Dissertações em Geologia e Geoquímica (Mestrado) - PPGG/IG
URI Permanente para esta coleçãohttps://repositorio.ufpa.br/handle/2011/2604
O Mestrado 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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Item Acesso aberto (Open Access) Distribuição geoquímica dos metais no material particulado em suspensão - MPS na margem direita da Baia de Marajó, Costa Amazônica, Brasil(Universidade Federal do Pará, 2025-03-25) ANDRADE, Robinson da Cruz; KUTTER, Vinicius; http://lattes.cnpq.br/6652786694334612; https://orcid.org/0000-0001-7295-6800The Marajó Bay, located in the Amazon region, is one of the largest estuarine systems in Brazil. It is influenced by the Amazon and Tocantins Rivers, with intense hydrodynamics and physico-chemical processes that affect metal distribution. This study aimed to analyze the concentrations and distribution of the elements Al, Fe, Mn, Mg, Zn, Cr, V, Ti, and Ca in suspended particulate matter (SPM) from the right margin of Marajó Bay, correlating the results with environmental factors such as salinity, pH, and local hydrodynamics. Samples were collected at three strategic points— Icoaraci (Point 1), Mosqueiro Island (Point 2), and Colares (Point 3) — during two campaigns carried out between April and May 2023. A Van Dorn bottle was used for surface and 20-meter depth sampling, covering the complete tidal cycle. The particulate material was filtered using cellulose acetate filters (0.45 μm) and analyzed by X-ray fluorescence spectrometry for quantitative determination of the elements. Physico-chemical data such as temperature, pH, salinity, and Eh were obtained using multiparameter probes, and current data using ADCP. Statistical analysis included Kruskal-Wallis tests, Pearson correlations, and boxplots. The results revealed significant variations in SPM concentrations among the sampling points. At Point 3 (Colares), the highest concentrations were observed at the surface (0.278 mg/L), indicating lower hydrodynamic energy and greater deposition of fine sediments, favored by saline intrusion and metal flocculation. Point 1 (Icoaraci) showed the lowest concentrations, suggesting higher sediment removal due to tidal dynamics and river discharge. The Kruskal-Wallis test indicated significant differences among surface samples, especially for Mg, Al, Ti, V, Cr, Fe, and Zn. At depth, only Mg and Zn showed significant variations. Pearson correlations revealed strong associations between Fe, Cr, Mn, and Zn at Point 3, suggesting co-transport of these metals, likely governed by adsorption onto iron and manganese oxides, particularly under low-energy conditions. The observed geochemical behavior highlights that hydrodynamics and saline intrusion are key factors controlling the spatial and vertical distribution of metals in Marajó Bay. It is concluded that Marajó Bay is a highly dynamic estuarine environment, where the deposition and transport of metals in SPM are controlled by both physical processes, such as hydrodynamic variation, and chemical processes, such as flocculation in saline environments. The findings contribute to the understanding of geochemical processes in the Amazon region and provide valuable insights for environmental management and the preservation of local ecosystems.Item Acesso aberto (Open Access) Assinatura geoquímica do ouro na Província Mineral do Tapajós, Cráton Amazônico: o exemplo dos depósitos São Jorge e São Chico(Universidade Federal do Pará, 2025-06-19) GOMES, Iolanda Clara do Carmo; LIMA, Rafael Guimarães Corrêa; http://lattes.cnpq.br/6751523860876497; LAMARÃO, Claudio Nery; http://lattes.cnpq.br/6973820663339281; https://orcid.org/0000-0002-0672-3977Gold has a great economic importance, and the determination of its geochemical and isotopic signatures, exploited in Brazil’s main mineral provinces, has become a valuable tool not only for mineral exploration but also for tracing its origin and circulation. The aim of this study is to characterize and compare the chemical composition of gold from two different deposits using scanning electron microscopy paired with energy-dispersive spectrometry (SEM‑EDS), to evaluate the viability in differentiating provenance on local and regional scales, and to discuss the factors controlling element distribution in native gold. São Jorge and São Chico are gold deposits located in the eastern portion of Tapajos Mineral Province, aligned along the Tocantinzinho lineament (WNW‑ESE). The gold mineralization at São Jorge deposit consists of a paragenesis formed by gold + pyrite + chalcopyrite ± sphalerite and, rarely, galena, which host two generations of gold with distinct chemical compositions. These gold phases occur either in quartz veins and/or in sulfide disseminations in strongly hydrothermally altered host rocks. In this deposit, gold is mainly hosted by pyrite, occurring in the form of inclusions with high Au contents (84.27–91.02 wt%) and filling pyrite fractures with a composition richer in Ag (7.86–15.72 wt%). The geochemical and textural differences indicate at least two distinct mineralizing events. In contrast, the São Chico deposit shows a paragenesis formed by gold + pyrite + galena + sphalerite ± chalcopyrite, in which gold occurs as electrum within polymetallic sulfide‑bearing quartz vein systems. Here, gold is mainly hosted by galena, and textural relationships between these two minerals suggest simultaneous precipitation under low‑temperature conditions. Gold in this deposit also occurs with chalcopyrite and sphalerite, as reflected in its chemical composition, which shows higher average of Cu (0.44 wt%) and Zn (0.42wt%) contents, respectively. Principal component analysis (PCA) identified Ag, Fe, and Te as the elements with the greatest potential for gold discrimination between these two deposits. Gold microparticles from the São Jorge deposit exhibits a geochemical signature with higher contents of Au (73.82–91.02 wt%), Fe (0.54–6.21 wt%), and Te (0.37–3.61 wt%), compared to gold from the São Chico deposit, which displays higher concentrations of Ag (29.82–51.42 wt%).Item Acesso aberto (Open Access) Gênese e distribuição estratigráfica das concreções carbonáticas da ilha de Baunilha Grande, região do Quatipuru - Pará(Universidade Federal do Pará, 2025-06-27) GARCIA, Danilo Sena; SOARES, Joelson Lima; http://lattes.cnpq.br/1345968080357131In the Baunilha Grande Ecofacies, defined by Petri (1957) and located on Baunilha Grande Island, in the Quatipuru region, Pará, carbonate concretions known as carcinolites are found. However, near these carcinolites, there are other concretions whose origin and stratigraphic position had not yet been described. These concretions are part of the Pirabas Formation, from the Lower Miocene, composed of fossiliferous limestones and sedimentary deposits that record a shallow coastal marine environment influenced by tides. This study aims to characterize the formation of carbonate concretions on Baunilha Grande Island and their relationship with the diagenetic and stratigraphic processes of the Pirabas Formation. The methodology included: (I) Petrographic, mineralogical, and geochemical analysis of the concretions, using techniques such as optical microscopy, X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Energy Dispersive Spectroscopy (EDS); (II) Stratigraphic correlation of the concretions with similar deposits in Salinópolis and Maracanã, relating them to sedimentation events, bioturbation, and diagenesis. The results indicate that the concretions exhibit different shapes and compositions, classified into four main types: spherical, tubular, rough, and bulbous. Mineralogical analysis revealed the predominant presence of quartz and calcite, along with kaolinite and kutnohorite in some samples. Pyrite is present in all concretions, particularly associated with organic fossils and the diagenesis of diatoms. The presence of these concretions suggests early cementation processes in sandstone lenses and bioturbation in shales, influenced by sea-level variations and storm events. The high pyrite content in the concretions indicates a reducing depositional environment favorable for organic matter preservation and sulfide formation. The relationship between concretions and sedimentary structures suggests that these features are restricted to the top of the Pirabas Formation, near its contact with the Barreiras Formation. Thus, the occurrence of these concretions can serve as a stratigraphic marker for the top of the Pirabas Formation.Item Acesso aberto (Open Access) Análise palaeoambiental e caracterização dos Folhelhos Negros da Formação Barreirinha utilizando análises Multiproxy(Universidade Federal do Pará, 2025-06-04) CARVALHO, Wivian Maria Rodrigues; BRITO, Ailton da Silva; http://lattes.cnpq.br/9873489431846769; HTTPS://ORCID.ORG/0000-0001-9224-5563; SOARES, Joelson Lima; http://lattes.cnpq.br/1345968080357131The initial sedimentation phase of the Barreirinha Formation was associated with a rapid relative sea-level rise during a significant marine transgression event that flooded the Amazon Basin. These organic-rich shales outcrop along a narrow yet extensive belt located on the southern margin of the Amazon Basin. Few studies have specifically addressed the potential paleoenvironmental variations linked to the deposition of these shales. This is mainly due to the relative lithological uniformity of these rocks—composed predominantly of fine-grained sediments—and their economic relevance, which has directed most research toward the maturation of organic matter. To investigate the paleoenvironmental variations during the deposition of these fine sediments—focusing on sedimentary dynamics, the origin, and provenance of the organic matter—a multiproxy approach was applied, combining various quantitative, semi-quantitative, and qualitative techniques. The analyzed stratigraphic succession is mainly composed of gray to black shales, exhibiting facies variations related to coarse terrigenous input and episodes of bioturbation. These features suggest a deep, distal, anoxic marine depositional environment, with no evidence of carbonate sedimentation, typical of the Abacaxis Member of the Barreirinha Formation. Mineralogical cluster analyses indicate a dominance of kaolinite, characterizing the Kaolinite Facies, with subordinate quartz, sulfates, and sulfides in the lower portions. The base of the succession includes massive fine-grained sandstones with cross-bedding, correlated with the Ereré Formation, interpreted as deltaic to inner shelf deposits. The transition to laminated shales interbedded with sandstones and siltstones marks the onset of the Devonian (Frasnian) transgression, with substantial continental input evidenced by heavy minerals, pyritized plant remains, and tasmanites. The presence of dumpstones suggests glacial influence and ice-rafted debris deposition. Upper levels show more homogeneous shales, enriched in organic matter, lacking bioturbation and detrital minerals, indicating maximum anoxia during the peak of the transgressive event in the Amazon Basin. Diagenetically, the shales underwent compaction, fracturing, mineral substitution, oxidation, and intense pyritization, mainly as framboidal pyrite—typical of reducing marine environments. The mineralogy is dominated by kaolinite and quartz, with accessory minerals indicating alteration processes and possible Jurassic-Triassic igneous intrusions (Penatecaua magmatism), which contributed to increasing the thermal maturity of the kerogen. Rock-Eval pyrolysis and biomarker analyses reveal Type II-III kerogen with gas-generating potential, ranging from immature to post-mature depending on proximity to igneous intrusions. These findings reflect a transgressive system strongly influenced by environmental controls and regional thermal input.Item Acesso aberto (Open Access) Petrografia e mineralogia das alterações hidrotermais associadas ao bloco Sul do depósito aurífero Volta Grande do Xingu, Domínio Bacajá (PA), Cráton Amazônico(Universidade Federal do Pará, 2025-04-22) PINTO, BRENDA THAYS BARROS; FERNADES, Carlos Marcello Dias; http://lattes.cnpq.br/0614680098407362; https://orcid.org/0000-0001-5799-2694The world-class Volta Grande gold deposit, at the Bacajá Domain, contains measured reserves of approximately 6.0 Moz at 1.02 g/t, divided into the north and south exploratory blocks. Historically, this mineralization has been classified as orogenic (lode-type) and is found within a set of mylonitized granitoids in the amphibolite facies of medium to high metamorphic degree attributed to the Três Palmeiras Group (2.41 Ga) and the Oca Granodiorite (2.16 Ga). However, recent research on the rocks of the northern block has established a late volcanic sequence with significant gold mineralization. Aiming to contribute to its metallogenetic modeling, this Master’s Dissertation focused on the southern block, involving macroscopic and microscopic petrographic descriptions and the application of VNIR–SWIR reflectance spectroscopy in core samples from the Pequi, Grande, and Itatá targets. First, the results include the petrography of metamorphic rocks, represented by amphibolite and mylonitic granodiorite, and an associated isotropic volcanic and plutonic suite. The data compilation revealed mineral paragenesis related to metamorphic and magmatic-hydrothermal processes. The metamorphic paragenesis reveals regional and dynamic-thermal metamorphisms and moderate overprinting of hydrothermal alterations typical of epithermal systems, associated with the emplacement of the isotropic rocks package. Second, in the isotropic rocks, there is an overprint of hydrothermal alterations and gold mineralization conceivably of intermediate- and high-sulfidation epithermal-type genetically linked to magmatic-hydrothermal systems, with carbonate alteration in a boiling zone and advanced argillic alteration. In conclusion, data integration from the southern block shows, similarly to the northern block, at least two genetically distinct gold mineralizing events that enhanced the grade and tonnage of the Volta Grande deposit, thus representing a new prospective model for the Bacajá Domain.Item Acesso aberto (Open Access) Mapeamento geoquímico de baixa densidade por sedimentos de corrente em Roraima: definição de valores de referência (background/baseline geoquímico) e abordagens por índices ambientais e análise multivariada(Universidade Federal do Pará, 2025-01-17) GALINDO BARÓN, Andrés Fernando; MARQUES, Eduardo Duarte; http://lattes.cnpq.br/8256609331887637; HTTPS://ORCID.ORG/0000-0003-1133-9408; KUTTER, Vinicius Tavares; http://lattes.cnpq.br/6652786694334612; https://orcid.org/0000-0001-7295-6800Stream sediments provide essential information on the distribution of chemical elements in river basins, whether because of rock weathering or the influence of human activities. In the State of Roraima, growing concerns about the impacts of mining and agriculture drive the need to define a geochemical baseline. This baseline allows distinguishing natural element concentrations from those influenced by anthropogenic activities. Such an analysis is crucial for accurately assessing environmental impacts and monitoring future changes in regional geochemistry, in accordance with the elements stipulated in CONAMA Resolution 454/2012 (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn). For this purpose, data from the "Low-Density Geochemical Survey in the State of Roraima" project were used, with samples collected between 2009 and 2013. Sampling was carried out synchronously during the same precipitation period to avoid errors due to seasonality. The study area covers 106,369.051 km², distributed across 429 micro-basins. Active stream sediments were collected by the SGB following the technical manual of the Geochemistry Area v.5.0. At each sampling site, coordinates were recorded, and the material was sieved to obtain the silt and clay fraction. The samples were collected in a composite manner over an approximately 100-meter stretch along the drainage upstream of the access point. The analytical methods protocol included drying the samples at 60°C, sieving them through a <80-mesh screen, and sending them to the SGS GEOSOL LTDA laboratory for chemical analysis. In the laboratory, the samples underwent digestion with aqua regia (HNO₃ + 3HCl) and were subsequently analyzed for 53 chemical elements (Ag, Al, As, Au, B, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cs, Cu, F, Fe, Ga, Ge, Hf, Hg, In, K, La, Li, Mg, Mn, Mo, Na, Nb, Ni, P, Pb, Pd, Pt, Rb, Re, S, Sb, Sc, Se, Sn, Sr, Ta, Te, Th, Ti, U, V, W, Y, Zn, and Zr) using ICP-OES and ICP-MS. Exploratory data analysis employed descriptive statistics, graphs, and contingency tables to support the selection of non-parametric univariate, bivariate, and multivariate statistical techniques. Additionally, modern methods were applied to determine geochemical baseline values, including mMAD, TIF, and percentiles (98, 95, 90, 75). Anomalies identified in the singleelement maps, based on the geochemical baseline thresholds, are explained by multielement associations determined through confirmatory factor analysis. This analysis revealed six main associations that explain the distribution of chemical elements and their relationship with various geological processes. Factor 1 (20.60% of variance): Includes elements such as Ba, Cs, Rb, Sr, and Zn, associated with differentiated igneous rocks, granites, pegmatites, and hydrothermal processes linked to the Surumu domain. Factor 2 (15.76%) Highlights rare earth elements and actinides (Ce, La, Th, U, Y), concentrated in accessory minerals such as monazite and apatite, associated with the magmatism of the Orocaima Igneous Belt. Factor 3 (13.90%) Identifies an association of Mn, Nb, Ti, and Fe with tholeiitic magmatism in the Avanavero Suite and alluvial deposits. Factor 4 (11.68%) Comprises elements typical of mafic and ultramafic rocks, such as Co, Cr, Cu, Ni, and V, present in Mesoproterozoic basalts and gabbros. Factor 5 (7.51%) Relates elements like Al, Ga, Pb, and Zn to weathering processes and the formation of secondary minerals in saprolitic and alluvial environments. Factor 6 (6.01%) Associates Sc, Sn, and Nb with granite intrusions and placer deposits related to the magmatism and tectonics of the Uatumã SLIP and the Orocaima Igneous Belt. The environmental quality assessment using geochemical and environmental indices indicated that the region exhibits significant enrichment, mainly related to geology. The interpretation of results highlights the interaction between regional geology and tectono-magmatic processes in the distribution of analyzed elements. Additionally, anomalous zones with potential for targeted investigations were identified, particularly in areas impacted by human activities and land-use changes.Item Acesso aberto (Open Access) Mapeamento geoquímico por sedimentos de corrente da bacia hidrográfica do Rio Capim-Pa: definição de valores de baseline geoquímico e aplicação de índices ambientais(Universidade Federal do Pará, 2025-01-16) SERRA, Julio Richard Furtado; MARQUES, Eduardo Duarte; http://lattes.cnpq.br/8256609331887637; HTTPS://ORCID.ORG/0000-0003-1133-9408; KÜTTER, Vinicius Tavares; http://lattes.cnpq.br/6652786694334612; https://orcid.org/0000-0001-7295-6800Geochemical mapping plays a key role in both mineral prospecting and environmental studies. Initially used to identify geochemical anomalies associated with mineral deposits, these studies have gained relevance in the field of environmental geochemistry, enabling the monitoring of soil, water, and sediment quality. The Geological Survey of Brazil (SGB) conducts geochemical survey projects across the national territory. One such project, carried out between 2009 and 2012, called "Multi-use Geochemistry," covered the Capim River Watershed (CRW) area and generated a geochemical sediment dataset for the region. The objective of this research was to use this available data to create multielemental geochemical maps and define baseline geochemical values, particularly for potentially toxic elements. The survey included the collection of 276 stream sediment samples with a sampling density of approximately one sample every 150 km². The samples were processed in the laboratory for analysis by ICP-OES and ICP-MS with hydride generation for Hg. In total, 52 elements were analyzed (Ag, Al, As, Au, B, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cs, Cu, Fe, Ga, Ge, Hf, Hg, In, K, La, Li, Mg, Mn, Mo, Na, Nb, Ni, P, Pd, Pb, Pt, Rb, Re, S, Sb, Sc, Se, Sn, Sr, Ta, Te, Th, Ti, U, V, W, Y, Zn, and Zr). For statistical treatment, statistical summaries were calculated along with box plots, histograms, and normal probability curves using log-transformed data for univariate statistics; Spearman correlation for bivariate statistics; and factor analysis (FA) to define multielemental associations in multivariate statistics. Three methods were applied to calculate the geochemical baseline (BG), including the Median ± 2*Median Absolute Deviation (mMAD), Tukey's Inner Fence (TIF), and Percentiles (98, 95, 90, 75). The results revealed important geochemical distribution trends, with a particular focus on potentially toxic elements. In total, 28 elements (Ag, Al, Ba, Bi, Ce, Co, Cr, Cu, Fe, Ga, Hf, Hg, La, Mo, Nb, Ni, Pb, Rb, Sc, Sn, Sr, Th, Ti, U, V, Y, Zn, and Zr) underwent more complex statistical tests, while 24 elements were not tested due to ≥30% of the data being below the detection limit. Correlation analyses showed that there were 7 correlations with significance values greater than 0.65 and 6 acceptable correlations with values between 0.575 and 0.65. It was observed that Cr levels exceeded the values stipulated by the resolution in all three methods analyzed: TIF (73.11 mg.kg⁻¹), mMAD (46.76 mg.kg⁻¹), and 98th Percentile (43.00 mg.kg⁻¹). In the lithological unit analysis, Cr anomalies were most pronounced for the siliciclastic rocks of the Barreiras Formation, with TIF (182.94 mg.kg⁻¹), mMAD (90.88 mg.kg⁻¹), and Percentiles 98th (66.28 mg.kg⁻¹), 95th (62.20 mg.kg⁻¹), 90th (52.60 mg.kg⁻¹), and 75th (40.52 mg.kg⁻¹), as well as in Lateritic Covers with TIF (81.76 mg.kg⁻¹) and mMAD (46.49 mg.kg⁻¹). The mMAD method was considered the most conservative and robust, without overestimating the upper limit values. Factor analysis allowed the identification of 7 factors, and along with the spatial mapping of the scores, it was possible to identify the geochemical associations, which primarily reflect the geological influence in these sediments, with lateritic terrains, iron oxyhydroxides, and aluminossilicatic clastic rocks being the main factors responsible for the distribution of the elements. Geochemical and environmental indices were calculated, such as the Enrichment Factor, Contamination Factor, Modified Contamination Degree, and Potential Ecological Risk Index. These indices indicated that, in several microbasins, there are signs of geological sources, but they mainly point to the northern, western, and southwestern areas of the CRW as the most contaminated. These approaches enabled the identification of contaminated areas, especially related to Cr, Cu, Hg, Ni, and Pb, whose concentrations exceeded the limits established by CONAMA Resolution 454/2012 at several points in the basin. However, it is worth noting that the normative uses reference values for total sediment, and the results of the present work are overestimated compared to this standard. Nevertheless, the use of environmental indices must be done with caution, as there are limitations that, when analyzed in isolation, may provide information not entirely aligned with local reality, either overestimating or underestimating data. It is important to highlight that, despite presenting higher concentrations of these elements, the values found are still lower than those found in geochemical provinces with mineralizations. This indicates a strong influence of superficial geochemical processes in the adsorption of Cr, Cu, Ni, and other potentially toxic metals in iron oxyhydroxides. Furthermore, the study reaffirms the use of the mMAD method as the most robust and suitable for defining baselines and the use of geochemical distribution maps as an essential tool for territorial management.Item Acesso aberto (Open Access) Morfologia e composição de rutilo como guia prospectivo para depósitos de Au: o exemplo do depósito São Jorge, Província Mineral do Tapajós(Universidade Federal do Pará, 2025-03-18) MEDEIROS, Marcos Flávio Costa; LAMARÃO, Claudio Nery; http://lattes.cnpq.br/6973820663339281; https://orcid.org/0000-0002-0672-3977The Tapajós Mineral Province (PMT), inserted in the context of the Tapajós-Parima or Ventuari-Tapajós geochronological province, is recognized as the largest gold-bearing province in Brazil. The São Jorge Jovem Granite (GSJJ), located east of the PMT in a heavily fractured and hydrothermalized area, hosts gold mineralization. The GSJJ exhibits calcium-alkaline affiliation K-rich, composed of rocks of monzogranitic and leucomonzogranitic composition, with amphibole and biotite as the main mafic minerals. Pb-Pb dating of zircon in leucomonzogranites revealed a crystallization age of 1891±3 Ma. TiO2 polymorphs are common accessory phases in several types of rocks. In nature, it occurs in three main polymorphs: anatase and brookite, which are representatives of low temperatures and pressures, and rutile, at medium to high and ultra-high pressures and temperatures. Of these, rutile is the most common polymorph in the Earth's crust. The samples and polished blades used in this research come from drilling holes carried out by Rio Tinto Desenvolvimento Minerais (RTZ) in GSJJ. TiO2 polymorphs are represented by thin (10-100μm) anhedral crystals in or surrounding biotite. Samples from the mineralized zone show varied hydrothermal alteration, with rocks in the propylitic and phyllic alteration stages. TiO2 polymorphs form acicular aggregates or aggregates with a skeletal texture, predominantly replacing titanite. Spot electron microprobe analyses conducted on individual crystals and aggregates of rutile crystals revealed significant compositional variations, particularly concerning the contents of Nb, Al, Zr, V, and W. Rutile crystals from the non-mineralized zone (NMZ) exhibited higher levels of Nb (> 5,000 ppm) compared to crystals from the mineralized zone (MZ; predominantly < 3,000 ppm). Rutile crystals from the MZ display a trend of Al enrichment and V. Crystals from the NMZ sometimes show enrichment in Fe but are always accompanied by levels considered to be Nb. ZM crystals exhibit a trend of enrichment in W, V, and Sb and are always depleted in Nb. Analysis of rutiles demonstrates that their chemical composition can be used to distinguish between mineralized rocks and other types of non-mineralized rocks. The results indicate that the trace element composition of rutile, mainly the V content, and other elements such as Al, Zr, Sb, W, offer the best indications of mineralization in gold deposits.Item Acesso aberto (Open Access) Os efeitos dos manguezais e das intervenções humanas na dinâmica sedimentar das praias de SalinópoliS, PA(Universidade Federal do Pará, 2025-03-07) PÉREZ MARTINEZ, Julián David; COHEN, Marcelo Cancela Lisboa; http://lattes.cnpq.br/8809787145146228Salinópolis, on the coast of Pará, has become an important tourist hub, expanding its infrastructure along the coastal zone. This area is considered sensitive to sea-level rise. Therefore, identifying the area most vulnerable to coastal erosion is extremely important, especially due to the growth of coastal urban areas, which can interfere with sediment balance, intensifying erosion processes. This master's thesis aims to identify the effects of mangroves and coastal urban expansion on sediment balance along the beaches of Salinópolis. This study was carried out through a spatio-temporal analysis based on satellite (2003 – 2023) and drone data (2019-2024). The data revealed that the urban area expanded (627 ha), while the mangrove area fluctuated, increasing from 3630 ha to 3889 ha between 2003 and 2023. Erosion was identified along the beaches, particularly at Praia do Farol Velho (erosion = 432,625 m³, sedimentation = 217,259 m³). Praia do Atalaia (erosion = 115,415 m³, sedimentation = 462,630 m³) and the Maçarico/Corvina beaches (erosion = 640,389 m³, sedimentation = 801,670 m³) showed a trend of sediment accumulation. Erosion has predominantly occurred in the lower intertidal zone, while sedimentation has occurred in the supratidal zone and the upper intertidal zone. Residences, particularly in Farol Velho, may accentuate this process and Praia do Atalaia, which are currently located in the intertidal and supratidal zones in front of the mangroves. The walls built to protect these residences from waves and current action have also functioned as a barrier to retain sediments at the upper intertidal/supratidal transition. In much of Praia do Farol Velho, without these walls, there has been erosion in the intertidal zone, with a retreat of the coastline by about 100 meters between 2009 and 2023. However, the Maçarico/Corvina beaches have mangroves in front of the urban infrastructure, with sediment accumulation predominantly in the supratidal zone and the upper part of the intertidal zone. Human interventions on these beaches have not impacted the sedimentary dynamics until 2023. This beach provides a good example of how coastal infrastructure projects should be planned, using mangroves as protection against the action of waves and currents. However, the construction of beach access walkways in 2024 altered the hydrodynamic flow of a tidal channel, trapping tidal waters and creating muddy intertidal zones with porewater salinities close to 70 ‰. This process has already killed approximately 7 ha of mangrove. These data provide valuable insights to guide more efficient public and private investments, avoiding construction in high-risk areas or those that harm the mangroves, offering crucial information about coastal erosion and its impacts on urban infrastructure in the beaches of Salinópolis, especially in the face of sea-level rise.Item Acesso aberto (Open Access) Reconstituição paleoambiental da vegetação costeira na foz dos rios Santa Maria da Vitória e Jucu durante o holoceno médio e tardio, Estado do Espírito Santo, Brasil(Universidade Federal do Pará, 2025-03-13) PANTOJA, NISYA ROBELLY CARDOSO; FRANÇA, Marlon Carlos; http://lattes.cnpq.br/8225311897488790; https://orcid.org/0000-0002-3784-7702Climate and sea level changes may have caused significant alterations in coastal morphology and mangrove distribution on the central coast of Espírito Santo State, Brazil. Therefore, this study aims to identify the dynamics of coastal vegetation during the middle and late Holocene, in the Santa Maria da Vitória and Jucu rivers. For this purpose, 14C dates, sedimentary data and pollen data were used, obtained from two sedimentary cores, called RSMV (340 cm) and JUCU (190 cm). During the middle Holocene, around 7245-7368 cal years BP, the relative sea level (SSL) was above the current level, resulting in the development of mangroves in the RSMV core region. However, around 2699-2787 cal years BP, with the regression of the SSL, the mangrove area moved to topographically lower regions. Another determining factor for the reduction of these areas during this period to date was human intervention. In the JUCU core region, mangrove forests were identified between 2188-2332 cal yr BP, initially colonized by Laguncularia. Thus, in this context, the dynamics of vegetation and sediments are associated with fluctuations in relative sea level and climate change throughout the Holocene.Item Acesso aberto (Open Access) Análise da dinâmica da cobertura e uso do solo na bacia hidrográfica dos lagos Bolonha e Água Preta, Belém, Pará.(Universidade Federal do Pará, 2024-12-20) BARROS, Jackison Mateus Lopes; SOUZA FILHO, Pedro Walfir Martins e; http://lattes.cnpq.br/3282736820907252; https://orcid.org/0000-0003-0252-808XThe increase in the urban population in the world has impacted river basins that supply water to cities, including the treatment and distribution of drinking water for domestic, industrial and commercial use. One example is the Bolonha and Água Preta Lakes Hydrographic Basin (BHLBA) in the Belém Metropolitan Region (RMB), the second largest urban agglomeration in the Brazilian Amazon, with 2.3 million inhabitants. One of the best ways to monitor the dynamics of river basins is through remote sensing techniques with orbital images, due to the quality of the spatio-temporal data. This work aims to analyze the changes in land cover and use in the last four decades in the BHLBA, through images from the Landsat satellite series from the years 1984, 1989, 1994, 1999, 2004, 2008, 2018, 2021 and 2023, using a geographic object-oriented image analysis (GEOBIA) methodology. Thus, the classes of lakes (L), urban area (AU), aquatic macrophytes (MA), arboreal vegetation (VA) and pasture (P) were evaluated. The overall accuracy of the images showed values around 90%, with the main error being allocation errors. Changes that occurred over the years were identified, such as the significant growth of macrophytes on the water surface of the Bolonha and Água Preta lakes, which decreased by approximately 3.7%. A 13.4% increase in arboreal vegetation in the BHLHA was also recorded, evidencing a forest recomposition. A 3.2% growth in urban areas around the BHLBA was also observed, which is worrying because human influence can put the health of the water supply sources of the RMB at risk. The GEOBIA methodology proved to be adequate for the study and we recommend that monitoring be continued due to the socio environmental importance of the area under study.Item Acesso aberto (Open Access) Famílias hyriidae e mycetopodidae (Mollusca:Bivalvia) da Formação Solimões (Mio-Plioceno) bacia do Solimões, AM, Brasil: taxonomia, inferências paleobiogeográficas e paleoambientais.(Universidade Federal do Pará, 2024-06-16) ARAÚJO, Lorena Lisboa; RAMOS, Maria Inês Feijó; http://lattes.cnpq.br/4546620118003936; https://orcid.org/0000-0003-0276-0575The Solimões Formation, situated in western Amazonia, represents the Neogene sedimentary sequence from Solimões Basin. Its is correlated to Pebas Formation in Peru and is well known for its abundant and rich fossil content, including mollusks. Research on fossil mollusks bivalves from this unit began in the 19th century, with the Gabb (1868). These organisms have calcareous bivalve shell that allow their preservation, making them valuable tools in paleoecological, paleoenvironmental, biostratigraphy and paleogeography studies. Despite the abundance and diversity of this group in western Amazonia, in Brazil there is only few studies conducted. Therefore, the present study aimed the taxonomic identification of bivalve mollusks belonging to the families Hyriidae and Mycetopodidae and to contribute in paleoenvironmental and paleoecologic interpretations, as well as the paleobiogeographic distribution of the identified fauna. The study material comprised 200 samples collected from sedimentary banks along the Jurua and Javari rivers, near Eirunepé and Atalaia do Norte towns, Amazonas State, Brazil. The taxonomic analyses allowed the identification of three genera (Castalia, Diplodon, and Prisodon) from the family Hyriidae, and one genus (Haasica) from the family Mycetopodidae. The fossil assemblage consists exclusively of freshwater taxa, indicating lacustrine and fluvial environments during the upper Miocene in the study area. The genus Castalia exhibits a wide geographical distribution, primarily in South America, with its oldest records dating to the Cretaceous. Its absence in the Paleogene may be attributed to limited studies of this period in Brazil, which focused mainly on marine basins. Meanwhile, records of the genus Diplodon span from the Jurassic to the upper Miocene. For the first time, fossil evidence of both genus Prisodon and Haasica was identified in the Miocene.Item Acesso aberto (Open Access) A resiliênca dos manguezais do estuário do rio Ceará Mirim-RN às intervenções humanas.(Universidade Federal do Pará, 2024-09-23) AQUINO, Ronaldo Darlan Gaspar; COHEN, Marcelo Cancela Lisboa; http://lattes.cnpq.br/8809787145146228Mangroves are recognized for being extremely sensitive to changes in the physical and chemical environment and are widely used as indicators of changes in climate, sea level, and human interference. The study area comprises the mouth of the Ceará-Mirim/RN River, located on the coast of the state of Rio Grande do Norte (RN), in northeastern Brazil. This area has a history of mangrove deforestation for implementing shrimp farming. This study aims to analyze the mangrove dynamics from 1985 to 2020. The research uses orbital remote sensing and drone images to develop a spatial-temporal analysis. The data indicates that despite the expansion of aquaculture activity from 46 ha to 183.47 ha considering active and inactive tanks, there was an increase in mangrove areas from 351 to 489 ha. Over the 35 years, aquaculture activity has mainly occupied flooded fields and apicum regions and occasionally some areas have been converted from mangrove areas. However, the expansion in mangrove areas was mostly due to the abandonment of aquaculture, which before 1985 suppressed mangroves to construct ponds. Despite severe anthropogenic interference in this delicate ecosystem, these forests have shown great resilience by recolonizing their tidal flats.Item Acesso aberto (Open Access) Evolução da paisagem da porção centro-oriental da Amazônia do Cretáceo ao Paleógeno.(Universidade Federal do Pará, 2024-06-23) MOURA, Matheus Ramos de; NOGUEIRA, Afonso César Rodrigues; http://lattes.cnpq.br/8867836268820998This study presents a new perspective for the evolution of the relief in Central and Eastern Amazonia based in geomorphologic and stratigraphic analysis of two areas: the first one at the surroundings of Paragominas and the second includes territories from Juruti, Belterra and Santarém counties, both at the state of Pará. The results of the relief analysis demonstrate a diversity of morphological modellings that indicate a polycyclic evolution involving periods of development of flat plateaus, associated with the development of lateritic profiles, alternated with intervals that tend to erosional activity from unstable and collapsing slopes, being the planation reliefs representative of the Paleocene-Eocene and Early-Middle Miocene, while the dissection modellings mark ages from the Neoeocene-Neooligocene and Neomiocene-Pliocene. The ages of the planation modellings are confirmed by age estimations of Cenozoic paleosurfaces that occur along the Amazon region (with which they are correlatable) and by global eustatic and climatic tendencies. The sedimentological and stratigraphic analysis identified two typical profiles for these study areas – PWH (profiles with well-defined horizons) and PMC (profiles with massive conglomerates), distinguished by their in situ/reworking characteristics. Regarding to the PMC profiles, there were observed two facies associations: FA1: an association of conglomerates of diverse supportings and arenites assumed to be formed by proximal fan deposits generated through debris flows; and FA2: packs of clay displaying mostly a massive framework, interpreted as distal fan deposits generated through sheet flow and mudflow. Both associations have subaerial exposure evidence and erosive surfaces in their bases, that allow to conclude a deposition at embedded valleys through rapid pulses of detritus, and hence were interpreted as colluvial and alluvial fan deposits, that formed along the most erosive periods of the regions, having been initiated in the vicinities of the main drainages of the analyzed areas (Capim and Amazonas rivers). The results of this study demonstrate a more intense sedimentary and tectonic activity than that generally accepted for the Amazon region during the Cenozoic Era, showing that this region’s landscape was more affected than it was believed to be by another tectonic remarkable events in the South America continent, such as: the Andes Uplift, the deposition of the Amazonas and Marajó basins and Bragantina Platform neogene formations, the Tortonian Regression and the install and evolution of the Amazonas River.Item Acesso aberto (Open Access) Petrologia magnética e parâmetros de cristalização do Charnoquito Rio Seco: Implicações para evolução de granitos neoarqueanos da Província Carajás.(Universidade Federal do Pará, 2024-10-09) SANCHES NETO, Silvio; OLIVEIRA, Davis Carvalho de; http://lattes.cnpq.br/0294264745783506; http://lattes.cnpq.br/0294264745783506 Orcid iD ? https://orcid.org/0000-0001-7976-0472This work presents new magnetic petrological data and crystallization conditions (T, fO2 and xH2O) of the Rio Seco Charnockite from a detailed study of the textural evolution of silicates and Fe-Ti oxide. The body is intrusive in Mesoarchean granitoids (2.88 Ga) and was subdivided into four petrographic types: (i) gabbronorite; (ii) ortho-clinopyroxene granodiorite; (iii) clinopyroxene-hornblende monzogranite; (iv) hornblende-biotite monzogranite. The magnetic values range from 0.231x10-3 to 22.1x10-3 Slv and shows bimodal character. Pyroxene-bearing rocks are concentrated in magnetic population A, whose magnetic susceptibility values range from 3.2x10-3 to 22.1x10-3, and are compatible with the SM values defined for oxidized neoarchean granites of the Carajás Province. Pyroxene-deprived rocks define magnetic population B, with lower values, between 0.231x10-3 and 0.309x10-3. They are included in the range of values defined for reduced granites. The amphibole crystallization temperature ranges from 713 to 809°C and the emplacement pressure ranges from 81 to 300 MPa. The fO2 (ΔNNO) ranges from -0.4 to +2.4 and the log fO2 from -12.0 to -16.0. The low Fe/(Fe+Mg) ratio in hornblende and biotite confirms the oxidizing conditions of these rocks, which belong to the magnetite series. The hygrometer used indicated water content in the magma ranging from 4.3 to 6.1% wt. The corona-type textures record the physical-chemical disequilibrium between silicates and favor the formation of magnetic minerals in the rocks with pyroxene. The rocks of population A present modal content of opaque minerals ranging from 0.2 to 1.7% with different degrees of exsolution of ilmenite in the magmatic stage (magnetite-ulvospinel series). The magnetic population B shows lower contents of opaque minerals (<0.3%) and is characterized by the presence of zoned goethite formed by oxyhydration processes in the late to post magmatic stage. The study of textural and mineralogical evolution reinforces the fractional crystallization model proposed in a previous work and explains the abundance of Fe-Ti oxide minerals in the variety with orthopyroxene, giving these rocks an oxidized character. The Charnockite Rio Seco has its emplacement controlled by a system of lineaments with ductile ruptile behavior, which is favorable to the interpretation of a pluton emplaced at shallow crustal levels. In deeper crustal conditions, the assimilation of crustal components may give rise to ferrous magmatism.Item Acesso aberto (Open Access) Monitoramento hidrológico e sensoriamento remoto em estuários amazônicos: análise da variação espacial e temporal de sedimentos.(Universidade Federal do Pará, 2024-10-13) AVIZ, Matehus Dias de; POLIDORI, Laurent; http://lattes.cnpq.br/7680664269303426; https://orcid.org/0000-0001-6220-9561Monitoring aquatic environments generally requires high technical, scientific and financial investment. The existence of dedicated monitoring networks is necessary to guarantee spatial and temporal continuity. However, data quality also depends on standardization, from sample collection to parameter analysis. Studies show that the biggest challenge in Brazil is the scarcity of financial resources, resulting in data discontinuity. Inter-institutional cooperation is essential to overcome these obstacles and promote long-term monitoring. In this context, remote sensing has emerged as a fundamental auxiliary tool, complementing traditional monitoring by providing data on various aquatic variables, such as height, temperature and concentration of optically active components, especially in conditions of restricted financial resources or governance problems. Spatio-temporal variations in water color in an estuary are affected by various physical and hydrological components, which makes understanding them complex. In this study, we sought to understand the spatio-temporal variation of water color, for sampling purposes, in an estuary on the Amazon Coast. The study area for this study is located in the estuary formed by the confluence of the Pará (Tocantins, 5% of the Amazon River), Guamá and Acará rivers, near the island of Tatuoca, 10 km from Belém. The region is influenced by the Marajó and Santo Antônio bays, which have different bottom morphologies, affecting local currents. The climate has two seasons: rainy (December to May) and less rainy (June to November). The tides are meso and macro semidiurnal, with amplitudes of up to 3.7m. To achieve our objectives, we applied geostatistical and statistical tools to test the spatio-temporal variability of water color, based on multisensor reflectance data, Landsat-8/9 and Sentinel-2 in the red band. The spatial variation showed distances of more than 48 m ±4.26 at high tide and 44 m ±7.62 at low tide. For the temporal variation, we found that the monthly variations are significant according to seasonality and show the same variation in the different phases of the tide (high, low and equinoctial). Therefore, the color of the water in the Tatuoca Island region shows geostatistical and statistically significant spatio-temporal variation. The distances and temporal frequency of sampling should be adjusted according to the tides and seasonality to ensure that the data is sampled according to the variations in the environment.Item Acesso aberto (Open Access) Otimização da síntese de pigmentos zeolíticos ultramarinos derivados de rejeito de caulim usando um DOE 2ˆ3 completo.(Universidade Federal do Pará, 2024-07-03) JESUS, Geyna Evellyn Silva de; PAZ, Simone Patrícia Aranha da; http://lattes.cnpq.br/5376678084716817; https://orcid.org/0000-0002-5880-7638The state of Pará is recognized as an important center for kaolin production for paper coating, resulting in a significant amount of waste, mainly composed of kaolinite. Research groups at the Federal University of Pará have been exploring the use of this waste as an alternative source of silicon and aluminum in the synthesis of zeolites, particularly zeolite A, which has the potential for producing ultramarine pigments. These inorganic pigments are highly valued due to their deep blue color and good chemical and physical stability. LTA and sodalite zeolites are the main crystalline structures involved in this process, with the S3⁻ anionic radicals responsible for the blue color. The synthesis process involves calcination of the zeolite with sulfur and sodium carbonate, resulting in the diffusion of sodium polysulfides through the zeolite pores and the production of pigments with color variations depending on the synthesis conditions. The aim of the study was to understand how the crystalline structure of zeolites (LTA zeolite and sodalite) affects the pigment color and to propose an optimization for the more efficient synthesis of these pigments. To achieve these objectives, a sequential experimental design methodology (DOE) was applied. A Full Factorial Design followed by a Central Composite Design was used to identify the significant and influential factors in obtaining the ultramarine blue color. For optimization, the response surface methodology was employed in conjunction with the Excel Solver function. The response obtained was color, and the factors were temperature, time, and S/Na2CO4 ratio. The analyses that supported the crystallochemical discussion were: Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray fluorescence (XRF), differential scanning calorimetry (DSC), and thermogravimetry (TG), particle size distribution (PSD), zero point charge (ZPC), and UV-Vis diffuse reflectance spectroscopy, and Munsell Color System was used for color classification. The crystallochemical analyses of the pigments obtained from LTA zeolite revealed the insertion of S3⁻ chromophores into the zeolitic structure, which was corroborated by FTIR and DSC-TG analyses, highlighting characteristic peaks of these phases. UV-Vis spectroscopy revealed the presence of both S2⁻ (associated with green hue) and S3⁻ (associated with blue hue) chromophores, with the optimized product showing a higher concentration of S3⁻ chromophore, indicating the effectiveness of the planning. On the other hand, UV-Vis analysis of the pigment derived from sodalite did not show characteristic peaks of the chromophores of interest. Finally, this research assumes significant relevance in the global context of environmental impacts resulting from waste generation, offering a promising alternative for the management of kaolin waste and the production of synthetic ultramarine pigment. The synthesis of this pigment from LTA zeolite represents a more environmentally sustainable approach due to the almost negligible reduction in sulfur oxide emissions, positioning itself as a viable and environmentally conscious solution for obtaining this type of pigment.Item Acesso aberto (Open Access) Afinidades petrológicas e geocronologia U-Pb em zircão de ortognaisses do Complexo Gnáissico-Migmatítico Água Azul, Terreno Sapucaia, Província Carajás.(Universidade Federal do Pará, 2024-10-09) PINTO, Eliziane de Souza; OLIVEIRA, Davis Carvalho de; http://lattes.cnpq.br/0294264745783506; https://orcid.org/0000-0001-7976-0472The Água Azul do Norte area is part of the geological context of the Carajás Province, precisely in the Sapucaia Terrain, according to the recent tectonic compartmentalization proposals presented by the Granitoid Petrology Research Group (GPPG/UFPA). This region is formed by a mesoarchean orthognathic basement with TTG affinity (Água Azul GneissicMigmatitic Complex; 2.93 Ga) associated with late Mesoarchean intrusions with sanukitoid signatures (Água Azul and Água Limpa Granodiorites; 2.88-2.87 Ga), high-Ba-Sr sodic (Nova Canadá Granodiorite; 2.89-2.87 Ga) and high-K calc-alkaline (Boa Sorte Granite; 2.89- 2.85 Ga) signatures. The review of geological and petrographic data indicated that the TTG crust of Água Azul do Norte is compositionally heterogeneous and records strong evidence of progressive metamorphism and migmatization. Therefore, this work reclassifies this TTG basement as being formed by orthogneisses, which occasionally present variations to tonalitic to quartz dioritic compositions that resemble fragments of a more primitive, intensely deformed and gneissified crust. These varieties show compositional banding in an E-W direction, often disturbed by shear bands and drag folds. Considering the classification of migmatites, they have an orthognathic paleosome and leucosomes rich in Qz+Pl±Bt parallel to the banding (stromatic metatexite) and frequentely outlined by mafic aggregates (melanosome rich in biotite and hornblende). They form four compositional varieties: i) hornblende±biotite tonalitic orthogneiss (HBTnl), ii) clinopyroxene-hornblende tonalitic orthogneiss (CHTnl), iii) epidote-biotite orthogneiss quartz diorite (EBQzD) and iv) hornblende-biotite orthogneiss quartz diorite (HBQzD). They present a large proportion of mafic minerals (M'> 15%), especially biotite and hornblende, which can occur slightly stretched along the foliation plane. Plagioclase and secondary quartz are abundant and occur in the matrix or, in the case of plagioclase, as phenocrysts, while alkali-feldspar and primary quartz are practically insignificant. Whole rock geochemical analysis indicated that samples MED-120A (EBQzD) and MEP-53B (HBQzD) present moderately magnesian character, medium-K calcium-alkaline signature, relative depletion in K2O, MgO, Ba, Ni and Cr and enrichment in Na2O, Al2O3, TiO2, Fe2O3 and Zr, reflecting a certain affinity with traditional tonalite-trondhjemitic associations. The presence of many zircon crystals with igneous features preserved in these samples marks the crystallization age of the protolith at 3.06 Ga, suggesting that they are crustal fragments approximately 100 Ma older than the underlying crust (Água Azul Orthognathic Complex). MED-144 (HBTnl) exhibited a strongly magnesian character, high-K calcium-alkaline signature, high K2O/Na2O ratio and enrichment in MgO, Ba, Ni and Cr, very similar to the composition observed in sanukitoids. The U-Pb data obtained for this sample indicated a crystallization age of 2.92 Ga, similar to that observed in sanukitoids described in the Ourilândia do Norte region (Arraias Granodiorite). The other samples showed significant contents of compatible elements (e.g. Fe, Mg, Ni, Cr) and moderate contents of incompatible elements (e.g. K, Rb, Ba, Sr, Zr, Ti) and revealed an intermediate behavior between TTGs and granitoids enriched in Mg, as well as a strong affinity with the São Carlos Orthogneiss (2.93 Ga) described in the same terrain. Concordant U-Pb ages obtained for samples MED-95A (HBTnl) and EDC-28B (CHTnl) indicated acrystallization at 2.95-2.93 Ga contemporaneous with the emplacement of the Água Azul TTGs and the São Carlos Orthogneiss. The textural behavior of the quartz and mafic minerals indicates dynamic recrystallization mechanisms at intermediate to high temperatures (~500-650ºC), while the morphology observed in the migmatites (stromatic metatexitic and leucosomes with hydrated minerals) suggests that there was a low amount of melt produced and fluids participation in the partial melting process. Combined with the mineral paragenesis (Pl+Qz+Bt±Hbl±Ep), these factors point to a granitic protolith metamorphosed under amphibolite facies conditions, with the migmatization being strongly contemporaneous with the deformation and peak of the regional metamorphism described in the Carajás region (2.89 Ga; MED-95A).Item Acesso aberto (Open Access) Síntese e caracterização da piroaurita e hidroalcita a partir do horizonte laterítico da mina de bauxita de Juruti (PA).(Universidade Federal do Pará, 2024-10-01) ARAÚJO, Bruno Eduardo Oliveira de; CORRÊA, José Augusto Martins; http://lattes.cnpq.br/6527800269860568Anionic clays, also known as LDH, are nanomaterials with diverse technological applications, as well as versatile nanocomposites with properties such as ion exchangers, adsorbents, catalysers, and the ability to simulate cations and anions in their lamellar structure, which expands their applications as environmental remediators. Mining activities in the Amazon are growing exponentially, so it is necessary to find sustainable and practical ways to minimize environmental charges. Another possibility is the reuse of mining waste with specific applications in the recovery of chemical elements through concentration processes in tailings piles or treatment of acid mining drainage. Bauxite deposits have been explored for 15 years in the Juruti city, Pará state, and are part of the world's largest reserves, with high levels of aluminium oxide (Al2O3). The exploration and processing of aluminium mining leave large lakes where the disposal of tailings occurs. There are several studies that aim to use bauxite dispersion as a starting material for the synthesis of LDH, however this work focuses on the synthesis of LDH from the lateritic horizon, which makes up one of the six horizons of the lateritic-bauxitic profile of Juruti mines. The high levels of Fe3+ and Al3+ observed in the lateritic horizon allow its use as a starting material, together with magnesium chloride and sodium hydroxide to create optimized conditions for the synthesis of LDH by the coprecipitation method at variable pH. X-ray diffraction (XRD), scanning electron microscopy (SEM), spectrometry (FTIR), thermal analysis (TG-DSC) and surface area analysis (BET) techniques were used to characterize the synthesized LDH. The crystalline phases include pyroaurite (Mg2Fe(OH)16CO3.4H2O) and hydrotalcite (Mg6Al2(OH)16CO3.4H2O), in addition to brucite, spinel (mixed oxide) and hematite as secondary phases. Scanning electron microscopy (SEM) showed characteristic LDH morphologies, with small crystals with hexagonal habits, rougher structures and plate-like shapes that resemble honeycombs, when grouped, Infrared spectra (FTIR) indicated the presence of carbonate ions in the interlayer space in both types of LDH, through the characteristic weak absorption bands around 1373.51 –1394.67 cm-1. The conjugate TG/DSC curves indicated three endothermic events for the pyroaurite-type LDH, in addition to an exothermic event at a higher temperature, forming spinel, while the hydrotalcite-type LDH presented four endothermic events. The total mass loss of hydrotalcites is 15%, while that of pyroaurites reaches approximately 50%. Regarding the surface and porosity analysis (BET), a specific surface area (ASEBET) of 74.397 m2/g and a pore volume (VPBJH) of 0.173 cm3g-1 were obtained, and the average pore diameter was 18.64 Å. The ASEBET values of the hydrotalcite-type LDH are considerably higher, with similar VPBJH and pore radius values. The physisorption isotherm is type IV with hysteresis curve H3 that is associated with mesoporous structures as some clays and particle aggregates, such as plates with narrow slit-type pores. Thus, from the defined synthetic routes and having the lateritic horizon as a low-cost starting material, it is possible to continue adsorption tests using pyroaurite and hydrotalcite, synthesized and characterized in this work, with efficient potential to mitigate metal contamination in water resources.Item Acesso aberto (Open Access) Foraminíferos bentônicos da Formação Pirabas (Oligoceno-Mioceno), Plataforma Bragantina, nordeste do Estado do Pará, Brasil.(Universidade Federal do Pará, 2024-06-19) BENAVIDES PÉREZ, Mónica Andrea; NOGUEIRA, Anna Andressa Evangelista; http://lattes.cnpq.br/2549136312354338; https://orcid.org/0000-0002-6330-4760The Bragantina platform occurs off the northern coast of Brazil and is delimited by the Bragança - Vizeu Basin to the east and the Guamá Arch to the south. The Pirabas Formation units of this platform as it has a rich fossiliferous content including vertebrates and invertebrates (especially foraminifera and ostracoda). This unit consists of carbonate and siliciclastic sediments deposited during transgressive and regressive episodes (Chattian-Burdigalian), intensely modifying the coastline in northern Brazil. In this study, benthic foraminifera were analyzed in 27 samples from core FPR-192, in the town of Primavera, northeast of the state of Pará, Brazil. Paleoenvironmental, paleoecological and paleobiogeographic conditions were inferred using multivariate and ratio (P/B) analyses, designating six biofacies, three associations, variations in paleoprofundity and six paleoecological variations from coastal or transitional zones (hypersaline to brackish lagoons, estuaries) to carbonate platforms (internal, middle and external). Local biozonation was proposed for the studied section based on benthic foraminiferal bioevents. These associations reflected three main ecozones according to paleoecological events related to sea level variations. These ecozones were defined and named five Partial Amplitude Zones (PAZ): Amphistegina lessonii, Heterolepa dutemplei, Elphidium crispum, Siphonina pulchra and Bolivina subcompressa; and one Concurrent Amplitude Zone: Buccella peruviana. The biochronostratigraphy of the section studied was based on the local appearance of A. lessonii and H. dutemplei (lower Oligocene, Rupelian) and the stratigraphic distribution of E. crispum, S. pulchra and B. subcompressa.