PPGG - Mestrado em Geodinâmica e Geofísica
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Master Thesis Batimetria derivada de satélite: um método de baixo custo para análise da plataforma rasa no litoral cearense - margem equatorial brasileira(Universidade Federal do Rio Grande do Norte, 2025-12-10) Pereira, Igor Silva; Gomes, Moab Praxedes; https://orcid.org/0000-0003-0836-1073; http://lattes.cnpq.br/2086362176219605; Ximenes Neto, Antonio Rodrigues; http://lattes.cnpq.br/3140578236224142; Almeida, Narelle Maia de; https://orcid.org/0000-0003-2586-4502; http://lattes.cnpq.br/4905966563292686; Araújo, Paulo Victor do Nascimento; https://orcid.org/0000-0002-0625-0946; http://lattes.cnpq.br/4073388836947213Bathymetry is an important tool for research and mapping of the submarine relief; however, its operation has high costs and logistical limitations. As an alternative, SatelliteDerived Bathymetry presents itself as a low-cost, sustainable, and easily applicable method, although it presents challenges in regions with turbidity and/or suspended sediments in the water column, such as the Ceará shelf in the Brazilian Equatorial Margin. Thus, this study aims to develop and validate a low-cost and accessible methodological script for the application of the empirical Satellite-Derived Bathymetry method along the Ceará coast. Satellite images were used within the Google Earth Engine platform and were modeled and statistically analyzed (R², RMSE, and MAE) within R Studio, and a final analysis was carried out based on observed and modeled bathymetric profiles. The results, through statistical analyses and bathymetric profiles, indicated the M4 model – single-image as the best model, while the M5 model (multi-image and single-image) was the second best, with R² above 0.6. Thus, it is concluded that the proposed method is a viable and sustainable tool to map shallow zones, up to 20 m, even in zones with turbidity or suspended sediments, with the appropriate considerations of the area, and it is necessary to choose models for each region for a better overall result.Master Thesis Batimetria derivada de satélite aplicada a região da plataforma continental adjacente a Caiçara do Norte, Rio Grande do Norte, Brasil(Universidade Federal do Rio Grande do Norte, 2025-12-03) Rocha, Débora Joyce do Nascimento; Gomes, Moab Praxedes; https://orcid.org/0000-0003-0836-1073; http://lattes.cnpq.br/2086362176219605; http://lattes.cnpq.br/8034653867571607; Nogueira, Mary Lucia da Silva; https://orcid.org/0000-0001-5163-9793; http://lattes.cnpq.br/2546229173660779; Araújo, Paulo Victor do Nascimento; https://orcid.org/0000-0002-0625-0946; http://lattes.cnpq.br/4073388836947213; Araújo, Tereza Cristina Medeiros de; https://orcid.org/0000-0003-2760-6566; http://lattes.cnpq.br/4130469620831742The continental shelf in northern Rio Grande do Norte is subdivided into inner, middle, and outer shelf sectors and is extremely shallow, with depths reaching up to 70–75 m over most of its extent. Despite the presence of several submarine features, detailed bathymetric studies in this region are scarce, which limits the understanding of its morphology and hampers the acquisition of high-resolution bathymetric surveys. This study proposes the application of satellite-derived bathymetry (SDB) using empirical models applied to multispectral optical imagery as a support tool for mapping shallow-water environments. The objective of this study is to apply SDB to investigate depth and seafloor morphology and to morphologically characterize the Coroa das Lavadeiras, a shallow, isolated sandy body located north of the continental shelf of Rio Grande do Norte, near the municipality of Caiçara do Norte. The proposed methodology is based on multispectral images from the Landsat-8 OLI and Sentinel2A sensors, combined with depth data extracted from nautical charts. After atmospheric correction, empirical methods based on band ratios and polynomial model fitting were applied to estimate water depth. Model performance was evaluated using statistical metrics, including the coefficient of determination (R²), root mean square error (RMSE), mean absolute error (MAE), and mean absolute relative deviation (MARD). The results indicate that the model developed using Landsat-8 data, within the 2–30 m depth range and employing the blue and green band combination (B1/B2), achieved the best performance, with an R² of 0.71 and the lowest error values. The final application of this model enabled the generation of a representative bathymetric map, bathymetric profiles, and three-dimensional models, allowing the identification of submerged morphological features such as the Coroa das Lavadeiras, longitudinal dunes, and transverse dunes, highlighting the potential of the SDB approach for mapping shallow areas of the inner continental shelf of Caiçara do Norte.Master Thesis Paleoicnologia de Crocodylomorpha e sua ocorrência na Bacia Rio do Peixe (Cretáceo Inferior), Nordeste do Brasil(Universidade Federal do Rio Grande do Norte, 2025-11-18) Erickson, Rebecca Fernandes; Ghilardi, Aline Marcele; Aureliano Neto, Tito; https://orcid.org/0000-0002-3636-6691; http://lattes.cnpq.br/4939990304937816; Araújo Júnior, Herminio Ismael de; Marinho, Thiago da SilvaThe Tapera ichnosite, located in the Rio do Peixe Basin (Paraíba, Brazil), preserves a unique suite of vertebrate trace fossils within fluvio-palustrine deposits of the Barremian–Hauterivian Sousa Formation. This sedimentary unit, developed under semi-arid climatic conditions with episodic waterlogging and cohesive substrates, provides ideal conditions for exceptional soft-sediment preservation. Through high-resolution 3D modeling and sedimentological analysis, we re-evaluate crocodylomorph traces previously documented at the site, expanding the ichnological dataset and refining behavioral interpretations. The trackways include deep ventral impressions and rhythmic lateral sediment disruption, occasionally accompanied by pes and manus prints, and are interpreted as records of large-bodied crocodyliforms using low-walking and belly-sliding locomotion across a gently inclined, water-saturated substrate. The ichnological features closely align with the ichnogenus Crocodylopodus, though the Tapera traces notably exceed its known size range and present unusually prominent ventral morphology. These findings contribute to the understanding of vertebrate-substrate interaction in continental rift basin environments and provide new data for the paleoenvironmental and paleobiogeographic reconstruction of the Early Cretaceous in central Gondwana.Master Thesis Integração de métodos petrofísicos para caracterização multiescala de sistemas porosos em rochas carbonáticas da Bacia Potiguar(Universidade Federal do Rio Grande do Norte, 2025-09-19) Carvalho Filho, Irosvaldo Ferreira de; Xavier Júnior, Milton Morais; http://lattes.cnpq.br/3128669965557866; http://lattes.cnpq.br/0214549347192524; Souza, André Alves de; Xavier Neto, Pedro; http://lattes.cnpq.br/0420885770350995This dissertation presents a comparative analysis of petrophysical techniques applied to the characterization of porous systems in carbonate rocks, focusing on a set of 101 samples from the Potiguar Basin, of which 9 were exclusively allocated for digital analyses. The study integrated traditional methodologies, such as gas porosimetry and water saturation porosity, with advanced digital imaging techniques, including X-ray microtomography (Micro-CT), synchrotron radiation tomography (SR-CT), and Nuclear Magnetic Resonance (NMR) measurements. The research highlighted the complementary nature of these methods, demonstrating how each technique accesses specific fractions of the porous system: gas porosimetry proved highly efficient in determining interconnected volumes; water saturation revealed the fraction effectively occupied by mobile fluids; NMR stood out for its sensitivity to micropores; while microtomography enabled detailed characterization of structural connectivity and three-dimensional morphometry of the porous medium. The results indicate that variations between techniques are explained by factors such as the presence of unsaturated pores, trapped air, wettability limitations, and differences in image resolution. From a statistical standpoint, the integration of scatter plot analyses with ANOVA and Tukey HSD tests confirmed significant differences between lithofacies and among the applied methods, reinforcing the importance of multitechnique approaches in the petrophysical characterization of carbonate reservoirs.Master Thesis Caracterização química e mineralógica de fosfatos de alumínio da falha de Samambaia, Rio Grande do Norte(Universidade Federal do Rio Grande do Norte, 2025-08-13) Aguiar, Adriano Henrique Andrade de; Vilalva, Frederico Castro Jobim; Menezes, Cristiane Paulino de; https://orcid.org/0000-0003-3399-6863; http://lattes.cnpq.br/6227637633613443; http://lattes.cnpq.br/2681154572035243; Andrade, Fábio Ramos Dias de; http://lattes.cnpq.br/6287624855922912; Souza, Raquel Franco de; https://orcid.org/0000-0001-8818-0605; http://lattes.cnpq.br/5181465668193577The Samambaia Fault in Rio Grande do Norte represents a seismogenic structure of relevance in the tectonic context of Brazil, characterized by intense neotectonic activity and hydrothermal alterations in fracture zones. In this scenario, aluminum phosphate mineralizations with potential role in sealing and diagenetic evolution of these zones were identified. This research aims to characterize texturally and chemically the phosphate phases present in veins and breccias of the Samambaia Fault, understand their formation mechanisms, and discuss their implications in the hydrothermal and supergene alteration history of the region. Integrated analyses of XRD, QEMSCAN, SEM/EDS, and EPMA were employed on samples collected from different fault zones. The data allowed identification of mineralogy, chemical composition, and textural relationships between phosphate phases and associated minerals. The main aluminophosphates identified were variscite, crandallite, and millisite/wardite, associated with kaolinite and quartz. Variscite is the predominant mineral, with wide compositional variation (Al³⁺⇌Fe³⁺ substitutions). Crandallite and millisite/wardite occur subordinately, suggesting evolution under different fluid pulses. Textural evidence indicates that phosphates precipitated in acidic and low-temperature environments, with predominance of meteoric fluids. The presence of aluminophosphates in the Samambaia Fault results from multiple chemical alteration events, with strong pH control and phosphorus activity. These minerals may play a relevant role in permeability reduction in fractured zones. Future studies should integrate isotopic, petrophysical, and experimental data to elucidate fluid origin, mineral stability, and impacts on fault dynamics.Master Thesis Influência da Zona de Fratura Romanche na evolução tectono-sedimentar do setor central da Margem Equatorial Brasileira(Universidade Federal do Rio Grande do Norte, 2025-09-02) Carvalho, Saywry Virginio de; Castro, David Lopes de; https://orcid.org/0000-0003-1110-9389; http://lattes.cnpq.br/8279954644750743; http://lattes.cnpq.br/3648255462565207; Melo, Alanny Christiny Costa de; http://lattes.cnpq.br/6542699550245691; Xavier Neto, Pedro; http://lattes.cnpq.br/0420885770350995The Brazilian Equatorial Margin has emerged as an area of significant scientific and economic interest due to its high petroleum potential, evidenced by major discoveries along conjugate margins of the Equatorial Atlantic. This study investigates the influence of the Romanche Fracture Zone on the tectono-sedimentary evolution of the Barreirinhas Basin, located in the central sector of the Brazilian Equatorial Margin and Guina. Based on integrated analysis of five seismic sections and three exploratory well, structures typical of transtensional environments were identified, including normal faults, listric faults, and negative flower structures, affecting both the basement and overlying sedimentary sequences. These features demonstrate strong tectonic control by the Romanche Fracture Zone over the morphology of the continental shelf, slope, and the internal compartmentalization of the rift and drift sequences. The evolution of the Barreirinhas Basin reflects a complex interaction between oblique rifting, strike-slip regimes, and later tectonic reactivations, classifying it as a pull-apart basin. The current configuration of the margin, marked by distinct structural segmentations, underscores the fundamental role of fracture zones in the genesis and development of basins along the Brazilian Equatorial Margin. The results presented contribute to a better understanding of the structural controls on petroleum systems in the equatorial margin and highlight the importance of future studies involving structural modeling and threedimensional geophysical characterization.Master Thesis Controle estratigráfico sobre a silicificação hidrotermal na falha Afonso Bezerra, Bacia Potiguar, Brasil(Universidade Federal do Rio Grande do Norte, 2025-07-28) Sousa Neto, João Felipe de; Gomes, Moab Praxedes; https://orcid.org/0000-0003-0836-1073; http://lattes.cnpq.br/2086362176219605; http://lattes.cnpq.br/8862412125823088; Vasconcelos, David Lino; http://lattes.cnpq.br/1404826919358723; Barbosa, José Antonio; https://orcid.org/0000-0001-8754-6310; http://lattes.cnpq.br/9551646929257730; Xavier Neto, Pedro; http://lattes.cnpq.br/0420885770350995Hydrothermal silicification has a significant impact on petrophysical properties of reservoir rocks. The main constraints on silica-rich fluids are the faults, their damage zones, and variations in the host lithology. However, although the influence of host lithology on silicification is partially understood, further studies are required to clarify its role and spatial impact. In this study, the Cretaceous sequences of the Potiguar Basin, comprising the sandstones of the Açu Formation and the limestones of the Jandaíra Formation, as well as the crystalline rocks of the Neoproterozoic basement, are crosscut by the Afonso Bezerra Fault System, where significant occurrences of hydrothermal silicification are observed from the basement to the surface. This study employed seismic data, along with well data, and applied seismic attributes to enhance the visualization and mapping of stratigraphic units and the geometry of the hydrothermal silicification. A statistical spatial analysis of the silicified body was conducted to assess the relationship between silicification and stratigraphy. The results revealed that silicified body concentrate along the strike of the Afonso Bezerra Fault, which appears to be the main conduit controlling the uprise of hydrothermal fluids. Width variations and shape changes of the silicified zone connected to the variations of lithology. Carbonate rocks exhibit extensive silicification associated with wider volumes of affected rocks, whereas siliciclastic rocks show narrower and less pervasive silicification. In the crystalline basement, silicification is confined to fault zones. This spatial distribution evidences the primary control of tectonics and host lithology on hydrothermal fluid flow, thereby enhancing our understanding of hydrothermal silicification compartmentalization.Master Thesis Utilização de técnicas de decomposição espectral, condicionamento e atributos sísmicos para realçar falhas em um dado sísmico 3D localizados na região de Estreito/Alto do Rodrigues(Universidade Federal do Rio Grande do Norte, 2025-04-28) Silva Júnior, José Romero dos Santos; Antunes, Alex Francisco; https://orcid.org/0000-0002-3292-4190; http://lattes.cnpq.br/1519973126832391; http://lattes.cnpq.br/4404081246897982; Silva, Carlos César Nascimento da; http://lattes.cnpq.br/5136096872133075; Oliveira, Karen Maria Leopoldino; https://orcid.org/0000-0001-9061-7183; http://lattes.cnpq.br/8255754911585494The application of spectral decomposition and structurally oriented filtering techniques proved effective in enhancing the structural interpretation of seismic data. This study aimed to optimize the seismic bandwidth and improve the signal-to-noise ratio in a 3D seismic volume from the Estreito/Alto do Rodrigues field, located in the central-southern portion of the Potiguar Rift. The adopted methodology involved segmenting the seismic data into overlapping frequency sub-bands (15–85 Hz), applying the Dip Steering Median Filter (DSMF), and using seismic attributes such as similarity, pseudo-relief, Fault Likelihood (FL), and Thinned Fault Likelihood (TFL) to improve fault identification. As expected due to seismic attenuation, lower-frequency bands allow for the visualization of deeper structures in the sections, while higher-frequency bands exhibit more segmented reflectors, which can hinder seismic interpretation. The combined use of spectral filtering and attribute analysis enabled a more detailed interpretation of fault-related structures, including a flower structure, a possible inversion structure, and major faults trending northeast-southwest.Master Thesis Petrologia e gravimetria do segmento Norte do Batólito Acari, faixa Seridó: condições de alojamento e estruturação profunda(Universidade Federal do Rio Grande do Norte, 2025-05-15) Rocha, Christian Campos Batista; Motta, Rafael Gonçalves da; Vilalva, Frederico Castro Jobim; https://orcid.org/0000-0003-3399-6863; http://lattes.cnpq.br/6227637633613443; https://orcid.org/0000-0002-4334-4140; http://lattes.cnpq.br/9582385541342256; http://lattes.cnpq.br/0822552200510970; Bitencourt, Maria de Fátima Aparecida Saraiva; https://orcid.org/0000-0001-7022-9175; http://lattes.cnpq.br/0981121292868485; Medeiros, Walter Eugênio de; https://orcid.org/0000-0002-6757-0572; http://lattes.cnpq.br/2170299963939072The Acari Batholith stands out in the geological and metallogenetic evolution of the Seridó Belt both for its extension and facies diversity, as well as for the historical association of its northern portion, the Serra do Dorna Granite (SDG), with scheelite mineralization in the Brejuí-Boca de Laje District. However, the batholith's deep structure and thermobarometric evolution within the Seridó Belt context still require more detailed investigations. This study addresses these gaps through two main approaches. The first approach consists of 2.5D forward gravity modelling of the central-northern portion of the Acari Batholith, where negative gravity anomalies indicate its feeder zone. For this purpose, ten E-W oriented profiles with 2 km spacing were modeled using GM-SYS extensions in Seequent Oasis Montaj®. The second approach integrates petrographic and lithogeochemical aspects of the SDG granites, including 1:50,000-scale geological mapping to identify magmatic facies, field relationships, and structures. Thermobarometric estimates were performed based on whole-rock geochemical data. The SDG consists of equigranular to microporphyritic granites, while porphyritic granites and diorites predominate in the batholith's central portion. Gravity modelling results reveal two roots in the northeastern segment of the Acari Batholith, aligned in the NE-SW direction. The northern root is located outside the outcrop area, between the Acari Batholith and the Acauã Stock, at 1150 m depth. The southern root is deeper (1930 m) and lies beneath the batholith's outcrop area near Serra da Lagoa Seca. Although separated at the surface by a thin cover of mica schists, the Acari Batholith and Acauã Stock constitute the same magmatic system at depth. Thermobarometric estimates indicate crystallization temperatures between 909 and 702°C and pressures between 2.6 and 3.5 kbar, consistent with regional calibrations for the batholith's host mica schists. The maximum pressures represent an emplacement depth of 13.5 km, reflecting the depth reached by Seridó Group metasedimentary rocks during the peak of the D3 metamorphic-deformational event. The eastward displacement of the batholith's roots suggests a higher thermal gradient in this direction, whose influence is manifested in the hightemperature/low-pressure assemblages of the host mica schists (sillimanite + cordierite). In summary, the results demonstrate how the integration of gravity modeling and thermobarometry provides a more robust understanding of the Acari Batholith's structure and emplacement, as well as its relationship with the Seridó Belt's tectonometamorphic context.Master Thesis Estrutura térmica da Bacia de Barreirinhas, margem equatorial brasileira(Universidade Federal do Rio Grande do Norte, 2025-03-10) Fonseca, Chayane Vitória Felix; Castro, David Lopes de; https://orcid.org/0000-0003-1110-9389; http://lattes.cnpq.br/8279954644750743; http://lattes.cnpq.br/4932969319242823; Melo, Alanny Christiny Costa de; Xavier Neto, PedroThis study characterizes the thermal regime of the Barreirinhas Basin, located in the central sector of the Brazilian Equatorial Margin (BEM), based on 592 temperature records obtained from 85 exploratory wells, encompassing both onshore and offshore areas. Bottom-hole temperature (BHT), drill-stem test (DST), and extrapolated temperature (ET) measurements have been corrected using conventional methods, including the American Association of Petroleum Geologists (AAPG) and a Linear Fit methods, developed in this study. The AAPG method exhibited the best performance for BHT data (R² = 0.8463), while the Linear Fit Method showed consistent results in DST data correction. Corrected temperatures ranged from 45°C to 165°C across the Barreirinhas basin, associated with geothermal gradients from 19°C/km to 40°C/km. The geothermal gradient decreases sharply down to 800 m, stabilizing around 30°C/km and decreasing to 20°C/km at depths greater than 5,000 m. Thick sedimentary layers act as thermal insulators, limiting heat dissipation to the surface and reducing the geothermal gradient by the blanket effect. These thermal conditions indicate potential for liquid hydrocarbon generation between 1,500 and 3,500 m depth, whereas gas generation may occur at depths greater than 3,550 m. The correlation between the thermal regime and the internal architecture of the basin is consistent with patterns observed in Asian transform margins, as well in the conjugate African Equatorial Atlantic margin, reinforcing the relevance of the Barreirinhas Basin as a potential reservoir for energy resource production.Master Thesis O parâmetro resistência elétrica transversal e sua aplicabilidade ao estudo do Aquífero Barreiras no litoral sul do RN - análise qualitativa e composição em uma cartografia exploratória de transmissividade hidráulica(Universidade Federal do Rio Grande do Norte, 2025-01-29) Magalhães, Álvaro Luís Patriota Lima; Lucena, Leandson Roberto Fernandes de; http://lattes.cnpq.br/4673404543485023; http://lattes.cnpq.br/5281100883521840; Campos, Benedita Cleide de Souza; Stein, PaulaThe cities on the east coast of Rio Grande do Norte rely on the Barreiras Aquifer for about 80% of their water supply, which has a hydraulic character that is predominantly unconfined. In this context and considering the aforementioned water source, this research targeted two distinct areas: the first encompasses the Catu River basin in RN, and the second is located on the left bank of the Boa Cica Stream, in the municipality of Nísia Floresta-RN. Both areas are carved into the Cenozoic sequences of the Barreiras Formation and its coverings. The objective was to identify subareas with greater hydrogeological potential using geoelectric data. The methodology was based on local transverse electrical resistance (RT) parameter studies and its direct correlation with hydraulic transmissivity. In the Catu River basin area, the northeastern and central regions showed RT values higher than 50,000 Ohm.m², which are associated with sectors of thickness and/or average resistivities of the saturated zone, indicating these subareas as the most promising in terms of hydrogeological potential. The greatest average thicknesses of the saturated zone are located in the northeastern and central portions, reaching 95 meters, while the highest values of average resistivities of the saturated zone are in the central and extreme northeastern parts of the area, reaching 950 Ω.m. However, linear regressions revealed that the average saturated thickness has a greater influence on the calculation of transverse electrical resistance, with a correlation factor of 0.70, while the average resistivity factor was 0.47. The RT results for the left bank area of the Boa Cica Stream showed the highest values in the southern and western portions, reaching 58,860 Ωm², associated with zones of greater thickness and/or average resistivity of the saturated zone. In this regard, and in contrast to the results obtained in the Catu River basin area, the analysis of the predominant factor in the RT calculation, carried out through linear regression, revealed a predominance of the average resistivity parameter of the saturated zone, associated with hydraulic conductivity, showing a correlation factor (R²) of 0.89. Additionally, considering the direct proportionality with RT and through an aquifer test for geoelectric calibration in this area, a preliminary map of hydraulic transmissivities (T) was developed. The results support this methodology as promising in identifying higher hydraulic transmissivities and, consequently, hydrogeological potential, especially in regions with limited well information.Master Thesis Modelos de Q constante podem reproduzir a dispersão dependente da frequência dos sinais de GPR em rochas sedimentares(Universidade Federal do Rio Grande do Norte, 2025-02-27) Santos, Edilson Barauna dos; Xavier Júnior, Milton Morais; Marques, Manilo Soares; Xavier Neto, Pedro; Dantas, Renato Ramos da SilvaWe measured the complex dielectric constants of sandstone and carbonate samples from the Rio do Peixe and Potiguar basins, respectively presenting deformation bands and karstification features. The measurements were modeled using the Jonscher power-law model, which is able to represent the frequency-dependent behavior of these samples. We investigate the applicability of constant-Q models to describe the dispersion of Ground Penetrating Radar (GPR) signals in sedimentary rocks. GPR data is often affected by signal dispersion, which can make difficult the interpretation of events in GPR sections, especially in complex sedimentary environments. We then estimated an equivalent constant quality factor (Q) model, under the criterion of matching the frequency centroid shift of the GPR signal, using a line search approach. Equivalent Q estimates are possible to obtain using our approach, but they depend on the chosen propagation distances when the distances are small. Additionally, we obtain an analytical upper bound for the propagation distance that produces small phase shifts as a function of the Jonscher model parameters and the wavelength.Master Thesis Texturas e química mineral de zirconosilicatos em granitos peralcalinos do Pluton Papanduva, PR-SC(Universidade Federal do Rio Grande do Norte, 2024-08-23) Grangeiro, Larissa Praxedes; Vilalva, Frederico Castro Jobim; https://orcid.org/0000-0003-3399-6863; http://lattes.cnpq.br/6227637633613443; http://lattes.cnpq.br/3254967283599785; Rojas, Gaston Eduardo Enrich; Rosa, Pedro Augusto da SilvaElpidite (Na₂ZrSi₆O₁₅·3H₂O) and (Na,K)-zirconosilicates are zirconium-bearing minerals identified in the peralkaline granites of the Papanduva Pluton, located in the Graciosa Province in southern Brazil. These minerals crystallized during the late- to post-magmatic stages, providing insights into the formation and evolution processes in complex magmatic environments. Elpidite occurs in three distinct textural types: (1) isolated crystals with subhedral to euhedral forms, (2) granular aggregates, and (3) vein-like aggregates, each exhibiting specific compositional variations. Additionally, two phases of (Na,K)-zirconosilicates, designated as (Na,K)ZrS-I and (Na,K)ZrS-II, were identified, each displaying distinct textural and compositional properties. Chemical analysis reveals that elpidite has a predominantly uniform composition, with variations in Zr, Al, Ca, and K, aligning with the ideal end-member of elpidite. In contrast, (Na,K)-zirconosilicates are enriched in K relative to Na and exhibit diverse compositional trends. The (Na,K)ZrS-II phase shows greater compositional affinity with melansonite, whereas (Na,K)ZrS-I represents a transitional phase between lower and higher K end-members. However, elemental substitutions occurred within a limited range, suggesting the absence of a complete solid solution between these elements. Trace element analysis of elpidite revealed lower concentrations of most elements compared to zircon, including rare earth elements (REE), but with significant enrichments in Ba, Pb, and Sr. The textural relationships and compositional data of zirconosilicates from the Papanduva Pluton suggest a complex evolution of these minerals, reflecting a transition from less evolved rocks, where zircon predominates as the zirconium carrier, to more evolved rocks. Elpidite likely formed during the late magmatic stages, followed by the development of granular and vein-like varieties. Interaction with K-rich hydrothermal fluids, possibly facilitated by sub-magmatic deformation, resulted in significant hydrothermal alteration, chemical remobilization (including HFSE and REE), and element incorporation, forming (Na,K)ZrS-I and (Na,K)ZrS-II phases from a precursor zirconosilicate, ideally elpidite, or directly from the fluids. This transition is associated with increased peralkalinity (alkali activity), oxygen fugacity, and variation in water content, favoring the stabilization of zirconosilicates as zirconium-bearing phases.Master Thesis Histologia óssea e diagênese fóssil de smilodon populator e puma concolor (carnivora: felidae) do pleistoceno do Brasil equatorial(Universidade Federal do Rio Grande do Norte, 2024-11-22) Maciel, Virgínia Silva; Ghilardi, Aline Marcele; Aureliano Neto, Tito; https://orcid.org/0000-0002-6918-0519; http://lattes.cnpq.br/3666297020355529; https://orcid.org/0000-0001-9136-0236; http://lattes.cnpq.br/5761534317977568; http://lattes.cnpq.br/4943881100446288; Castro, Mariela Cordeiro de; Araújo Júnior, Herminio Ismael deLarge felids have been one of the groups most impacted by climate change over the last 50,000 years. By comparing palaeobiological aspects of extinct species with those of living species, it is possible to identify possible reasons for extinction selectivity and even describe how species were affected by environmental changes in the past. Understanding these issues is fundamental to understanding the risk that current species face in the face of ongoing climate change. In this study, the femur histology of Smilodon populator (MCC-868V) and a fossil specimen of Puma concolor (MCC-991V) were sampled, both from Quaternary deposits in Rio Grande do Norte, northeastern Brazil, one from a tank and the other from a cave. In addition, estimates of body mass were made for the specimens analysed to compare with bone compactness, and the diagenetic signatures of both specimens were analysed. The presence of EFS (External Fundamental System), generations of secondary osteons and remodeled bone tissue suggest that the individuals analysed were sexually mature, although MCC-868V was a young adult at the time of death and MCC-991V a senescent adult. P. concolor showed slightly greater bone compactness, which may be related to its more advanced ontogenetic stage. The estimated mass for the P. concolor (62 kg) is within the limits observed for the species. However, the estimated mass for S. populator (157 kg) is lower than expected, even though the specimen analysed was an adult with closed growth. There is no histological evidence that the specimen in question was restricted during its growth, suggesting a naturally smaller individual, a trait that may have been selected in a local population due to the specific environmental and ecological conditions of the region and/or the presence of competition with other carnivore(s). Both specimens analysed showed growth with intense secondary remodelling, which differs from what is known for most tetrapods. The extinction of Smilodon is likely more related to ecological aspects, such as a reduction in prey availability or preferred habitat than physiological aspects. Finally, MCC-868V shows diagenetic fractures filled with oxides that break up histological structures and the presence of quartz grains in the bone trabeculae. MCC-991V, on the other hand, shows evidence of recent weathering and the presence of oxide precipitates. The diagenesis of the specimens analysed is very similar to that found in other fossils from the same deposits, which adds to the understanding of the fossilization processes involved in tank and cave deposits in equatorial regions.Master Thesis Integração de dados radiométricos e petrográficos de plutons ediacaranos para detalhamento de mapeamento geológico no domínio Rio Piranhas-Seridó, extremo NE da Província Borborema(Universidade Federal do Rio Grande do Norte, 2024-11-28) Dias, Marília Cristina Santos Souza; Nascimento, Marcos Antônio Leite do; http://lattes.cnpq.br/5356037408083015; http://lattes.cnpq.br/9527786124074381; Vilalva, Frederico Castro Jobim; https://orcid.org/0000-0003-3399-6863; http://lattes.cnpq.br/6227637633613443; Guimarães, Suze Nei PereiraRadiometry is a shallow geophysical investigation method based on the emission of natural gamma radiation from rocks, which aids in identifying lithotypes and lithologicalcontacts. The qualitative interpretation of radiometric data allowed for the characterization of the main signatures of the shoshonitic, high-potassium calc-alkaline porphyritic, high-potassium calc-alkaline equigranular, calc-alkaline suites associated with Ediacaran magmatism (635 – 541 Ma) in the northeastern edge of the Borborema Province. Four plutons were highlighted as target areas: i. Acari; ii. Totoró; iii. São Rafael; and iv. Serrada Garganta. Data from the potassium channels (K in %), equivalent thorium (eTh in ppm), equivalent uranium (eU in ppm), and ternary radiometric composition RGB (red, green, and blue) were used to delineate radiometric domains in a GIS environment. Thesedomains represent closed polygons where the distribution pattern of K, eTh, and eU radioelement contents is classified as low (1), medium (2), and high (3). Interpretation maps for each target area were created based on the 27 possible color combinations in the RGB pattern. The mineralogical composition of the granites, which are mainly composed of quartz, feldspars (plagioclase and microcline), and micas (biotite and muscovite), favors generic K-rich signatures. Additionally, the texture of these granites (grain size and crystal orientation) affects the distribution of these elements. A pattern predominantly showing high values for K and eTh is observed in rocks belonging to the high-potassium calc-alkaline porphyritic (Itaporanga type), alkaline (Conceição type), and highpotassium calc-alkaline equigranular (Dona Inês type) suites. However, the texture of these rocks also influences this analysis, as porphyritic granites tend to highlight K values in relation to eTh and eU content due to the size of the K-feldspar crystals. Nevertheless, regions mapped as the Itaporanga Intrusive Suite that exhibit low to medium patterns in radioelements can be explained by the interference of lenses of dioritic rocks, metasedimentary rocks, terrigenous quartzose sediments, as well as water bodies. For the São João do Sabugi Suite, a predominant pattern of low values for the radioelements was observed, attributed to the mineralogical composition of the rocks in this suite, characterized by the low representation of K, eTh, and eU-rich minerals, with a predominance of biotite and amphibole.Master Thesis Modelagem de reservatórios fraturados e carstificados usando afloramento análogo de alta resolução e análise de sensibilidade de cenários simulados(Universidade Federal do Rio Grande do Norte, 2024-03-04) Corrêa, Simone Nabuco; Bezerra, Francisco Hilario Rego; https://orcid.org/0000-0002-3512-5212; http://lattes.cnpq.br/6050302316049061; http://lattes.cnpq.br/3997804295045931; Perez, Yoe Alain Reyes; Erthal, Marcelle Marques; Vasconcelos, David Lino; Borges, Sérgio Vieira FreireThis study presents a multidisciplinary workflow to improve understanding of fractured and karstified carbonate reservoirs. The study seeks to uncover geological mechanisms behind fracturing and karstification by integrating analog outcrop fieldwork with regional correlation. This knowledge is crucial for constructing more accurate geological models and improving the management of these complex reservoirs. We use the Jandaíra Formation in the Potiguar Basin, Brazil, as an analog for fractured and karstified carbonate reservoirs. Our results focus on the Furna Feia cave, characterized by dissolution dome structures and NW-SE-trending conduits. Regional stratigraphic analysis identified lithofacies patterns and correlated system tract cycles to map more karstified layers, relating the cave formation to the SB-2 unconformity. Structural analysis revealed that rift faults, caves, and fractures are oriented NW-SE and NE-SW. The regional 3D geological model, covering an area of 30x14 km with 179 layers, integrates data from two wells, interpreted surfaces, fracture models (DFN), and karst features, revealing intensely dissolved layers between the SB-1 and SB-2 unconformities. Building upon this, we propose a new approach to karst modeling that combines conduits and karstified fractures following a comprehensive conceptual model. Four models were simulated to evaluate the water and oil production history, similar to analog carbonate reservoirs. We concluded that including karst and fractures improves performance, increasing production, but it affects some wells due to premature water breakthroughs. Therefore, effective management and optimized planning for wells are essential for reservoirs containing karst and fractures. This multidisciplinary workflow, from creating geological models to reservoir simulation, assesses different scenarios, providing insights into potential outcomes and associated risks that would influence decision-making in production development projects.Master Thesis Aplicação de aprendizado de máquina para estimativa da permeabilidade utilizando dados de RMN de rochas análogas a reservatório(Universidade Federal do Rio Grande do Norte, 2024-08-19) Mafra, Mauricio Gabriel Lacerda; Xavier Júnior, Milton Morais; http://lattes.cnpq.br/3128669965557866; https://orcid.org/0000-0003-2720-4655; http://lattes.cnpq.br/7598665592966289; Marques, Manilo Soares; Souza, André Alves deThis master's thesis explores the relevance of studies on rocks analogous to reservoirs, with a primary focus on the petrophysical permeability parameter. Traditional petrophysical techniques provide absolute values for this parameter but offer limited insights into the underlying reasons for these values. The absence of precise information necessitates the use of more advanced techniques for a systematic reservoir analysis. While Nuclear Magnetic Resonance proves effective in obtaining advanced reservoir information, its analytical models for permeability lack accuracy, particularly in heterogeneous reservoirs, revealing certain limitations. Filling this gap, this study aims to improve permeability predictions by employing machine learning models such as Random Forest, Gradient Boosting, and Multi-Layer Perceptron. The goal is to predict permeability based on patterns obtained through Nuclear Magnetic Resonance, compare them with analytical models, and identify the model that best suits the reservoir. It was observed that machine learning models provided more accurate predictions compared to analytical models.Master Thesis Produção de calor radiogênico de granitoides ediacaranos do Extremo Nordeste da Província Borborema(Universidade Federal do Rio Grande do Norte, 2024-02-22) Azevedo, Luanna Celly Silva de; Vilalva, Frederico Castro Jobim; https://orcid.org/0000-0003-3399-6863; http://lattes.cnpq.br/6227637633613443; http://lattes.cnpq.br/3893969676847490; Florisbal, Luana Moreira; https://orcid.org/0000-0001-6580-5828; http://lattes.cnpq.br/2412442370169089; Guimarães, Suze Nei Pereira; https://orcid.org/0000-0002-0867-1058; http://lattes.cnpq.br/3950034549217657The study examines the Ediacaran-Cambrian plutonic magmatism within the Rio Piranhas-Seridó (PSD) and São José do Campestre (JCD) Domains (NE Borborema Province, Brazil), with a focus on the radiogenic heat production (A) of granitoids. This magmatism encompasses a variety of batholiths, plutons, stocks, and dikes, with distinct petrographic and chemical features, grouped into six plutonic suites. The radiogenic heat production was investigated and compared with petrographic and chemical characteristics of the granitoids from the High-K Calc-Alkaline (porphyritic and equigranular) and Shoshonitic suites, encompassing syeno-monzogranites to monzodiorites, and gabbros/diorites, with metaluminous to peraluminous compositions and calc-alkaline to alkaline signatures. The high-K calc-alkaline porphyritic granitesregister higher A values (up to 11.7 μW/m³) due to high concentrations of Th and U, in contrast to the lower values in shoshonitic rocks (up to 3.5 μW/m³). There is a positive correlation between A, SiO2, and the modified alkali-lime index (MALI), suggesting that more evolved and alkaline compositions favor higher heat generation. The mean Th/U ratio for all suites is 8.6, exceeding typical crustal values. The studied rocks were classified into low (LHP), medium (MHP), and high (HHP) heat production groups. The JCD samples mainly correspond to LHP and MHP, whereas those from the PSD include all categories, with HHP restricted to calc-alkaline granites and shoshonites limited to the LHP group. The spatial distribution of A and the concentrations of Th, U, and K indicate areas within the PSD with geothermal potential for further investigationsMaster Thesis Caracterização e evolução de sistemas de ilhas barreiras tropicais no litoral de Macau, estado do Rio Grande do Norte, NE do Brasil(Universidade Federal do Rio Grande do Norte, 2023-11-30) Rocha, Dhulya Rafaelly das Chagas; Vital, Helenice; http://lattes.cnpq.br/3595069999049968; http://lattes.cnpq.br/1324455359155262; Nogueira, Mary Lucia da Silva; http://lattes.cnpq.br/2546229173660779; Almeida, Narelle Maia deThe northern coast of the state of Rio Grande do Norte is classified as a mixed-energy tropical coast and presents a very intense coastal dynamic. Within this context is outstanding the presence of barrier island-spits system, end members of sandy bodies parallel to the coastline, which isolate protected areas from the impact of the open sea. The barrier island-spits systems stand out for having different sedimentary deposits on their marine and terrestrial sides. In this perspective, the characterization and analysis of this system, having the knowledge about the processes that act in these environments and their sedimentary/stratigraphic configuration is of utmost importance for both environmental studies and oil and gas reservoir analogues. The main objective of this study was the characterization of the barrier island-spit systems of the northern coastline of the state, near the city of Macau, RN. The research includes data from bathymetry of tidal channels, surface samples and vibracores collected from sub-environments of the barrier island-spit system. The results indicated channels with depths ranging from 1.3 to -6.3 meters, and the main channel having a 'U' shape. Sandy/muddy banks were identified along the channel margins, as well as two areas featuring 2D and 3D underwater dunes, varying in size from small to large. Six sedimentary facies association interpreted in the cores were associated with tidal channel deposits, tidal flat, tidal inlet shoal, beach/barrier island, aeolian sand and washover. The similarity between the features of the surface samples and the facies described in the cores assisted in the interpretation of the sub-environment associated with each facies association.Master Thesis Aplicação de simulação numérica e aprendizado profundo utilizando imagens de micro-ct de rochas reservatório(Universidade Federal do Rio Grande do Norte, 2024-05-23) Kiam, Thiago Noboru Leite; Xavier Júnior, Milton Morais; http://lattes.cnpq.br/3128669965557866; http://lattes.cnpq.br/8176148304942096; Lucena, Leandson Roberto Fernandes de; http://lattes.cnpq.br/4673404543485023; Marques, Manilo Soares; Soares, José AgneloCarbonate rocks constitute important reservoirs of mineral resources, however, they exhibit a high degree of anisotropy and heterogeneity, with various types of pores and scales that challenge both the industry and the scientific community. Digital petrophysical studies aim to obtain intrinsic rock parameters through the 3D rendering of X-ray microtomography images. The present study aims to classify pore types and estimate petrophysical parameters from the 3D rendering, segmentation, and numerical simulation of images of carbonate rocks from the Jandaíra Formation, Potiguar Basin, Rio Grande do Norte, Brazil. The images were acquired by X-ray microtomography, with resolution of 35 μm, and represent transverse slices of the rocks. For the treatment of slices, the ImageJ program was used. The segmentation of 3D pores was performed using the multi-Otsu method with the Simpleware ScanIP software. The segmented files were discretized and imported into the Comsol Multiphysics numerical simulator with coarse mesh density. The simulator adopts the finite element method (FEM) to perform its calculations. The simulated physics was configured to be a single-phase fluid in steady-state, laminar flow, with a density of 1000 kg/m³ and a viscosity of 0.001 Pa.s. The differential pressure between the inlet and outlet of this fluid was established at 1 Pa. Comparing with literature and laboratory-obtained values, the digital results were satisfactory and consistent. Segmentation enabled the classification of well-developed stylolites and vugs among the samples. Petrophysical estimates ranged from 0.70% to 7.99% with effective porosity and simulated permeability ranged from 7.79 mD to 3000 mD. Regarding deep learning, the Alexnet model, with SGD criterion and MSE optimizer, exhibited the best performance.