https://ri.ufs.br/jspui/handle/riufs/2565 2026-05-01T19:24:02Z https://ri.ufs.br/jspui/handle/riufs/24898 Título: Mapeamento geológico de detalhe e controles estruturais e hidrotermais da mineralização aurífera da Mina do Paiol, Almas (TO) Autor(es): Sampaio, Nicolle Cerqueira Abstract: Gold deposits hosted in greenstone belt sequences require integrated approaches for the proper understanding of their lithological, structural, and hydrothermal controls. In the municipality of Almas, southeastern Tocantins State, the Paiol gold deposit is located at the northernmost portion of the Brasília Belt, at the base of the Riachão do Ouro Group, within a greenstone belt–related geological setting. The area is characterized by rocks metamorphosed under greenschist facies conditions and subsequently affected by hydrothermal events. In this context, this study aimed to produce a detailed lithological–structural map of the Paiol Mine, focusing on the identification and characterization of lithologies, the interpretation of the main structural controls, and the analysis of the relationship between Au grades, lithotypes, and hydrothermal alteration styles. The methodology integrated open-pit geological mapping, description of reverse circulation (RC) drill holes, geochemical analyses of RC samples and grab rock samples by fire assay with MP-AES determination, as well as data interpretation and statistical treatment of the geochemical results. The mapping allowed the individualization of five main lithotypes, derived from a mafic volcanic protolith of the Córrego do Paiol Formation, which, according to regional data and previous petrographic studies, was subjected to amphibolite facies metamorphism and subsequently retrogressed to greenschist facies conditions. In the Paiol Mine area, these lithotypes are intensely reworked by ductile transcurrent shear and hydrothermal alteration processes, macroscopically recognized by mineral assemblages involving chloritization, sericitization, carbonation, silicification, and sulfidation. Shear zones with a preferential NNE–SSW orientation were recognized, responsible for the development of penetrative mylonitic foliation and for the geometric control of mineralization. Lithology-based statistical analysis indicates that the highest average gold grades are associated with the most deformed and most intensely silicified lithotypes, highlighting the direct relationship between structural permeability, fluid–rock interaction, and metal precipitation efficiency. The first detailed geological map of the Paiol Mine enabled the representation of dextral ductile shear zones that control the deposit, influence the direction and continuity of mineralization, and define the internal architecture of the host lithologies. 2026-03-06T00:00:00Z https://ri.ufs.br/jspui/handle/riufs/23724 Título: Paleontologia e bioestratigrafia na transição Cenomaniano-Turoniano da área de Jardim, Formação Cotinguiba, em Sergipe Autor(es): Begalli, Luísa Rocha Abstract: The Sergipe-Alagoas Basin stands out for containing one of the most complete and well-exposed Cretaceous carbonate successions, associated with a rich and diverse ammonoid fauna. The main objective of this work was to carry out the identification, systematic description, and biostratigraphic interpretations of ammonoid mollusks (Class Cephalopoda) collected in the Jardim area, from the Cenomanian-Turonian interval (Upper Cretaceous) of Sergipe. Forty-six ammonoid specimens were identified and described from the Jardim 1, 2, and 5 localities, distributed into one family, four genera, and nine species: Watinoceras praecursor, Euomphaloceras costatum, Euomphaloceras sp. 1, Euomphaloceras sp. 2, Pseudaspidoceras flexuosum, P. pseudonodosoides, P. footeanum, Pseudaspidoceras sp., and Vascoceras gamai. This work records the first occurrence of Watinoceras praecursor in Sergipe. The studied fauna was assigned to two biozones: the Euomphaloceras septemseriatum Interval zone (upper Cenomanian), consisting of Euomphaloceras costatum, Euomphaloceras sp. 1, Euomphaloceras sp. 2, Pseudaspidoceras pseudonodosoides, and Vascoceras gamai, and the Vascoceras harttii Interval zone (lower Turonian), composed of Watinoceras praecursor, Pseudaspidoceras flexuosum, and P. footeanum. The biostratigraphic analysis of the ammonoid assemblages possibly indicates the Cenomanian-Turonian transition at the Jardim 1 locality. For a biostratigraphic refinement, systematic and detailed collections are suggested in stratigraphic sections that encompass the Cenomanian-Turonian transition. The analysis of the geographical distribution of the studied ammonoid species indicated mainly a Tethyan affinity. 2025-10-13T00:00:00Z https://ri.ufs.br/jspui/handle/riufs/22070 Título: Mineralogia e geoquímica dos skarns de W-Mo da mina Brejuí, Faixa de Dobramentos Seridó, Rio Grande do Norte Autor(es): Farias, Samuel Lucas Monteiro de Abstract: The Brejuí Mine is geologically situated within the Seridó Fold Belt, located in the Borborema Province - one of the main geotectonic terrains of northeastern Brazil that formed during the Brasiliano/Pan-African Orogeny (Neoproterozoic), where Ediacaran to Cambrian-aged granitic intrusions favored the development of various mineralization types, particularly the skarn-type deposits of the Seridó Scheelite Province, such as the W-Mo deposits addressed here. The objective of this work is to analyze the mineral parageneses of the skarns at Brejuí Mine and their associated hydrothermal alteration processes. These skarns, locally called "tactites", are calc-silicate rocks hosted at the contact between lithotypes of the Seridó Group, specifically between marbles and paragneisses of the Jucurutu Formation, where hydrothermal fluids rich in volatiles and metals promoted the formation of these calcic skarns and subsequent scheelite deposition. The W-Mo mineralizations are associated with multiple stages of metasomatic/hydrothermal alteration, as evidenced by studies conducted in this work involving the integration of optical microscopy, electron microscopy (SEM/EDS) and Xray fluorescence (XRF) data, where three main stages of hydrothermal alteration were identified, compatible with the regional metallogenic evolution: (1) an intermediate stage between the metasomatic and hydrothermal phases, marked by the replacement of grossular and diopside by epidote and vesuvianite, indicating Ca-W-Si-rich fluids; (2) a secondary hydrothermal stage with predominance of epidote, calcite and vesuvianite; and (3) an advanced hydrothermal stage characterized by the deposition of scheelite, sulfides (chalcopyrite, molybdenite) and magnetite, confirming S- and metal-enriched fluids. Furthermore, late-stage parageneses (zeolites, sulfides) suggest variable redox conditions during hydrothermal evolution, which remain poorly explored in the literature. This work reinforces the importance of integrating analytical techniques for understanding mineralized systems in complex environments like Seridó, and highlights the need for future studies in isotopic geochemistry and fluid microthermometry to completely elucidate the deposit's genesis. 2025-04-30T00:00:00Z https://ri.ufs.br/jspui/handle/riufs/21573 Título: Arcabouço estratigráfico de alta resolução do Campo de Rabo Branco, Bacia de Sergipe-Alagoas : uma abordagem sismoestratigráfica Autor(es): Oliveira, Luana Áfele Santos de Abstract: Revitalization campaigns for mature onshore fields in Brazil have made the Rabo Branco Field an important focus of study. Located in the onshore portion of the Sergipe SubBasin, southeast of the Carmópolis Field in the Sergipe-Alagoas Basin, the field presents significant potential for new analyses aimed at increasing its recovery factor. This study aims to conduct a high-resolution stratigraphic interpretation of the field based on five wells, integrated with a seismic-stratigraphic approach emphasizing the Muribeca, Riachuelo and Cotinguiba Formations. Four seismic facies were defined, representing distinct depositional environments: undulated and segmented seismic facies, respectively associated with a fluvial environment and deposition surfaces linked to faults, both related to the Muribeca Formation; subparallel seismic facies, indicating platform environments, associated with the Riachuelo and Cotinguiba Formations; and chaotic seismic facies, related to gravitational flow deposits of the Calumbi Formation. We defined low, medium, and high frequency sequences based on the detailed analysis of the composite well logs, allowing the identification of three higher-order systems tracts based on T-R cycles. The results indicate that wells 4-GALP-36-SE, 1-GALP-12- SE, and 1-CAB-02-SE are positioned in a depocenter region, considered more distal, while wells 1- GALP-11-SE and 1-VF-01-SE are located in a more proximal area. It was observed that the Regressive Systems Tract 1 mainly coincides with the reservoir intervals of the field, corroborating previous interpretations not published in the literature, that indicate the petroleum system is mainly associated with the Carmópolis, Ibura, and Oiteirinhos members of the Muribeca Formation, being the source rock from the rift stage. 2025-03-10T00:00:00Z