Programa de Pós-Graduação em Geodinâmica e Geofísica
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Doctoral Thesis Zonas de falhas com bandas de deformação e silicificação hidrotermal: caracterização estrutural e petrofísica(Universidade Federal do Rio Grande do Norte, 2025-12-22) Palhano, Leonardo Carvalho; Bezerra, Francisco Hilário Rego; Nogueira, Francisco Cezar Costa; https://orcid.org/0000-0002-3512-5212; https://orcid.org/0009-0005-3028-6710; Menezes, Cristiane Paulino de; Strugale, Michael; https://orcid.org/0000-0003-1106-7529; Borges, Sérgio Vieira Freire; La Bruna, Vincenzo; https://orcid.org/0000-0002-1250-8667This research investigates hydrothermal silicification and the presence of deformation bands (DBs) in a damage zone, with a focus on their impact on petrophysical and geomechanical properties in sandstones. In addition, we investigate how the tectonic regime influences the development and deformation processes that give rise to DBs, highlighting their effects on petrophysical properties. Hydrothermal silicification and DBs significantly influence the physical properties and fluid flow behavior of porous siliciclastic rocks. However, their combined effects within fault zones remain poorly constrained. This study integrates structural, microstructural, geomechanical, and petrophysical analyses to investigate how silicification and DBs kinematics impact reservoir-quality parameters in fault zones from the Rio do Peixe Basin (RPB) and Jatobá Basin (JB) in northeastern Brazil. In the RPB, quartz cementation is confined to a halo around the fault, defining three main silicification zones: (1) non-silicified sandstone, (2) moderately silicified sandstone, and (3) intensely silicified sandstone. Silicification, sourced from both external silica influx and feldspar dissolution, drastically reduces porosity and permeability by up to four orders of magnitude while increasing uniaxial compressive strength by one order. Cement precipitation also occurs within DBs, further decreasing pore connectivity and fluid flow capacity. In the JB, DBs formed under sequential extensional and contractional regimes display contrasting microstructural and petrophysical characteristics. Normal-sense DBs, dominated by shear and grain breakage, exhibit the highest cataclastic matrix content and the lowest porosity (0.21%) and permeability (0.41 mD). Conversely, reverse-sense DBs, shaped by compactional processes, retain higher porosity (2.21%) and permeability (142.4 mD). The tectonic regime thus exerts a fundamental control on deformation mechanisms, cataclasis intensity, and fluid flow behavior. Overall, the integration of silicification and deformation processes reveals that both chemical and mechanical modifications within fault zones critically affect sandstone reservoir quality, promoting significant heterogeneity and compartmentalization that must be accounted for in flow modeling of structurally complex siliciclastic systems.Doctoral Thesis Estratigrafia de sequências e isotópica do cretáceo superior das bacias de barreirinhas e Pará-Maranhão, margem equatorial brasileira(Universidade Federal do Rio Grande do Norte, 2025-09-29) Medeiros, Ana Karoliny Alves de; Córdoba, Valéria Centurion; https://orcid.org/0000-0002-1836-4967; https://orcid.org/0000-0002-2053-3491; http://lattes.cnpq.br/4012969039515622; Figueiredo, Milene Freitas; Souza, Ana Clara Braga de; https://orcid.org/0000-0002-8514-9589; Sousa, Debora do Carmo; Lima Filho, Francisco Pinheiro; https://orcid.org/0000-0001-5657-5207The Brazilian Equatorial Margin (BEM) comprises a region of new hydrocarbon exploration frontier. The detailed knowledge of its evolution, tectonic processes and stratigraphic framework is fundamental for the determination of its petroleum potential. In this context, the present research aims to elaborate an environmental reconstitution of the time slice corresponding to the Upper Cretaceous of the Barreirinhas and Pará-Maranhão basins, inserted in the tectono-stratigraphic context of the BEM. For this, results of isotopic analysis with emphasis on stable isotopes of Carbon, Oxygen and Sulfur were used supported by the stratigraphic interpretation of well data (1D) and 2D and 3D seismic surveys. The integration of these data in the study of the evolution of BEM is relevant because isotopic stratigraphy is a powerful tool of stratigraphic analysis characterized by good sensitivity to paleoenvironmental variations, showing itself applicable in the face of possible mistakes, absences and/or limitations of conventional methods. The analysis of the Upper Cretaceous in the 1D data integrated with the seismic analysis allowed the individualization of 5 sequences composing the studied interval. The first one, called D1 Sequence, begins at the Break-up Unconformity and extends to the Cenomanian Unconformity, and can be subdivided into two other higher-order sequences, D1A and D1B. The most basal sequence (D1) is characterized by an isotopic signature compatible with periods of higher organic productivity, warmer temperatures and lower potential for preservation of organic matter. D2 Sequence, younger, goes from the Cenomanian Unconformity to the Turonian Unconformity, standing out from the others for presenting less negative isotopic signature among the entire study interval. It is in this sequence that the samples with the most enriched results in the heavy isotope are found and, therefore, present a possible greater potential for preservation of organic matter. Still in D2 Sequence is interpreted the most important anoxic event of this time slice. Like the global anoxic event recognized and mapped in the literature, this event occurs precisely between the end of the Cenomanian and the beginning of the Turonian, called OAE-2 (Oceanic Anoxic Event-2). Therefore, it can be concluded that within the D2 Sequence there is a Marine Flooding Surface (MFS), well-marked and identified in 1D data with the aid of the δ 13C ‰ (VPDB) and δ 34S ‰ (V-CDT) isotope ratio variation curves in the shales. Lithostratigraphically, this interval also corresponds to the deposition of the Travosas Formation, represented by shales with intercalation of Areinhas Formation sandstones, which may therefore indicate the occurrence of a more favorable interval for hydrocarbon accumulation mainly in the form of turbidite deposits. The next sequence, named D3, occurs from the Turonian Unconformity to the Campanian Unconformity. It is characterized by isotopic behavior compatible with negative excursions of δ 13C ‰ (V-PDB) at the sequence bottom, which vary towards the top until they become more enriched values. Thus, it is towards the top that this sequence begins to show a better trend of organic matter preservation, where another important MFS can also be identified. Going from the Campanian Unconformity to the Maastrichtian Unconformity, D4 Sequence maintains the trend of D3 Sequence of increasing the potential for preservation of organic matter progressively towards its upper limit, becoming less negative, and ending with a drop in these values. Finally, D5 Sequence marks the transition from the Cretaceous to the Palaeogene System, presenting an isotopic signature compatible with a drop in organic productivity and organic matter preservation potential, followed by cooling and warmer temperatures, as a reflection of global variations.Doctoral Thesis Interpretação sismoestrutural de um subvolume sísmico no Campo de Pitu, Bacia Potiguar offshore(2025-12-17) Araújo, Alinne Jéssica Dantas de; Antunes, Alex Francisco; https://orcid.org/0000-0002-3292-4190; Sousa, Debora do Carmo; Silva, Fernando Cesar Alves da; Pichel, Leonardo Muniz; https://orcid.org/0000-0001-8692-3831; Rodrigues, Ricardo de SouzaThe tectonic evolution of the Potiguar Basin has traditionally been interpreted as the result of two rifting stages integrated into a single evolutionary trajectory. However, divergences persist regarding the understanding of these phases in terms of tectonic regime and basin evolution, especially given the use of the terms “onshore” and “offshore” for distinct structural domains. In this thesis, the integrated analysis of 3D seismic data and well information allowed these interpretations to be revisited and a reinterpretation of the architecture of the rift system to be proposed. The results indicate that the two rifting events correspond, in fact, to distinct tectonic systems— here termed Potiguar I and Potiguar II—and not internal phases of a single basin. Structural mapping reveals that the analyzed area shows no evidence of faults attributable to the first rifting episode, being dominated by structures compatible with the second event, affecting the Pendência, Pescada, and Alagamar formations. This observation implies a revision of the placement of the Alagamar Formation, often described as post-rift based on records from the onshore portion. In the analyzed data, tectonic activity contemporaneous with its deposition is observed, suggesting a late syn-tectonic character in the Potiguar II domain, whereas in the Potiguar I domain the unit retains a post-tectonic character. This differentiation aligns with discussions regarding the existence of a transitional sequence between the rift and post-rift (breakup), for which the Alagamar Formation displays consistent attributes. The application of seismic attributes and filters contributed to the detailed recognition of structural discontinuities, allowing refinement of fault patterns and internal heterogeneities of the basin. In summary, the results obtained demonstrate that the tectonic evolution of the Potiguar Basin is more segmented than suggested by classic regional models. The distinction between Potiguar I and Potiguar II provides a more robust framework for understanding its evolution and contributes to advancing discussions on the complexity of the equatorial margins of the South Atlantic. The results also open possibilities for further investigations, particularly regarding integration with sedimentary data and regional comparisons along the Brazilian Equatorial Margin.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.Doctoral Thesis Estudo de complexos turbidíticos e sistemas petrolíferos associados nas bacias marginais do setor central da margem equatorial brasileira(Universidade Federal do Rio Grande do Norte, 2025-12-23) Goulart, José Paulo de Melo; Castro, David Lopes de; Melo, Alanny Christiny Costa de; https://orcid.org/0000-0002-6413-3609; https://orcid.org/0000-0003-1110-9389; https://orcid.org/0009-0000-7414-4523; Tavares, Aline Cristine; https://orcid.org/0000-0002-8132-268X; Gomes, Moab Praxedes; https://orcid.org/0000-0003-0836-1073; Xavier Neto, Pedro; Mohriak, Webster UeipassSedimentary basins in new exploration frontiers are considered high-risk exploration areas. Increasing the chances of success is one of the main objectives of a hydrocarbon exploration company, especially in a frontier basin such as the Barreirinhas basin. One of the main objectives of this work is to increase the chances of success by revealing exploration opportunities with Direct Hydrocarbon Indicators (DHIs) and with sufficient area to generate an economic accumulation, through the study of seismic attributes. Seeking to reduce these risks, 5,450 km of 2D seismic lines were interpreted in the central sector of the Brazilian Equatorial Margin, in the Barreirinhas Basin, focusing on mapping structures similar to those found in the giant fields of the West African margin, which also had Direct Hydrocarbon Indicators (DHIs) and could be validated by seismic attributes, which are powerful tools in monitoring and predicting the presence of hydrocarbon zones. Seismic attributes such as Chaos, Root Mean Square (RMS) Amplitude, Instantaneous Amplitude or Envelope, Instantaneous Phase, and Apparent Polarity were generated and enhanced in terms of quality, which helped identify seven exploratory opportunities in this sedimentary basin. Three special frequency attributes were also used to highlight the low and high frequencies of the seismic signal. The LFE (Low Frequency Enhancement) attribute enhances low frequencies, facilitating the mapping of gas chimneys whose strongest amplitudes lie in this frequency range. The HFE (High Frequency Enhancement) attribute favors the visualization of high frequencies, increasing vertical seismic resolution and allowing the mapping of thin reservoirs. The third attribute was LHFE (Low and High Frequency Enhancement), combines the two previous attributes and facilitates the mapping of turbidites, faults, gas chimneys, and other IDHs, thereby providing more reliable interpretation. The survey revealed three turbidite complexes, identified and verified using frequency attributes, which greatly reduced exploration risk. Seven exploration opportunities were also mapped, clearly highlighting the presence of IDHs emphasized in their seismic images by the various attributes obtained in Petrel E&P Software Platform.Doctoral Thesis Batimetria com sensores ópticos: proposta metodológica e aplicações na margem equatorial brasileira(Universidade Federal do Rio Grande do Norte, 2025-04-29) Silva, Filipe Ezequiel da; Vital, Helenice; https://orcid.org/0000-0003-0462-9028; http://lattes.cnpq.br/3595069999049968; http://lattes.cnpq.br/7618228165680475; Gomes, Moab Praxedes; https://orcid.org/0000-0003-0836-1073; http://lattes.cnpq.br/2086362176219605; Nogueira, Mary Lucia da Silva; http://lattes.cnpq.br/2546229173660779; Silva, André Giskard Aquino da; http://lattes.cnpq.br/5175466944684146; Souza Filho, Pedro Walfir Martins e; https://orcid.org/0000-0003-0252-808X; http://lattes.cnpq.br/3282736820907252Among the many applications of orbital remote sensing, bathymetric data collection offers a unique advantage by enabling the analysis of the Earth's surface in threedimensions. This expanded perspective allows for more effective modeling of geomorphological features and facilitates the assessment of their temporal dynamics. In coastal regions - and particularly within shallow marine environments - optical sensors have proven highly effective in the digital seabed modeling, thereby expanding knowledge in areas where conventional data acquisition methods are often logistically challenging, costly and associated with elevated-risk. Within the Brazilian Equatorial Margin (MEB), satellite derived bathymetry remains underutilized, despite the region’s high potential and the increasing demand for detailed seafloor information. This study aimed to develop a methodological framework and implement established techniques of satellite-derived bathymetry (SDB) using optical sensors to map the northern continental shelf of the State of Rio Grande do Norte, located in the semiarid sector of the MEB. The proposed methodology involved quantifying the volume of sediment remobilization in sandy spits through the generation and analysis of beachface profiles derived from Planet SuperDove sensor imagery. This approach enabled the effective monitoring of a sandy spit progradation, which resulted in the accumulation approximately 150,000 m³ of sediment (with a mean thickness of 1.76 m) over a 472-day interval. In optically clear waters, empirical bathymetry derived from satellites were applied using Sentinel 2 MSI imagery, incorporating logarithmic band ratio equations and multiple linear regressions techniques. The most robust models exhibited high representativeness (R²=0.92) for depths up to 15 meters, with vertical accuracy on the order of 1.1 meters. These findings demonstrated the efficacy and reliability of the applied SDB methods, which are consistent with analogous approaches documented in scientific literature. According, the methodology is recommended for applications in other sectors of the MEB, contributing to the advancement of regional marine geospatial analysis.Doctoral Thesis Evolução tectono-estratigráfica da seção cretácea na Bacia de Barreirinhas, Margem Equatorial Brasileira(Universidade Federal do Rio Grande do Norte, 2025-09-30) Rapozo, Bárbara Ferreira; Córdoba, Valéria Centurion; https://orcid.org/0000-0002-1836-4967; http://lattes.cnpq.br/8212523609187259; http://lattes.cnpq.br/1735852626118012; Figueiredo, Jorge de Jesus Picanço de; https://orcid.org/0000-0002-6989-7456; http://lattes.cnpq.br/6987738778276571; Silva, Carlos César Nascimento da; http://lattes.cnpq.br/5136096872133075; Morais Neto, João Marinho de; https://orcid.org/0000-0002-5930-1356; http://lattes.cnpq.br/9637521130587885; Pérez, Yoe Alain Reyes; https://orcid.org/0000-0003-2355-7533; http://lattes.cnpq.br/8835402837157614The basins of the Brazilian Equatorial Margin (BEM) have received increasing attention due to hydrocarbon discoveries in their African conjugate counterparts. The Barreirinhas Basin, although presenting high exploratory potential, still shows significant gaps in the understanding of its tectonostratigraphic evolution. This study analyzes the structural and stratigraphic framework of the onshore portion and shallow platform during the Cretaceous, through the integration of 2D seismic data, well geophysical logs, and previously published gravity data. The tectonostratigraphic characterization was based on the mapping of major unconformities and the application of sequence stratigraphy concepts, allowing the evaluation of the relationship between tectonic activity and depositional systems. The rift section was subdivided into five seismic-stratigraphic units, defined by the analysis of seismic facies, reflector terminations, and intra-rift unconformities. Lithostratigraphic and chronostratigraphic data from wells provided additional support for the calibration and validation of the interpretations. The seismicstructural analysis enabled the identification of grabens, half-grabens, and horsts, bounded by high-angle normal faults predominantly associated with the rifting stage and controlled by heterogeneities of the crystalline basement, with orientations ranging from E–W to NW–SE. In the context of the evolution of the Barreirinhas Basin pull-apart system, depocenters related to Rift Phases I (late Barremian to late Aptian), II (late Aptian to early Albian), and III (early Albian to late Albian) were analyzed. The construction of regional sections (transects) allowed the visualization and understanding of stratigraphic relationships critical to the regional context of the Barreirinhas Basin, which was directly influenced by the Romanche Fracture Zone (RFZ), imprinting transtensional structures as the dominant regime and transpressional features subordinately.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.