Abstract Since its definition over 120 years ago, several key sedimentological and stratigraphic questions have emerged regarding the Estrada Nova succession (Serra Alta and Teresina/Corumbataí formations) of the Paraná Basin. These units developed during the disconnection of basin waters from Panthalassa and the progressive continentalization of southwestern Gondwana during the Permian, marking a distinctive stage in basin evolution. To clarify this interval, we integrated stratigraphic, sedimentological, paleontological, and geochronological data with detailed facies analysis across 28 measured sections in Mato Grosso, Goiás, São Paulo, and Paraná states. This regional survey refined stratigraphic correlation among late Permian units and revealed basin-scale filling patterns not previously recognized. Fischer diagram analysis allowed construction of accommodation curves showing striking similarities across successions in the northwestern, central, and southern basin. The recognition of a consistent stratigraphic architecture suggests depositional responses to climatic fluctuations, subsidence, and base-level changes were more homogeneous and synchronous than assumed. From a lithostratigraphic perspective, our revised framework simplifies debated stratigraphy by reaffirming the Serra Alta Formation throughout the basin, confirming correlation between Corumbataí and Teresina, and proposing that the upper Corumbataí and lower Rio do Rasto Formation may have been deposited contemporaneously, separated by local topographic highs.
Abstract Rosário-16 (R-16) is a hypabyssal transitional kimberlite, divided into two volcanic pipes, R-16-A and R-16-B, within the Kimberlite Province of Rosário do Sul (KPRS), southeast of the Paraná Basin (PB), southeast Brazil. The saprolite outcrops, within a NE/SW structure, occur next to the Rosário-6 alnöite, comprising microcrysts of olivine, Mg-chromite, Mg-ilmenite, diopside, phlogopite, fluorapatite, and perovskite. R-16 also contains microxenocrysts, potentially derived from peridotitic macrocrysts, characterized by electron microprobe analyses. Calculation of pressure, representative temperature (based on averaged mineral compositions), and oxygen-fugacity conditions using geothermobarometers for olivine and spinel, and an oxygen barometer for perovskite, indicates pressures of ≥ 4 GPa, a representative temperature of ~1135 °C, and ƒO2 (oxygen fugacity) values between ΔNNO = –3.92 and –1.35. Chemical analyses indicate that CO2 metasomatism in R-16 was less than Rosário-6 alnöite. We found that CO2 reactions occurred in the mantle at higher pressures in R-16, resulting in the generation of kimberlitic magma through silicate interaction with carbonatitic liquids. The similarity between the ƒO2 versus temperature profiles of R-16 and high/low-Ti PB tholeiites suggest a heterogeneously metasomatized mantle source for the KPRS with the emplacement of R-16 favored by the Gondwana breakup.
Abstract The Ribeira Belt in southern Brazil records the Neoproterozoic tectonic evolution associated with the amalgamation of Western Gondwana, and its shear zones provide critical constraints on transcurrent–transpressive deformation regimes. Within this framework, the Atuba Complex in the Curitiba Terrane hosts the São Jorge quarry, where metatexites preserve evidence of progressive deformation. This study investigates feldspar intracrystalline plasticity and quartz–feldspar microstructures to better understand deformation mechanisms and their significance for strain partitioning during the evolution of the Curitiba Shear Zone. Petrography, structural analysis, finite strain quantification (Fry, Polar, Rf/ϕ), and electron backscatter diffraction (EBSD) were combined to characterize deformation fabrics. This research analyzes feldspar crystals to investigate intracrystalline plasticity, while finite strain quantification was primarily based on quartz grains, which serve as reliable markers for bulk strain estimates. Three deformation stages were identified: (i) ductile shear producing mylonitic metatexites with steep NE–SW foliation and sinistral kinematics, (ii) overprinting brittle–ductile deformation, and (iii) late brittle fracturing. Quartz microstructures, including lobate boundaries and grain boundary migration, indicate deformation temperatures exceeding 500°C, while feldspar exhibits undulatory extinction, subgrain formation, and moderate dynamic recrystallization. EBSD data reveal a crystallographic preferred orientation of albite consistent with {100}<010> slip, also suggesting deformation at ~500°C. Finite strain ratios are low (R ≈ 1.5-2.1), reflecting the last local increment of deformation rather than the total bulk strain, and indicating limited strain accumulation despite localized intense shearing. Brittle–ductile overprints are marked by fractures, fault zones, grain-size reduction, and comminution. Taken together, we interpret the deformation at the São Jorge quarry to be progressive, transitioning from ductile to brittle regimes within a transcurrent–transpressive setting. This interpretation provides new constraints on the structural evolution of the Atuba Complex and Curitiba Terrane and contributes to broader models of strain accommodation in the southern Ribeira Belt during the Brasiliano Orogeny.
Abstract The Novo Mundo granitic Complex lies in the southernmost margin of the Amazonian Craton, Brazil. New petrological, geochemical, U–Pb and Sm–Nd isotopic data allow us to propose a new petrogenetic model for granite genesis in the southernmost portion of the Craton. Earlier studies attribute the complex to the Tapajós–Parima Tectonic Province. Four granitic facies have been identified: quartz monzonite, monzogranite, biotite granodiorite, and syenogranite, all of which are crosscut by diabase dikes. The monzogranite has primary muscovite. The biotite from the granites shares chemical signatures with that of volcanic arc settings. Petrographic data, mineral chemical, lithogeochemical, and isotopic data allow conclude that the Novo Mundo rocks into I-type, meta– to peraluminous, and calc–alkaline to alkali-calcic granites which are compatible with volcanic arc settings and varying degrees of crustal contribution. U–Pb LA–ICP–MS ages of magmatic zircons (quartz monzonite 2032 ± 6 Ma; monzogranite 2029 ± 4 Ma; biotite granodiorite 1989 ± 6.2 Ma; syenogranite 1987 ± 7.4 Ma) and TDM Nd model ages (2.52-2.15 Ga; ɛNd(t) = -2.0 to +1.81) indicate that the granites originated from either mantle-derived or juvenile Orosirian crustal melts, with additional continental crust input. The weak positive ɛNd(t) anomalies suggest an upwelling asthenospheric mantle that provided the thermal input to remelt the lower crust, as well as the isotopic data emphasize varying levels of crustal reworking during arc evolution. These ages are coeval with the evolution of the Paleoproterozoic Cuiú-Cuiú Magmatic Arc emplaced during the main stage of arc subduction in the region (2.05-1.99 Ga). The proposed evolutionary model suggests that quartz monzonite and monzogranite are associated with the early stages of arc evolution. The granodiorite records the contribution of juvenile sources, correlated with episodes of mafic magma influx, while the syenogranite represents the final stages of the arc formation, indicating a predominance of continental crustal contribution. The new data, combined with recent studies, allow us to suggest the existence of a Paleoproterozoic continuous magmatic arc into the south part of the Amazonian craton instead of the previously defined tectonic provinces previously defined in the literature.
Abstract Studies integrating ichnology and sedimentology in paleoenvironmental interpretations are rare in Brazilian rift successions. This study applies an integrated ichno-sedimentological analysis to a well core from the Resende and Tremembé Formations (Cenozoic Taubaté Basin) to reconstruct paleoenvironmental conditions. Three paleoenvironments were identified: alluvial fan, braided river, and lacustrine. The alluvial settings is characterized by coarse-grained deposits displaying bioturbation intensity and sporadic trace fossils, dominated by Palaeophycus and Skolithos, reflecting opportunistic colonization. Braided river deposits consist of stacked sandstones with trough cross-bedding and a trace-fossil assemblage with Palaeophycus, Skolithos, Macanopsis, and Taenidium. The lacustrine environment is characterized by dark shale interbedded with fine-grained sandstones, including ostracod-rich white beds. Sparse beds containing Planolites indicate a complex lacustrine system with potential variations in salinity and oxygenation. Comparison with previous studies suggests that ichnofossils and paleosols reflect water table fluctuations and humid conditions in the Resende Formation. For the Tremembé Formation, ichnofossil data, palynomorphs (Botryococcus and Pediastrum), and taphonomic signatures in fishes suggest a dynamic environment with fluctuating water levels, periodic salinity increases, and decreased oxygen levels.
Abstract The Sana (Sana suite) and Itaoca (Nova Friburgo suite) granites, emplaced in the Oriental Terrane of the Ribeira Belt during the Cambrian–Ordovician, provide key insights into post-collisional magmatism in a Gondwana segment marked by crustal recycling. We present new Sm–Nd and Rb–Sr isotope data for 26 samples from both plutons, combined with petrographic information, to evaluate magma sources and the applicability of I- and S-type classification. The Sana Granite is strongly peraluminous and dominantly S-type, derived mainly from metasedimentary sources of the São Fidélis Group with minor arc-derived input, supported by isotopic evidence and rare titanite (< 1%). In contrast, the Itaoca Granite is metaluminous, titanite-rich, and consistent with I-type, reflecting melting of mafic to high-K orthogneisses of the Rio Negro Magmatic Arc. Mixing models suggest ternary contributions from arc and sedimentary reservoirs but remain exploratory due to limited Sr data for sources. Both plutons share overlapping Nd and Sr isotope fields, with initial 87Sr/86Sr ratios of 0.7008–0.7078 and consistently negative εNd(t) (–11 to –13), highlighting isotopic convergence in the Oriental Terrane. These results show that, despite contrasting S- and I-type traits, both granites reflect hybridization and a shared tectonic framework, emphasizing the limitations of strict isotopic classification and the need for integrated petrographic approaches.
Abstract Paleohelcura tridactyla is a trackway characterized by up to three round tracks per series, typically arranged linearly or triangularly, often with a medial impression. This pattern is consistently found in several eolian deposits and has been described in the Botucatu Formation in Brazil, an eolian sandstone unit in the Paraná Basin deposited during the earliest Early Cretaceous under arid conditions. Here, we describe a new small morphotype of Paleohelcura tridactyla in the Botucatu Formation. This morphotype is smaller than previously described specimens of Paleohelcura tridactyla, and although it shares a similar size with Paleohelcura araraquarensis, it differs both in track morphology and series arrangement. We propose three hypotheses for the new morphotype: (1) The trackway may have been produced by the juvenile stage of the arthropod responsible for the larger Paleohelcura tridactyla tracks. (2) The size difference may indicate sexual dimorphism within the same species. (3) Alternatively, it could represent a different arthropod species, which is smaller in size but leaves similar track patterns. This discovery reinforces the ichnotaxonomical distinction between P. tridactyla and P. araraquarensis and raises the possibility that another arthropod species may have been present in the Botucatu Paleodesert fauna.
Abstract Lateritic formations are widespread in eastern Amazon, occurring as bauxite-bearing mature profiles on plateaus or as immature ones in lowlands. Climate and landscape evolution over the Neogene were analyzed via mineralogical (XRD), textural (optical microscopy), and geochemical (ICP-OES, ICP-MS) methods carried out in a selected lateritic profile outcropping in Abel Figueiredo. The profile features columnar and nodular iron crust, overlaid by a spherulitic horizon formed of hard fragments in clayey matrices, covered by yellow topsoil. Major minerals include hematite, goethite, kaolinite, and quartz, with minor anatase and heavy minerals. Hematite and goethite dominate lower horizons, while kaolinite, quartz, Al-goethite, and anatase appear in the matrix and topsoil. Trace elements were immobilized by iron oxyhydroxides and anatase or maintained in zircon and other resistate minerals. Mineralogy and geochemical distribution indicates a transition from iron crusts to fragmented iron crust, followed by physical reworking, leading to the formation of nodules and spherulites, with clay accumulation in between. In a final stage, a topsoil developed over the profile. This set of events requires an alternation between humid tropical climate with more arid conditions, with implications to rainforest and savanna development, resulting in mineral formation and chemical or physical decomposition.
Abstract The Proterozoic pre-collisional basins of the Araçuaí orogen consist of a succession of superimposed basins that overlie the eastern margin of the São Francisco Craton. This report proposes new stratigraphic and tectonic models for the evolution of the pre-collisional basins of the Araçuaí orogen. They are younger than the Rhyacian orogeny and predate the Ediacaran orogeny. The Orosirian Costa Sena sineclisis was a submerged, N-S asymmetric basin. The onset of the Statherian Espinhaço rift system followed, consisting of four asymmetric rifts, bounded by N-S, west dipping normal faults. The faults are connected at depth to a detachment, exposed at the eastern border of the southern Espinhaço range. The taphrogenic process was caused by an asthenospheric heat flow, from underneath the São Francisco proto-Craton, moving eastward, below the Gouveia complex. After a geological hiatus greater than 400 Ma, the basin activity resumed when the temperature below the Gouveia complex was high enough to create a thermal heat flow, directed toward the east, below the Guanhães complex. Asthenospheric heat flow acting below a younger detachment zone governed the development of the remaining Stenian Tonian Cryogenian pre-collisional basins, continental breakup and oceanic crust generation.
The analysis of sediment accumulation rates from cores collected from marine environments has enabled the reconstruction of depositional records spanning the past century using radionuclides such as Pb-210. Pb-210 is a member of the U-238 decay series and is commonly used to investigate recent processes owing to its half-life of 22.3 years. This radionuclide enters the marine environment through dry and wet conditions and from the decay of its parent isotopes. Pb-210 is particularly effective in determining the accumulation rates within the sediment layers formed from 5 to 100 years. This study focused on the Corea & uacute; River Estuary, located in Camocim on the Cear & aacute; coast of Brazil. Nine sediment cores collected throughout the estuary revealed steady-state sediment accumulation rates in some of the cores. In the other cores, the Pb-210 profiles were slightly inconclusive. These cores exhibited substantial bioturbated mud in the upper 10-30 cm, below which the radioactivity decreased abruptly. These findings provide insights into sediment accumulation across the estuary, particularly near its mouth. Our findings indicate sediment accumulation was more rapid on the eastern bank and near the estuary mouth and was likely influenced by estuarine hydrodynamics and the influx of organic material from human activities into the secondary channels of the river. These findings highlight the importance of monitoring sediment dynamics in estuarine systems impacted by human activities and provide a foundation for future coastal management and conservation efforts. Further research incorporating additional dating methods and hydrodynamic modeling is recommended to refine sedimentation trends and their long-term implications.
Although many paleogeographic reconstructions depict equatorial Brazil as being predominantly arid during the Aptian, studies using palynomorphs suggest climatic fluctuations between humid and arid phases. There is, however, a lack of studies utilizing additional proxies to demonstrate such changes. We present a case study for climatic variation in an Aptian continental to transitional system in the Araripe Basin, Brazil, applying geochemical, palynological and ostracod analyses, integrated with previously published sedimentologic and stratigraphic data from the Barbalha Formation (46 samples; drill core 1PS-06-CE). Cluster analysis of micropaleontological and weathering proxies allowed to identify seven climatic clusters (G1-G7): G1-G4 from the Batateira Beds (lower Barbalha Formation) and G5-G7 from the upper Barbalha Formation. G1-G4, linked to lacustrine facies, indicate a generally more humid interval, with proxies showing intense weathering and longdistance element transport. Paleoredox data suggests low oxygenation. In contrast, G5-G7, associated with bayhead delta environments, reflect a relative increase in aridity, with reduced weathering and evidence of subaerial exposure of organic particles. Nevertheless, humidity persisted, supported by the occurrence of pseudo amorphous organic matter and marine ichnofossils. These results show that despite an overall arid trend, significant moments of humidity were still present in equatorial Brazil during the Aptian.
Abstract The Miguel Amaral Burgueño Paleontological Site is an important fossiliferous Quaternary deposit located in the middle course of the Apa River, municipality of Bela Vista, State of Mato Grosso do Sul. In this study we analyzed nineteen fossils of the Quaternary megafauna discovered in longitudinal gravel bars in fluvial deposits. The taxa are represented by Eremotherium laurillardi and Notiomastodon platensis associated with pebbles and gravel after reworking and tractive efforts by the fluvial transport. The fossils are fragmented and disarticulated with a low degree of weathering and with E-W imbrication. Taphonomic and sedimentary features indicate that the fossils were reworked from sedimentary deposits adjacent to the channel of the Apa River near the deposition site.
Abstract Silicification is a diagenetic process that affects the porosity and permeability of carbonate rocks, such as those in the Itapema and Barra Velha formations, Pre-salt of Santos Basin. This contribution integrates macroscopic and microscopic descriptions of silicified intervals, identifying controls and mechanisms of dissolution, replacement, and precipitation, relating them within the diagenetic history of the formations. The pre-compaction eodiagenetic silicification comprises tabular and nodular geometries, reflecting fine-grained laminated and coarser-grained massive lithologies. The post-compaction mesodiagenetic silicification comprises irregular silica disseminated throughout carbonates. Silica bodies consist of replacive (cryptocrystalline silica, mosaic microcrystalline quartz and spherulitic chalcedony) and pore-filling textures (chalcedony and macrocrystalline quartz). The highly selective nature of the replacement suggests that carbonate dissolution initiates silica precipitation as a fluid-mediated process that transfers crystallographic information. The successive zoning with decreasing crystallinity in filling/cement textures indicates a decrease in the fluid supersaturation as the precipitation advances. These features indicate that textures and silicification mechanisms reflect precipitation physicochemical conditions. The first silica event follows the dolomitization stage that replaces primary clays and carbonates, while the second event occurs after mechanical compaction and is later followed by replacive/pore-filling barite textures. Late macrocrystalline quartz veins host primary hydrocarbon fluid inclusions, linking the second silicification event with oil migration.
Abstract The presence of deformation bands (DBs) associated with porous volcaniclastic rocks, it is ubiquitous but poorly described. In Trindade Island, the Paredão Volcano's lapilli tuffs are deposited during the Middle Pleistocene, and several deformation bands are associated with conjugate pairs geometry. To analyze the structural geometry and mineral phase of host rocks, we employed a multiscale approach that included regional fracture and geometry studies in the field, microtectonics with a support of scanning electron microscopy (SEM-EDS), and 2D petrophysical properties analysis. The analysis revealed that the deformation bands result from two mechanisms. The first is a granular flow mechanism characterized by grain rotation and matrix reorganization. This mechanism is also associated with fluid flow and matrix zeolitization. The second mechanism is a cataclastic flow marked by crystal fragmentation and the formation of a fine-grained matrix. It is observed that the pre-existence of mineral cleavages and fractures facilitates these mechanisms. The combination of these two mechanisms, driven by fluid flow, leads to the development of cataclastic bands characterized by the loss of porosity, matrix reorganization, and distinct geometric patterns. Those mechanisms are suggested to be developed in a transtensional context related to the Vitória-Trindade Fracture Zone.
Abstract Two tholeiitic magmatic events are recorded at the Eastern Border of the Parnaíba Basin comprising the Jurassic Mosquito Formation and the Cretaceous Sardinha Formation. They are chronocorrelated to the Central Atlantic Magmatic Province Large Igneous Province (CAMP LIP) and Equatorial Atlantic Magmatic Province (EQUAMP LIP), respectively. The latter is also chronocorrelated with the Paraná-Etendeka Province (PEMP LIP). Five groups of tholeiitic rocks are representative of magmatic episodes with different ages and tectono-magmatic context: Low-Ti Group I, High-Ti Group IIa, High-Ti Group IIb, High-Ti Group III, and High-Ti Group IV. The geochemical data of Groups I, IIa, and IIb are similar to those of tholeiitic basalts from Jurassic CAMP LIP, whereas rocks in Groups III and IV can be related to the Cretaceous EQUAMP LIP as well as High-Ti basalts of the PEMP LIP. The chemical differences between the two magmatic events indicate changes in the mantle composition underlying to the Parnaíba Basin over geological time. It is likely that the Brasiliano-Pan African orogenies, which preceded Jurassic rifting, affected the mantle sources of the Groups I and II magmas. Conversely, the composition of the mantle underlying the Parnaíba Basin was modified by the impingement of a mantle plume during the Cretaceous.
Abstract The AN-34 and QT-02 iron oxide–copper–gold (IOCG) prospects are located in the northern portion of Carajás Mineral Province (CMP), where important copper IOCG deposits occur. This region lacks basic geological information on the outskirts of the large IOCG deposits, and these small prospects might provide information regarding fluid–rock interaction and alteration-mineralization styles. In these prospects, banded iron formations (BIFs), basic volcanic rocks, and granitoids are variably deformed and hydrothermally altered. The hydrothermal alteration evolved from early silicification, potassic alteration, and Fe enrichment. All these alterations are pervasive and linked to shearing structure development. They are followed by late, ductile-brittle, chloritic alteration and sodic alteration. The quartz–magnetite oxygen isotope geothermometry (δ18Oqtz–mag) and chlorite geothermometry reveal a decrease in the temperature of the hydrothermal system from 520°C ± 30°C to 273°C ± 20°C. The calculated δ18OH2O for silicification (6.6–5.8‰) and Fe enrichment (9.2–10.47‰) suggest the involvement of magmatic fluids. δ18OH2O values from 0.27 to 0.77‰ and 1.7 to 3.3‰ from late sodic alteration and hematite are compatible with meteoric fluids. Our findings shed more light on the fluid–rock interaction, hydrothermal evolution, and mineralization styles in the IOCG deposits of the northern sector of the CMP.
Poorlylithified siliciclastic rocks correspond to important post-salt reservoirs in the Southeastern Brazilian Margin offshore basins. These reservoirs present challenges regarding the prediction of the hydraulic behavior of faults due to low cohesion leading to diffuse brittle deformation. To improve the understanding of the deformation influence on the reservoir quality of these rocks, this paper presents a 3D modeling method based on an outcrop analog composed of Paleogene poorly lithified fluvial siliciclastic deposits in the Volta Redonda Basin (Continental Rift of Southeastern Brazil). A database was collected containing a 3D digital terrain model of the outcrop, a 1:50-scale geological section, permeability and porosity measurements, and lithological and sonic log from a well drilled upon the outcrop to the basement. Two models were built: one using traditional methods for industry where properties were uniformly distributed throughout the grid and a second model where sectors were delimited and populated with data from deformed rocks, highlighting the impact of tectonic structures (faults and deformation bands) on fluid flow, reducing the permeability by one order of magnitude, and increasing the flow time between wells by more than 10%. This study contributes to improving reservoir modeling accuracy, enhancing the understanding of fluid flow behavior in complex, deformed, poorly lithified rocks.
Abstract The Upper Jurassic to Lower Cretaceous Botucatu Formation of the Paraná Basin consists primarily of trough cross-bedded eolian sandstone deposited in an intracontinental desert. In southeastern Brazil, an unusual occurrence of conglomerate and coarse-grained sandstone unconformably overlies the Neoproterozoic basement and is overlapped by volcanic rocks of the Serra Geral Formation. This represents one of the few documented occurrences of fluvial facies described for the Botucatu Formation in the northern part of the basin. To determine its depositional system and source area, we conducted facies and paleocurrent analysis, detrital grain modal counting, macroscopic provenance, and conventional heavy mineral analysis. The integrated analysis suggests that the studied succession was deposited by an ephemeral fluvial system at the margins of the extensive dune fields of the Botucatu paleodesert. Paleocurrent data and detrital composition indicate sediment dispersal toward the SE, with a possible source area associated with a recycled orogen to the NW (Brasília Belt). Although ephemeral rivers acted as important sediment suppliers for this continental-scale desert, recycling of eolian sediments by fluvial systems is not ruled out. Finally, using a multi-proxy approach, we present a paleogeographic scenario for the northern margin of the Botucatu paleodesert during the last period of Gondwana, prior to its initial rifting.
Abstract The structure of two superposed layers within a redox-altered basaltic flow is restricted to the Paraná Volcanic Province among large igneous provinces. World-class amethyst-geode and agate-geode deposits occur in reduced Tier 1 of the Cordillera Flow (> 100 km long). Satellite and drone-sourced imagery, several field surveys, and 11 new geochemical analyses were used in this study. The lower Tier 1 (10 m thick) consists of massive rocks without cooling joints, whereas the barren Tier 2 is massive with colonnade. The flow is identified from the stratigraphy and chemical composition (e.g., 1.3 wt.% TiO2). The presence of poikilitic microphenocrysts of magnetite (mostly plagioclase inclusions) is a distinctive feature. Tier 2 rocks are chemically similar to the original lava; Tier 1 displays a decrease in SiO2 and K2O contents and an increase in Fe2O3T. Reducing and acidic hot water formed amethyst and agate deposits in Tier 1. Curved shapes (erosional remnants with agate) were formed by silicification of the lower portion of the flow. The interaction of the Guarani Paleoaquifer with the lava flow formed the two layers: the geodes and the curved portions. Other provinces may have similar features where hot aquifer water was available below the basalt.
Abstract Situated between the Campos and Santos basins, the Cabo Frio High emerges as a focal point of heightened magmatic activity during the Santonian–Campanian and the Eocene period following the breakup of these basins. The geodynamic framework associated with these events took place during their passive margin stage, wherein magmatic occurrences could potentially be attributed to the reactivation of significant geological structures or thermal enhancement facilitated by proximal hotspots, within a context of lithospheric thinning (i.e., Trindade Plume). This investigation unveils novel Sr–Nd–Pb–Hf isotope data derived from alkaline magmatic rocks extracted from three boreholes strategically positioned within the Cabo Frio High area. The evolutionary trajectory of these rocks reflects the intricate processes of assimilation and fractional crystallization. The results of the analysis and binary mixing modeling point out to an involvement of both depleted (characterized by Depleted Mantle [DM]/Mid-Ocean Ridge Basalt [MORB] or HIMU compositions) and enriched (manifesting as the Enriched Mantle I [EMI] and the Enriched Mantle II [EMII]) sources in the genesis of these magmas. Moreover, the discerned incorporation of a fertile Ocean Island Basalt (OIB-like) reservoir hints at a plausible association with the Trindade Plume, amplifying the complexity of the magmatic genesis within the studied region.
