Journal of the Geological Survey of Brazil

Phosphate mineralization of Sapucaia (Pará, Brazil) and its genetic relationship with peraluminous pegmatites of the Gurupi Belt

Yasmin Souza — 2026-03-10

Brazil is one of the world's largest food producers, but it remains dependent on the import of phosphate fertilizers. In this context, national phosphate deposits gain strategic importance, such as the Sapucaia Mine (Pará, Brazil), which hosts the first aluminous phosphate deposit in Brazil and the second in the world. Through lithological, petrographic, geochemical, and gamma spectrometric analyses, the Sapucaia Mine represents an important case study for understanding the genesis and evolution of phosphate mineralization. The profile was divided into three units from base to top: (1) a clay unit, with an aluminosilicate-rich facies dominated by kaolinite and zoned phosphates such as crandallite group minerals; (2) a phosphate-rich unit, characterized by a mineralogical association of amblygonite, wavellite, woodhouseite-svanbergite, and crandallite-goyazite series; and (3) an iron-phosphate crust, rich in iron oxides, ankerite, dufrenite, triphylite, and wavellite fillings. Strongly peraluminous signatures (A/CNK > 2), enrichment in rare earth elements (REEs), Sr, and Ba, as well as a negative Eu anomaly in REE patterns, are inferred as compatible with S-type magmatic sources. Botryoidal and colloform textures, pseudomorphic substitutions, and altered mineral features indicate a polygenetic regolithic system. The correlation between petrographic and geochemical data suggests at least three genetic processes: (i) a lithium-bearing igneous phase, associated with the intrusion of a granitic-pegmatitic body; (ii) a late-magmatic/hydrothermal phase, with significant mobilization of alkaline-earth metals; and (iii) a supergene phase, characterized by intense weathering in a tropical climate, with dissolution and reprecipitation of phosphates and clay minerals. The Sapucaia Mine constitutes a unique geological example of phosphate enrichment in peraluminous granitic terrains exposed to tropical weathering conditions, with potential applications for the exploration of analogous deposits in northern and northeastern Brazil.

The Jurassic basaltic magmatism of the Tacutu rift-type basin, Amazonian Craton, Brazil: A contribution to petrological studies

Steffanie Oliveira — 2026-05-25

The Tacutu rift-type basin (on the border of Brazil and Guyana) is related to the initial opening of the Equatorial Atlantic Ocean during the Mesozoic. On the Brazilian side, during the pre-rift stage, basaltic magmatism (Apoteri Formation) associated with a fluvial-deltaic system took place within a magma-poor rift domain. At least two basaltic magmatic pulses have been recorded (Ap1 and Ap2). These rocks are basalt to basalt-andesite in composition, with subalkaline, tholeiitic to calc-alkaline, low-Ti CAMP (Central Atlantic Magmatic Province), and intra-plate geochemical signatures. However, Ap1 displays an aphanitic to fine-grained porphyritic texture, while Ap2 has a notable vesicular textural feature. Ap1 has low MgO, high Ti, Zr, and REE, while Ap2 has high Mg, low Ti, Zr, and REE. Geochemical and isotopic (low Nd and high Sr isotope ratios) indicators point to different rates of differentiation and crustal contamination between Ap1 and Ap2, probably related to crustal residence time. The variations in depth/depocenters, interior block architecture (horst-graben), and fault movement rates controlled the volume and emplacement moment of the basaltic magmatic pulses during the Tacutu rifting. On the Brazilian side, the Apoteri basaltic volcanism had sub-aerial characteristics, with some degree of explosivity and fragmentation during the Ap2 pulse, while on the Guyana side mainly underwater volcanism took place, associated with a deltaic-marine system.

Mapping and Geodiversity characterization in Linhares, Jaguaré and Sooretama (Espírito Santo, Brazil) and implications for regional development

Fernanda Torres — 2026-04-10

This study, conducted in the municipalities of Linhares, Jaguaré, and Sooretama, in the state of Espírito Santo, southeastern Brazil, characterizes the regional geodiversity, providing essential information on the physical environment that can be used by public and private stakeholders in territorial planning, with a view to socioeconomic development (job and income generation) and sustainability (environmental protection and public health). Such information encompasses the potential of water resources (surface and groundwater), groundwater quality, and the geotechnical characterization of areas susceptible to geological and geotechnical events, which are crucial for appropriate land use and occupation.

To this end, the Geodiversity Map was produced at a scale of 1:100,000 by the Geological Survey of Brazil (SGB/CPRM), based on bibliographic research, field surveys, and analysis of physical aspects, including geology, geomorphology, soils, land use, and water quality. The mapping resulted in three geological-environmental domains, subdivided into seven units defined according to lithology and depositional environments. The unconsolidated sediment domain stands out, as it accounts for more than 88% of the mapped area. Predominantly represented by sediments of varied composition belonging to the Barreiras Formation, this domain is widely used for urban occupation and mineral exploitation, such as borrow material for civil construction and onshore petroleum production. This study provides an overview of the geodiversity of this region of the state of Espírito Santo, offering public and private managers and administrators baseline information to support the development of public policies aimed at land use, occupation, and the sustainable management of the physical environment.

Artificial Intelligence and Digital Technologies in Brazilian Earth Sciences: A Scientometric Analysis of Journal Publications (2016–2025)

Mallikarjun Kappi — 2026-06-17

This study presents a comprehensive scientometric analysis of artificial intelligence (AI) and digital technologies research in Brazilian Earth sciences, examining 1,523 Scopus-indexed journal publications from 2016 to 2025. Data were retrieved using structured keyword combinations covering machine learning, deep learning, big data, knowledge graphs, and digital transformation, restricted to Earth sciences subject areas and Brazilian institutional affiliations. The analytical framework integrates temporal, collaborative, thematic, and citation-based dimensions. The output demonstrates exceptional growth, with publication output increasing from 23 papers in 2016 to 320 in 2025, representing a compound annual growth rate of 33.90% that closely matches global AI research growth (35.00%). All these publications received a total of 30,878 citations, with an average of 20.27 citations per paper. However, citation impact declined relative to global benchmarks, with the Relative Citation Index deteriorating from 3.96 in 2016 to 0.07 in 2025, revealing a productivity influence gap. Among 6,948 contributing authors, Marcato Junior, J. (Universidade Federal de Mato Grosso do Sul) leads productivity with 32 publications and 1,885 citations, while Osco, L.P. (Universidade do Oeste Paulista) achieves the highest impact with 107.06 citations per paper from 18 publications generating 1,927 total citations. Institutionally, Universidade de São Paulo dominates with 252 publications and 6,478 citations (citations per paper: 25.71), though Universidade Federal de Mato Grosso do Sul demonstrates superior citation efficiency (citations per paper: 47.21 from 67 publications). International co-authorship characterizes 45.70% of publications. Funded research (78.73%) achieves substantially higher citation impact (21.68 versus 15.08 citations per paper). Citation concentration is pronounced: 66 highly cited papers (4.33%) account for 38.34% of total citations, dominated by remote sensing applications in elite international journals. Keyword co-occurrence analysis identified six thematic clusters (1,603 links; total link strength: 10,031), with machine learning and deep neural networks as dominant bridging nodes. Geographic and institutional concentration persists, with southeastern Brazilian institutions commanding disproportionate research output. Sustained competitiveness requires enhanced international collaboration, strategic publication venue selection, methodological diversification, and regional capacity building. Beyond scientometric mapping, these findings offer actionable intelligence for geoscientific communities and science policy, clarifying where AI methodologies have most transformed Earth sciences practice in Brazil and identifying priority domains for targeted investment in computational geoscience capacity.

Morphological changes of the Santos Estuary (Brazil) from 1876 to 2014

Julia Reid — 2026-06-18

The ability to understand the morphology of estuaries associated with temporal evolution is essential for coastal management, channel navigability, and the environment. In this study, we analyze the morphological evolution of the Santos Estuarine System (SES), based on bathymetric data between 1876 and 2014. During this period, the SES underwent morphological changes, particularly in the bathymetry of the main channel. The volume variation of the estuary suggests that the volume of the Channel of Santos (CS) had an increase in the channel capacity of around 28% over a century. Such morphological changes in the channel can alter estuarine processes and overall functioning. Therefore, monitoring the temporal changes in estuaries and their impacts is essential for predicting future scenarios related to sea level rise and climate change. Changes in channel morphology affect estuarine processes and functionality, and understanding these dynamics can improve estuarine management and navigation strategies.

Geotechnical and geomorphological blueprints of the gullied Ogwashi-Asaba Formation: examples of the Obomkpa and Nkwu-Nzu gullies, Southern Nigeria

Enivwenaye Oghenero Avwenagha — 2026-06-25

Rapid land degradation caused by gullies has impacted roads, buildings, farms, and electricity development in Obomkpa and Nkwu-Nzu areas of the Niger Delta in southern Nigeria. As a result, a study was carried out to examine the soil behavior and erosion dynamics of the gullied terrains from both geotechnical and geomorphological viewpoints. Eighteen soil samples and the morphology of the two gully sites were analysed through walk-over surveys, geotechnical testing (including gradation analysis, consistency tests, triaxial, and shear box tests), and gully morphological assessments. Gradation and consistency tests revealed that the gullies are mainly composed of silty sands that exhibit cohesionless behavior in Obomkpa and cohesive properties in Nkwu-Nzu. Geomorphological studies identified the gullies as permanent, large gullies located on high-relief zones with steep slopes, featuring unstable U-shaped and stable V-shaped channels. Ultimately, integrated analyses indicated that the gullies originated from weak soil cohesion and intense runoff energy driven by steep slopes. This study provides a resource database for gully remediation efforts in southern Nigeria and tropical sedimentary terrains.

Foraminifera as environmental bioindicators on the Rio Grande Terrace: a preliminary assessment

João Hurst — 2026-06-02

There is still a significant gap in research that integrates foraminiferal data with water mass characterization within the specific context of marine phosphorite prospecting. Therefore, this study investigates the environmental dynamics of the Rio Grande Terrace, a strategic area for phosphorite prospecting on the southern Brazilian continental margin, using foraminifera as environmental bioindicators. Four surface sediment samples collected between 352 m and 623 m depth were washed, dried, and subjected to picking and taxonomic identification of foraminifera. These results were integrated with temperature and salinity (T-S) diagrams. The preliminary results revealed a predominance of white (87.9%) and well-preserved (74%) tests, with a low dissolution rate, suggesting a low-hydrodynamic environment and relatively recent depositions. The assemblage is dominated by planktic species, notably Globigerinoides ruber (45.6%), which is likely associated with the Tropical Water (TW). In contrast, the presence of Globigerina bulloides and Globoconella inflata indicates the influence of South Atlantic Central Water (SACW) and potential upwelling events in the region. Multivariate cluster analysis and nMDS ordination demonstrated high similarity (>95%) among stations 59, 65, and 89, while sample 75 diverged due to the bathymetric gradient. Species clustering, identified a cohesive group consisting of G. bulloides, G. cultrata, T. trilobus, and G. inflata, associated with habitats above 300 mwhereas G. ruber exhibited isolated behavior. The occurrence of G. bulloides reinforces the link between upwelling-driven primary productivity and the genesis of previously mapped phosphorus anomalies. The results indicate a complex oceanographic interaction between tropical and upwelling waters, highlighting the effectiveness of foraminifera as tools for environmental monitoring in mineral exploration activities.

Hydrological analyses for drought assessment in the Meia Ponte River basin, southern Goiás State, central Brazil

Denise Christina Rezende Melo — 2026-06-12

The objective of this study was to evaluate the occurrence and severity of droughts in the Meia Ponte River basin, which belongs to the Paraná Hydrographic Region, considering land use and land cover scenarios with anthropogenic and climate changes. Hydrological data from stations belonging to the National Hydrometeorological Network and the National Institute of Meteorology (INMET) were used, along with a physical and socioeconomic characterization of the basin. Land and water use were assessed, and streamflow and precipitation time series were analyzed using statistical tests and the concept of precipitation elasticity in streamflow. Three drought indices were used in the drought assessment: Standardized Precipitation Index (SPI), Standardized Precipitation-Evapotranspiration Index (SPEI) and Standardized Streamflow Index (SSI). The analysis results indicated significant changes in land and water use over time, due to the expansion of urban areas and increased water withdrawals for irrigated agriculture, along with a reduction in native vegetation. There was a decrease in precipitation and an increase in temperatures, contributing to higher evaporation rates and a decline in relative humidity over the years, which strongly influenced minimum streamflows. The drought assessment identified the driest years in the historical series, showing a progression of droughts from meteorological drought to socioeconomic drought.

Corrigendum to Unveiling geological complexity in the Serra Dourada Granite using self-organizing maps and hierarchical clustering: Insights for REE prospecting in the Goiás Tin Province, Brasília Belt, Central Brazil

Guilherme Ferreira da Silva — 2026-04-15

Refers to: Unveiling geological complexity in the Serra Dourada Granite using self-organizing maps and hierarchical clustering: Insights for REE prospecting in the Goiás Tin Province, Brasília Belt, Central Brazil.

Journal of the Geological Survey of Brazil, Volume 8 (1), April 2025, pages 51-63.

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Following a request from an author/reader regarding the lack of proper attribution to his work in our article, we apologize for the unintentional error and have added the correct credit as follows:

1) Page 53 (caption of Figure 1): Figure 1: a) Location of the Tocantins Province in Central Brazil; b) Study area in the central portion of the Brasília Belt; c) Simplified Geological Map of the Goias Tin Province and the placement of the granites from the Tocantins and Paranã Sub-Provinces (modified from Costa Filho 2020).

2) Page 53 (last paragraph): This is similar to the ages of 571 ± 24 Ma (Teixeira 2002) and 546 ± 11 Ma (Costa-Filho 2020), both using the U-Pb method in monazite and to 530 Ma reported by Hasui and Almeida (1970), in biotite from the Serra da Mesa granite.

Guilherme Ferreira da Silva and co-authors.

Reference: Costa-Filho D.S. 2020. Caracterização mineralógica e proveniência de Monazita-(Ce), Xenotima-(Y) e Zircão de Placer na Província Estanífera de Goiás : estão estes minerais relacionados com o granito tipo-A Serra Dourada? Dissertation. Instituto de Geociências, Universidade de Brasília, Brasília, Distrito Federal, 48 p. http://repositorio.unb.br/handle/10482/39482

Book Review: The Brasília Belt and Tocantins Province, central Brazil: tectonic evolution and role on the São Francisco Craton and West Gondwana build up – an advanced approach

Reinhardt Fuck — 2026-05-11

Recently, Editora Sorian published the substantial book authored by Luiz José Homem D’el-Rey Silva, entitled The Brasília Belt and Tocantins Province, Central Brazil: Tectonic Evolution and Role in the São Francisco Craton and West Gondwana Build-Up – An Advanced Approach.

The author is an experienced researcher and scholar in structural geology and tectonics. Drawing on his own detailed studies conducted in several areas of the Brasília Belt, as well as in other orogenic belts of the Tocantins Province and various regions along the margins of the São Francisco Craton, and integrating the extraordinary body of knowledge accumulated over the last fifty years by geologists and geophysicists through numerous geophysical, geological, geochemical, geochronological, and related studies carried out in Central Brazil, the author has produced a significant work on the construction and evolution of the continental crust that eventually formed the western portion of the Gondwana Supercontinent during the late Proterozoic and early Phanerozoic eras.