Programa de Pós-Graduação em Geodinâmica e Geofísica
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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.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.Doctoral Thesis Morfoestrutura da Cordilheira Meso-Oceânica entre as Zonas de Fraturas Marathon e 8°48'N(Universidade Federal do Rio Grande do Norte, 2025-01-08) Oliveira, Patrícia Reis Alencar; Gomes, Moab Praxedes; https://orcid.org/0000-0003-0836-1073; http://lattes.cnpq.br/2086362176219605; https://orcid.org/0000-0001-9647-7994; http://lattes.cnpq.br/0660553422919475; Vasconcelos, David Lino; Nogueira, Mary Lucia da Silva; Almeida, Narelle Maia de; Araújo, Tereza Cristina Medeiros deThe Mid-Atlantic Ridge is a highly complex geotectonic region, essential for understanding the evolution of oceanic crust and the processes associated with divergent plate tectonics. This study analyzed approximately 400 km of the ridge’s axial segment, between the Marathon Fractures Zone and 8°48’N, with depths ranging from 1,600 m to 6,000 m, using bathymetric, gravimetric, and seismicity data. The objective was to investigate the interaction between magmatism and tectonism in shaping the oceanic relief, with an emphasis on ridge-transform intersections (RTIs) and non-transform discontinuities (NTDs). The northern portion of the area, located above the Vema Fracture Zone, was divided into two supersegments, 12°N and 11°N, the latter further subdivided into the 11°55'N and 11°20'N segments. The southern portion presented the 9°N and 10°N supersegments, segmented by second-order discontinuities. The results indicate that these segmentations exhibit peculiar morphological and geophysical characteristics but share similar formation and evolution processes, highlighting how the interaction between magmatism and tectonism directly influences the morphotectonic configuration of the Mid-Atlantic Ridge. Structures such as detachment faults in elevated inside corners play a crucial role in generating asymmetries, reflecting the impact of lithospheric decoupling in slow-spreading regions with evidence of reduced magmatic flow. Additionally, NTDs promote reduced or absent magmatism, exposing massifs and rocks with altered rheology, distinct from those observed in the abyssal hills of the supersegments. These features, in particular, are favorable for fluid percolation and the formation of hydrothermal systems, standing out as priority areas for future investigations, especially at the intersection of the 11°20'N segment with the Vema transform fault.