GEOCIÊNCIAS
URI permanente desta comunidade:
Navegar
Percorrer GEOCIÊNCIAS por Domínios Científicos e Tecnológicos (FOS) "Ciências Naturais::Ciências da Terra e do Ambiente"
A mostrar 1 - 10 de 49
Resultados por página
Opções de ordenação
- 3D Magnetic Inversion in Angola: Serra da Neve Alkaline Complex and Jamba Itabirites case studiesPublication . Machadinho, Ana; Represas, Patricia; Alves, Daniela; Cordeiro, Domingos; Carvalho, João; Lopes, R.; Caessa, Paulo; Pereira, L. F; Osório, A.ABSTRACT: Demanding and speculative economies make it imperative to search for new areas of mineral exploration. Angola’s geological diversity presents an enormous potential for mineral resources. This potential can be assessed by applying different methods, such as geophysical prospecting, to discover new potential targets of areas to explore. For many years, the magnetic method has been successfully used in mineral exploration. In this work we apply a 3D magnetic inversion technique to aeromagnetic data in two different study areas. The Serra da Neve alkaline complex (SNAC) represents a potential source for rare earth elements (REE) and the Jamba itabirites provides metallic mineral deposits with iron and gold mineralizations. In both case studies, whether concerning alkaline intrusions or itabirites deposits, their magnetic properties are characterized by strong magnetic anomalies clearly delineated on magnetic anomaly maps. The high magnetic susceptibility (k) contrast between these target structures and the host rocks allowed us to obtain a coherent three-dimensional geometry for the SNAC structures and the itabirites deposits. The magnetic inversion technique also provided magnetic vector inversion (MVI)susceptibility values estimation for constituent lithologies, as well as the shape and size of the studied structures and deposits. The results demonstrate the effectiveness of the magnetic method for the detection and characterization of target areas, offering an innovative technique to identify potential areas in mineral resources exploration.
- Acesso à informação via geoPortal da Energia e Geologia [Comunicação oral]Publication . Quental, Lídia; Patinha, Pedro; Pereira, Aurete
- AfricaMaVal : Mineral Potential Mapping Study of European Critical Raw Materials (ECRM) of Africa [Resumo]Publication . Fullgraf, Thomas; Marques Prazeres, Cátia; Gonçalves, Pedro; Callec, Yannick; Fortes, Carla; Represas, Patricia; Vella, Alex; Guillaneau, Jean-Claude; de Oliveira, Daniel Pipa SoaresABSTRACT: The AfricaMaVal project, a 3.5-year initiative coordinated by the French Geological Survey (BRGM), fosters sustainable EU–Africa partnerships in the critical raw materials (CRM) sector. With 18 partners from 11 countries, it promotes responsible mineral sourcing for European industries while supporting Africa’s sustainable development. Work Package 1 (WP1), “Supply Potential,” led by the Portuguese Geological Survey (LNEG), assesses and maps African supply potential for European Critical Raw Materials (ECRM) through a harmonized, INSPIRE-compliant database. BRGM has developed machine learning (ML) algorithms for mineral resource assessment over the past 20 years, applied at scale since 2022. Within WP1, prospectivity maps for selected ECRMs were generated in ten countries, drawing on BRGM datasets, including 1:10M geological and structural maps and over 55,000 mineral occurrences.
- Age dependent variation of the magnetic fabric of dike swarms and implications for the volcanic structure of ocean islands: the example of the Maio Island, Cabo Verde archipelagoPublication . Moreira, Mário; Mata, João; Madeira, José; Represas, Patricia; Martins, SofiaABSTRACT: Magnetic fabric analysis of dikes is a powerful technique when assessing magma transfer processes. This study presents an integrated analysis combining magnetic susceptibility and anisotropy of magnetic susceptibility, magnetic mineralogy, geochemistry and new 40Ar/39 Ar dating of dikes intruding formations ranging from the Lower Cretaceous to the Miocene on the island of Maio, in the Cabo Verde archipelago. We show that the dikes, dated at ≈9.2 Ma, intruding the younger Miocene Casas Velhas formation, display a Ti-rich titanomagnetite composition, higher whole-rock TiO2 content and very high magnetic anisotropy. They are clearly distinguished from the dikes, ranging in age from ≈9.3 to 11.3 Ma, intruding older formations, which show a predominantly Ti-poor titanomagnetite composition with multiple magnetic phases, lower whole-rock TiO2 concentration, higher range of magnetic susceptibilities and very low anisotropy. Magnetic fabric is predominantly normal with no significant imbrication relative to the dike margins. Numerical analysis of fabric shows a dominant coaxiality between the magnetic lineation and the preferred orientation of opaques and phenocrystals suggesting that magnetic lineation is, therefore, the proxy of the magmatic flow axis orientation. Based on the orientation of the magnetic fabric, we infer that magmatic flow within the studied dikes is predominantly vertical. The differences observed between the younger dikes and all other dikes may be related to magma sourced from distinct magma chambers. One, probably shallow, underneath the Casas Velhas fm in the southwest of the island, which would explain the very high values of magnetic anisotropy and the inferred vertical flow, and another located in a central position in the island, responsible for the dikes intruding the older formations. The location of such magma reservoirs and the dikes ages suggest a hypothetical migration with age of the magmatic sources that fed the dikes from the central part of the island to the southwest region. The magnetic and mineralogical heterogeneities of the dikes intruding older Lower Cretaceous formations may also be a result of a wider age range of the intrusions.
- Application of the Play-Based Exploration Pyramid Approach Adapted to Deep Geothermal Resource Mapping at the European Scale in the EU GSEU ProjectPublication . Herms, Ignasi; Caldera, N.; Arnó, Georgina; Canteli, P.; García-Crespo, J.; Carrión, E.; Ramalho, Elsa; Carvalho, João; Nádor, A.; Steiner, C.; Janku, L.; Koevoets, M. J.ABSTRACT: This work introduces version 1.0 of the Pan-European Atlas of Sustainable GeoEnergy Capacities (SGC), developed within the GSEU (Geological Service for Europe) project. The Atlas applies the Play-Based Exploration Pyramid (PBEP) approach to harmonize and standardize the assessment of deep geothermal resources across Europe. The methodology follows a multiscale structure—Levels 0 to 3—that refines geothermal understanding from regional geosystems to detailed local targets. Version 1.0 has been published in spring 2025 via the European Geological Data Infrastructure (EGDI) and includes Levels 0 and 1. Level 0 provides public data from boreholes and thermal springs, serving as the base for Level 1, which maps favorable areas for geothermal exploration using Geothermal Play Typing (GPT). The release includes a catalogue of near 400 factsheets describing each GPT unit, along with a metadata report. Future versions (2.0 in 2025 and 3.0 in 2026) will introduce deeper layers of detail. Level 2 will identify potential geothermal reservoirs using 1D stochastic estimations of geothermal and heat storage potential. Level 3 will compile existing 2D/3D maps and models for detailed local-scale reservoir assessments. Altogether, the Atlas supports Europe's energy transition by enhancing knowledge and visibility of its deep geothermal potential.
- Arquivo de lâminas e superfícies polidas do LNEG, uma coleção de valor científico nacional: LAMINOTECA 1.0 do LNEGPublication . Pereira, Zélia; Quental, Lídia; Jorge, Micael; Teixeira, Rui; Patinha, Pedro; Xavier Matos, João Manuel; Mesquita Soares, Sofia; Silva Mendes, Márcia Cristina; Pereira, Aurete; de Oliveira, Daniel Pipa Soares; Matos, Luísa; Carvalho, Cristina Isabel Paulo; Dias, RubenRESUMO: O arquivo histórico do Laboratório Nacional de Energia e Geologia (LNEG) engloba um espólio científico resultante de quase 180 anos de atividade geológica e mineira, o que constitui um banco de dados excecional e um verdadeiro repositório geológico nacional. No âmbito das áreas de missão do LNEG, consta a preservação, tratamento e disponibilização deste património único. Este espólio é considerado património científico nacional, com significado histórico e fundamental à investigação estratégica do país e de enorme valor económico. Todavia, é pois, necessário que as coleções existentes se encontrem devidamente organizadas e preparadas para serem disponibilizadas online através da plataforma geoPortal da Energia e Geologia (GEG), infraestrutura online do LNEG. E, para a concretizar este objetivo, será necessário criar e desenvolver um centro de dados digital sobre coleções especificas, que facilite e promova a consulta da informação existente. O projeto LAMINOTECA 1.0 visa estabelecer um novo modelo de organização e valorização do espólio histórico do LNEG, parte integrante do repositório geológico nacional. Paralelamente, promove o reforço funcional do GEG, enquanto plataforma digital central institucional e de acesso público, para disponibilização estruturada e georreferenciada das coleções temáticas, com destaque para as geológicas e mineiras. Esta iniciativa facilitará a pesquisa e consulta especializada, contribuindo para o avanço científico, educativo e económico. Espera-se que este projeto apoie, no futuro, atividades de I&D aplicadas às áreas estratégicas do LNEG, nomeadamente o Plano Nacional de Cartografia e o Plano Nacional de Prospeção no âmbito do Ato das Matérias Primas Críticas, reconhecendo o valor económico e territorial do conhecimento geológico e fomentando a especialização inteligente em petrografia, paleontologia e mineralizações.
- Cartografía Geológica del Plan Nacional de Geología de Angola (PLANAGEO)Publication . Merino-Martínez, E.; Rodrigues, José Feliciano; Martín-Banda, Raquel; Francés, Alain Pascal; Feria, María Carmen; López-Bahut, T.; Ferreira, Ezequiel; García-Lobón, J. L.; Gumiel, J. C.; Cuervo, I.; Victorino, Américo da Mata; Manuel, JoséRESUMEN: La cartografía geológica fue la actividad central en la que se basó el Plan Nacional de Geología de Angola (PLANAGEO). Los trabajos de cartografía geológica realizados por el consorcio UTE PLANAGEO (IGME/LNEG/IIA) en el sur de Angola (476.512 km2), desarrollados entre 2016 y 2020, comprendieron 44 cartas a escala 1:250.000, 15 cartas a escala 100.000, 8 mapas de síntesis a escala 1:500.000 y 4 mapas geotemáticos a escala 1:1.000.000. A partir de estos trabajos, fueron distinguidos diversos dominios geológicos en el sur del Escudo de Angola, delimitados por macroestructuras bien definidas en los modelos geofísicos. Los mapas y sus memorias asociadas reúnen todo el conocimiento generado durante PLANAGEO, siendo un manual de referencia geológica y un modelo para futuros estudios geológico-mineros. Los mapas geológicos realizados constituyen la base de una infraestructura regional de conocimiento geológico de la región sur de Angola, y proporcionan información básica para el aprovechamiento óptimo del territorio y desarrollar el potencial de los recursos naturales del país.
- Chemical and Mineralogical Characterization ofWaste from Abandoned Copper and Manganese Mines in the Iberian Pyrite Belt, Portugal: A First Step Towards the Waste-to-Value Recycling ProcessPublication . de Oliveira, Daniel Pipa Soares; Silva, Teresa; Morais, Igor; Fernandes, JoãoABSTRACT: This study examines the chemical and mineralogical composition of waste materials from abandoned copper and manganese mines in the Iberian Pyrite Belt, Portugal, as a first step toward their potential recycling for critical and strategic raw materials (CRM and SRM). Using portable X-ray fluorescence (pXRF) and other analytical techniques, this research highlights the presence of valuable elements, including copper, manganese, and rare earth elements, in concentrations significantly above their crustal abundance. The findings underscore the dual potential of these wastes: as sources of secondary raw materials and for mitigating environmental hazards such as acid mine drainage (AMD). Recovered materials include chalcopyrite, pyrolusite, and rhodochrosite, with critical elements like cobalt, lithium, and tungsten identified. pXRF proved to be a reliable, cost effective tool for rapid field and laboratory analyses, demonstrating high precision and good correlation with standard laboratory methods. The study emphasizes the importance of characterizing historical mining waste to support a circular economy, reduce reliance on foreign material imports, and address environmental challenges. This approach aligns with the European Union’s Critical Raw Materials Act, promoting sustainable resource use and the recovery of strategic resources from historical mining sites.
- Ciencia ciudadana en el análisis de peligros geológicos en el Área Atlántica [Resumo]Publication . Montoya-Montes, Isabel; Galindo, Inés; Sanchez, Nieves; Jaud, Marion; Le Dantec, Nicolas; Pinto, Cláudia; Ferreira, M. A.; Parker, Kieran; Lemon, Kirstin; Rodrigues, Domingos; Quental, Lídia; Ramalho, Elsa; Gonçalves, Pedro; Cruz-Pérez, N.; Ortega, A.; Holohan, Eoghan; Correia, Vítor; Jeremias, Filipe Telmo; Gomes, Rui CarrilhoRESUMEN: La participación ciudadana constituye la piedra angular común de los cinco Observatorios piloto de peligros geológicos (movimientos en masa, terremotos, inundaciones fluviales y costeras, riesgos geotécnicos y erosión costera) implementados en cuatro países del Área Atlántica en el marco del proyecto AGEO INTERREG, con varias iniciativas de divulgación llevadas a cabo para mejorar la concienciación de los ciudadanos sobre los peligros geológicos. En este contexto, el logro notable de AGEO reside en el desarrollo de herramientas estandarizadas capaces de satisfacer las numerosas necesidades de estos pilotos, de modo que tanto los ciudadanos como los colaboradores expertos tengan acceso a canales de comunicación que les permitan informar sobre la ocurrencia de eventos de peligros geológicos. Además, la utilización de productos y servicios de emergencia del programa europeo Copernicus asume un papel importante en el establecimiento y funcionamiento de los Observatorios. Debido a su adaptabilidad en todo el variado espectro de pilotos de AGEO, estas herramientas prometen una integración perfecta en posibles futuros observatorios ciudadanos de riesgos geológicos y por tanto una contribución a la mejora de los sistemas de gestión de riesgos.
- Construction raw materials in Timor Leste and sustainable developmentPublication . Carvalho, Jorge; Lisboa, JoseABSTRACT: Timor Leste is the newest and one of the poorer nations in the world. One of its main challenges that could lead to poverty reduction is the reconstruction and maintenance of the infrastructures that were almost completely destroyed after its independence referendum. To achieve this, there is an imperative need for construction raw materials in a country where the extractive industry is scarce and artisanal. Available geological studies deal with the island’s geology and tectonic evolution or its oil and gas potentialities. Very few broach other geological resources. A general study of the country’s territory demonstrates that Timor Leste possesses large resources in clays, limestones and sand and gravel, which can support small- to large-scale raw material extractive industries. Some selected areas have been the target of more detailed study: Venilale and Aileu, with resources for structural ceramics and whiteware respectively, and Beheda, where a crinoid-rich limestone crops out, with potential for usage as ornamental stone. These resources are suitable for non-sophisticated small-scale mining operations that should be able to accomplish environmental and social liabilities. No public policy exists for the management of these mineral resources, which is essential for the sustainable development of Timor Leste.