dated by radiocarbon method using the AMS (Accelerator Mass Spectrometry) technique, and also submitted to palynological analyses including the counting of charred particles. The regoliths of the studied area vary of sandy to silty sand textures being composed by quartz and kaolinite, and in minor amounts by muscovite, sillimanite, goethite, microcline and albite. The high values of SiO2 confirm the quartzose character of these regoliths, while the values of Al2O3, more expressive in the saprolite and in the sediments from veredas reflect the higher participation of the kaolinite, which is the single clay mineral identified in these samples. The mineralogical and chemical compositions of these materials indicate provenience of metamorphic rocks and laterites that faced with warm and wet climatic conditions have been suffered strong chemical weathering and leaching. The formation and wide development of vereda of Mauritia flexuosa since about 1550 years BP as showed by the pollen analyses corroborate the humidity increase in the area, which also favored the expansion of forests. In fact, trees of Virola, Alchornea, Melastomataceae and Moraceae among other were frequent suggesting that gallery forests as well as patches of secondary forests indicated by Didymopanax, Cecropia and Attalea occurred in this region in the most of the recorded period. In spite of those humid conditions, there are records of reduction of the forests about 1400-1100 years ( FC), 900-200 years (AM and FC) and between 700 and 300 years (site TIA) in favor of the expansion of the savannas. It is probable that the reduction of forests during those periods has been provoked by the increase in the intensity of fires, inferred by the highest concentration of charred particles in the sediments, prior and during the forest cover decrease. These fires are still common in the area, being more frequent in the neighborhoods of human establishments (indigenous) and cattle farms where they possibly work as a barrier to forest expansion. Although, alternate hydromorphic and hydrological stress conditions also contribute to prevent a forest expansion. The granulometrical, mineralogical and geochemical characteristics of the regolith cover combined to the sediments pollen and ages records allowed to interpret that the studied savanna-forest landscape, which is currently marked by a complex mosaic of grassy and woody savanna crossed by veredas of Mauritia flexuosa, gallery forest corridors and islands of forest covering sandy, quartzose and kaolinitic regoliths agree with the modern warm and wet climate conditions prevailing in this region since the Late Holocene. In compensation, features such as stone lines composed by fragments of quartz and crusts denote erosive events occurred probably in the Late Pleistocene and even in the Medium Holocene when dry to arid climates dominated the region. Then, the regarded landscape has been a stage of intense ecological and geomorphological transformations fomented mainly by the climatic changes imposed to the area, although the prehistoric and the modern man has also contributed, in the sense of delaying the expansion of the forests on the savannas.
Acesso aberto (Open Access)
Evolução supergênica do depósito cuprífero Alvo 118 - Província Mineral de Carajás
(Universidade Federal do Pará, 2022-12-15) SANTOS, Pabllo Henrique Costa dos; COSTA, Marcondes Lima da; http://lattes.cnpq.br/1639498384851302; https://orcid.org/0000-0002-0134-0432
The Carajás Mineral Province is home to one of the most extensive cupriferous belts in the world, where hypogene mineralizations were partially transformed into gossans, later lateritized and/or truncated during landscape evolution. These covers represent an information source for mineral exploration and, in some cases, can be mined together with parental hypogene mineralizations. The plateaus of the South American Surface host complete and lateritized gossans, while the surrounding denuded areas, typical of the Velhas Surface, exhibit incomplete or immature gossans, with the Alvo 118 deposit as an example. In this orebody, the hypogene mineralization was converted into an immature gossan located at depth, while the host rocks were weathered near the surface, forming a mineralized saprolite. The gossan comprises an oxidation zone, which includes goethite, malachite, pseudomalachite, cuprite, tenorite, native copper, ramsbeckite, chrysocolla, and libethenite, with relics of a secondary sulfide zone, represented by chalcocite. These minerals are distributed in the goethite, malachite, cuprite, and libethenite zones, with their mineral successions reflecting the transition of mineralizing solutions from acidic to slightly alkaline conditions and an increase in oxidation potential. This environment was established from the interaction of acid solutions, derived from chalcopyrite dissolution, with the gangue minerals (calcite and apatite) and the host rocks, granodiorites and, secondarily, chloritites, which acted in buffering the system, favoring the formation of new copper-bearing minerals. The strong correlations of CuO with Ag, Te, Pb, Se, Bi, Au, In, Y, U, and Sn in the hypogene mineralization reflect the inclusions of petzite, altaite, galena, uraninite, cassiterite, and stannite in chalcopyrite. In the gossan, Ag, Te, Pb, Se, and Bi remained associated and were incorporated into neoformed copper minerals. On the other hand, Au, In, Y, U, and Sn exhibit greater affinity with iron oxyhydroxides, as well as Zn, As, Be, Ga, Mo and Ni. The δ65Cu values reinforce that the investigated gossan is immature and was not intensely affected by leaching processes. The main mineral phases identified in the saprolite are kaolinite (predominant), associated with chlorite, smectite, vermiculite, quartz, and iron oxyhydroxides. Iron oxyhydroxides are strongly correlated with Ga, Sc, Sn, V, Mn, Co, and Cr, partly derived from the weathering of parent rocks. Additionally, Mössbauer spectroscopy data point to the important role of ferrihydrite and goethite as copper-bearing phases. There is no evidence of copper incorporation by clay minerals. The δ56Fe values indicate a little contribution of primary mineralization to the Fe content of the saprolite, which is more influenced by chlorite weathering. The association Al2O3, Hf, Zr, Th, TiO2, Ce, La, Ba, and Sr represents the geochemical signature of the host rocks, which influence the chemical composition of the three types of mineralization. On the other hand, the association In, Y, Te, Pb, Bi, and Se comprise the main pathfinder elements of the hypogene mineralization. Detailed knowledge of the supergene mineral and geochemical fractionation makes the Alvo 118 deposit a reference guide for investigating immature gossans and mineralized saprolites in denuded areas of the Carajás Mineral Province or equivalent terrains.
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/0000-0001-7976-0472
The 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.