https://repositorio.ufu.br/handle/123456789/20867 2026-09-25T22:19:35Z 2026-09-25T22:19:35Z https://repositorio.ufu.br/handle/123456789/50164 2026-09-10T06:21:20Z 2026-07-30T00:00:00Z

Title: Evolução sedimentar e reconstrução paleoambiental da porção sul do Complexo Deltaico do Rio Paraíba do Sul (CDRPS), litoral norte do Estado do Rio de Janeiro Abstract: The Paraíba do Sul Deltaic Complex (PSDC), located along the northern coast of Rio de Janeiro State, southeastern Brazil, within the emerged portion of the Campos Basin, records the Quaternary coastal evolution and constitutes an important sediment storage area, making it a region of significant scientific interest. Although it has been investigated since the 1940s, only recent studies based on deep borehole data have revealed its lithological and paleoenvironmental complexity, particularly within the youngest deposits controlled by relative sea-level fluctuations and the evolutionary phases of the Paraíba do Sul River. In the southern sector of the PSDC, where an extensive Pleistocene beach-ridge plain occurs, the lack of robust integration among the available datasets still limits the understanding of the depositional architecture, spatial distribution, and genesis of these deposits. In this context, the present study aims to compile, reinterpret, and integrate subsurface data from boreholes and Ground Penetrating Radar (GPR) sections available in the literature in order to reconstruct the paleoenvironments and develop a stratigraphic model based on sequence stratigraphy. The reinterpretation of borehole data enabled the identification of seven sedimentary facies (A, Ab, Ah, Aa, Aab, Ar, and Arb), grouped into four facies successions: SF-M (marine), SF-FE (fluvioestuarine), SF-CA (beach-ridge plain), and SF-F (fluvial), whose spatial relationships were analyzed through strike and dip correlation sections. The correlation sections reveal pronounced spatial heterogeneity in the distribution of the deposits, highlighting lateral facies changes associated with variations in depositional energy and sedimentary processes. The spatial distribution and vertical relationships among the facies successions indicate that the Quaternary evolution of the study area was controlled by relative sea-level fluctuations, alternating between transgressive phases, forced regression (fluvial incision), and coastal progradation accompanied by the development of beach ridges arranged in clinoforms. The integration of GPR data corroborated the progradational geometry of the beach ridges, whereas the spatial analysis suggested that the irregular beach ridges along the margins of Lagoa Feia are associated with a barrier responsible for the closure of an older inland lagoonal system, in contrast to the younger and more regular beach ridges located near the present-day coastline. The proposed model reveals a heterogeneous depositional architecture resulting from the interaction of marine, fluvio-estuarine, and fluvial processes through time, contributing to a better understanding of the Quaternary evolution of the emerged portion of the Campos Basin.

2026-07-30T00:00:00Z https://repositorio.ufu.br/handle/123456789/50131 2026-09-05T06:21:25Z 2026-07-28T00:00:00Z

Title: Geologia do granito Boa Esperança, setor Noroeste do complexo Monte Carmelo, Grupiara–MG Abstract: This study presents the geological characterization of the northwestern portion of the Monte Carmelo Complex (MCC) batholith, located near the municipality of Grupiara (MG), focusing on the individualization and evolutionary understanding of the Boa Esperança Granite. The methodology integrated a bibliographic review, previous geological data compilation, remote sensing using a Digital Elevation Model (DEM), and airborne geophysical mapping based on gamma-ray spectrometry data (individual K, U, and Th channels and RGB ternary composition), in addition to field stages for sample collection and petrographic thin-section analysis. The study area comprises two main lithostratigraphic units: the Araxá Group (approximately 80% of the area), represented by garnet-muscovite-biotite schists with restricted and subordinate amphibolite lenses, and the Monte Carmelo Complex (approximately 20% of the area), composed of granitoid bodies. Based on color, mineralogical, and textural attributes, the Boa Esperança Granite was subdivided into two facies: grayish monzogranite (grayish facies) and whitish monzogranite (whitish facies), with the additional occurrence of a banded gneiss in the area. Mineralogically, the granitic facies and the observed gneiss share a composition of quartz, K-feldspar, plagioclase, biotite, and muscovite, with garnet as a significant accessory mineral. The Boa Esperança Granite also records intense compressive tectonic deformation related to the Brasília Fold Belt, evidenced by intracrystalline plastic deformation features such as undulatory extinction and stretched quartz ribbons, mechanical deformation lamellae and twinning in plagioclase, and core-and-mantle textures in porphyroclasts, displaying a syn-tectonic character. The body exhibits a peraluminous affinity, generated by the anatexis of aluminum-saturated metasedimentary protoliths. Late- to post-magmatic deuterics (hydrolysis) were also identified, marked by widespread and intense sericitization of plagioclase crystals. These results refine the local geological framework and contribute to the understanding of the regional structural and metamorphic compartmentalization of the Internal Zone of the Brasília Belt.

2026-07-28T00:00:00Z https://repositorio.ufu.br/handle/123456789/50007 2026-09-03T06:28:25Z 2026-03-19T00:00:00Z

Title: Análise multivariada aplicada à caracterização química de rochas carbonáticas do marco Lula, pré-sal da Bacia de Santos Abstract: Since the discovery of the pre-salt reserves in the Santos Basin, significant progress has been made in understanding non-marine carbonate reservoirs, although debates persist regarding depositional processes and spatial distribution. In this context, the Lula’s Fingers stands out, located at the top of the Barra Velha Formation, near the evaporitic succession of the Ariri Formation. This interval is characterized by total and spectral gamma-ray anomalies, particularly uranium, and gathers consistent evidence of microbial activity and subaerial exposure, contrasting with the classical abiotic precipitation model. Given the relevance of the Lula’s Fingers, this study aims to identify and describe the textures, sedimentary structures, and diagnostic chemical signatures of the interval, as well as to compare results from wells drilled in the Tupi and Iracema Fields. To achieve this, a multi-technical and multi-scale analysis was proposed, involving drill cores, petrographic thin sections, and chemical analyses via portable X-ray fluorescence (p-XRF) and SEM-EDS from three wells (A, B, and C). Quantitative p­XRF chemical data were processed using an unsupervised machine learning algorithm to define chemical facies, while SEM-EDS point data were used to refine these facies and improve the understanding of compound distribution. Results show that the Lula’s Fingers is essentially composed of in situ rocks, calcilutites (CLU), spherulestones (SPH), and shrubstones (SHB), and reworked rocks, such as calcarenites (CRE) and calcirrudites (CRU), with a notable recurrence of CLU featuring irregular or crenulated laminations. The proportion and stacking patterns of these lithologies vary significantly between wells, with distinct features in Well C (Iracema Field) suggesting a different tectonic pattern compared to the Tupi High. Multivariate cluster analysis identified four common chemical facies (FQ1, FQ2, FQ3, and FQ4) across all three wells, with a localized occurrence of FQ5 in Well C. These facies record distinct diagenetic and depositional processes, including dolomitization, silicification, increased detrital input, high evaporation rates, and hydrothermal influence. Probability analysis indicates the establishment of microbial plains associated with the shallow lacustrine pre-salt system, with evidence of marine incursions. This integrated approach not only advances data processing methodologies but also provides a better understanding of the paleoenvironmental evolution of the Lula’s Fingers, reinforcing the importance of integrating petrographic and chemical data in characterizing complex depositional systems such as the pre-salt of the Santos Basin.

2026-03-19T00:00:00Z https://repositorio.ufu.br/handle/123456789/49979 2026-09-02T06:20:21Z 2026-03-18T00:00:00Z

Title: Aplicação de Rock typing na caracterização de reservatórios do pré-sal na Bacia de Santos: um estudo de caso com fácies químicas Abstract: Driven by the discovery of large oil reserves in the pre-salt interval of the Brazilian eastern margin basins, the last few decades have been marked by significant advances in the understanding of non-marine carbonate rocks. Despite this progress, understanding the heterogeneities of these rocks remains a significant challenge. Therefore, using an integrated approach, this study incorporates: (i) lithological and mineralogical data acquired at macro- and microscopic scales; (ii) geochemical data, expressed through chemical facies defined by multivariate analysis; and (iii) porosity (%) and permeability (mD) data, all obtained from core samples from two wells (A and B) drilled in the Tupi Field, pre-salt of the Santos Basin. The study aims to integrate the rock typing classification method with petrographic and geochemical data to deepen the understanding of depositional and diagenetic controls on the permeability–porosity properties of pre-salt carbonate rocks. The results indicate that, although similar, the analyzed successions present particularities regarding the relative abundance of lithologies and primary chemical composition, especially with respect to siliciclastic contribution. Although they exhibit the same dolomite textures (blocky, mosaic, lamellar, fringing, saddle, and rhombohedral) and silica textures (microcrystalline, macrocrystalline, and chalcedony), there is a clear differentiation between the wells in terms of the intensity of depositional processes. This diversity becomes evident when establishing relationships among lithologies, chemical facies, dolomite and silica textures, and Global Hydraulic Elements (GHE), which categorize the study intervals according to flow capacity. As a general trend, Well A presents a highly heterogeneous multi-petrotype system (GHE 1 to 9), with a predominance of GHE 4 and 5. In this case, the diagenetic influence did not follow a simple inversely proportional relationship; partial dolomitization and fracturing of silicified intervals contributed to the best petrophysical performance (GHE 8 and 9), identified in the intermediate portion of the Barra Velha Formation. In contrast, Well B revealed a more homogeneous reservoir with moderate performance (GHE 1 to 8, predominantly GHE 4 and 5). Its best interval (GHE 8) is also located in the intermediate portion of the well, within the Barra Velha Formation, influenced not only by diagenesis but also by greater detrital contribution. Thus, the quality of pre-salt reservoirs results from the interaction between depositional inheritance and diagenetic processes, configuring a variable and heterogeneous permeability–porosity system and making multi-technique integration indispensable for its characterization.

2026-03-18T00:00:00Z