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- Geological correlation of Neves-Corvo Mine and Pomarão Antiform sequences (Iberian Pyrite Belt, Portugal)Publication . Albardeiro, Luís; Matos, João Xavier; Mendes, Márcia; Solá, A. Rita; Pereira, Zélia; Morais, Igor; Salgueiro, Rute; Pacheco, Nelson; Araújo, Vítor; Oliveira, José TomásABSTRACT: A geological correlation between Neves-Corvo (NC) and Pomarão antiforms is attempted. These regional scale major sequences are easily correlated but, at local scale, facies and age differences stand out. Stratigraphy includes: i) the Phyllite-Quartzite Group with identical paleogeography setting and similar late Famennian ages for uppermost levels (LL to LN miospore biozones in Pomarão and NC respectively). ii) the Volcano-Sedimentary Complex shows some discrepancyconcerning the age distribution of the felsic volcanic rocks (ca. 356-330for Pomarão and ca. 365-346 Ma for all NC area) while sediments rangefrom mid-Famennian to late Visean age (VH to NM Miospore Biozonefor NC). iii); the Baixo Alentejo Flysch Group (late Visean NM MiosporeBiozone onwards in NC), covering the previous sequences and beingslightly older than the uppermost volcanic rocks of Pomarão. Thecorrelation between these two structures is supported by geology andisotopic/biozone ages and favours exploration scenarios in both regions.
- Áreas potenciais de Portugal para recursos minerais do domínio públicoPublication . Carvalho, Jorge; Filipe, Augusto; Gonçalves, Pedro; Lisboa, Jose; Matos, João Xavier; Batista, Maria Joao; Salgueiro, Rute; de Oliveira, Daniel Pipa SoaresSUMMARY: Land-use planning is decisive for granting access to mineral resources. During the work to identify the actions to be taken for preparing the National Strategy for Geological Resources, a map of mineral potential areas for Portugal was produced. It provides the starting point scenario needed for the implementation of a methodology aimed at the delineation of mineral safeguarding areas.
- Proyecto GEO_FPI, cartografía de la Zona Surportuguesa (ZSP). Datos preliminares de un estudio geocronológico U-PbPublication . Díez-Montes, Alejandro; Matos, João Xavier; Valverde-Vaquero, Pablo; Solá, A. Rita; Beranoaguirre, Aratz; Albardeiro, Luis; Salgueiro, Rute; Morais, Igor; Montero, P.; López, M. T.RESUMEN: La ZSP es la unidad geotectónica más al suroeste del Orógeno Varisco y se consideran los siguientes dominios: Pulo do Lobo (Frasniense inferior y Fameniense superior), Faja Pirítica Ibérica (Givetiense-Viseense superior), Grupo Flysch Baixo Alen tejo (Viseense superior-Moscoviense superior) y Grupo Suroeste (Estruniense-Bashkiriense medio). En el proyecto GEO_FPI se ha prestado especial atención a la Faja Pirítica Ibérica, ya que es una de las provincias metalogenéticas más importantes del mundo, con depósitos de sulfuros masivos (VHMS) e importantes recursos de Cu, Zn, Pb, Ag, Au, Sn, In, Se, Ge. Se ha realizado un trabajo de campo en común en la región fronteriza de España y Portugal para permitir una mejor inte gración y correlación de los datos geológicos y cartográficos. Además, se han seleccionado 31 afloramientos donde se han recogido muestras para realizar un estudio de geocronología de U-Pb en circón. Los datos de edad obtenidos son importantes para restringir las estructuras geológicas de la Faja Pirítica Ibérica que albergan la mineralización masiva de sulfuros y, por otra parte, mejoran la visión geotectónica de toda la ZSP
- Mineralizações de magnetite e sulfuretos de Monges (Santiago do Escoural, Montemor-o-Novo), Vale de Pães (Cuba-Vidigueira) e Orada (Pedrógão, Serpa) : Síntese de ensaio comparativoPublication . Salgueiro, Rute; Mateus, António; Inverno, CarlosAs mineralizações Monges (Montemor-o-Novo), Vale de Pães (Cuba-Vidigueira) e Orada (Serpa), incluídas na Faixa Magnetítico-Zincífera da Zona de Ossa-Morena (ZOM), evidenciam características mineralógicas e geoquímicas diferentes, não obstante partilharem uma constituição dominada por magnetite ± sulfuretos (pirite, pirrotite e calcopirite). A diferença é tanto mais notória quando se compara Monges (possivelmente um sistema misto do tipo SEDEX-VMS) com Vale de Pães ou Orada, as duas últimas representando sistemas do tipo Skarn-Fe(Mg/Ca). Os dados disponíveis permitem ainda posicionar o desenvolvimento destes sistemas mineralizantes em contextos geológicos distintos, correlacionáveis com diferentes estádios da evolução geodinâmica/metalogenética da ZOM.
- Processamento de materiais termoelétricos baseados na tetraedrite usando minério de tetraedrite-tenantitePublication . Esperto, Luís; Figueira, Isabel; Mascarenhas, João; Salgueiro, Rute; Silva, Teresa; Lopes, E.B.; Gonçalves, António Pereira; Correia, J.B.; de Oliveira, Daniel Pipa Soares; Almeida, P.; Neves, FilipeRESUMO: O desenvolvimento e implementação de tecnologias com baixo potencial de aquecimento global e energeticamente eficientes requer uma contínua inovação na área dos materiais para a energia. Nesta estratégia insere-se a pesquisa sobre o processamento de materiais termoelétricos baseados na tetraedrite. No presente trabalho procede-se à avaliação da viabilidade da incorporação direta, sem qualquer pré-tratamento, de minério da série tetraedrite-tenantite no processamento de materiais à base de tetraedrite por síntese mecanoquímica. Para tal prepararam-se misturas de pós contendo diferentes rácios de amostras de tetraedrite sintética, também obtida por síntese mecanoquímica, e de amostras de minério, recolhidas na mina de Neves-Corvo e na escombreira da mina do Barrigão. A caraterização estrutural e microestrutural dos materiais processados após 1 h e 2 h de síntese mecanoquímica permitiu verificar a formação de um composto constituído por tetraedrite-tenantite-(Fe) como fase principal, independentemente do minério de origem. Estes resultados são uma indicação do sucesso da abordagem seguida.
- New data on nodular monazite from Monfortinho (Idanha-a-Nova, Portugal)Publication . Salgueiro, Rute; Inverno, Carlos; De Oliveira, Daniel Pipa Soares; Guimarães, Fernanda
- Levelling geochemical datasets as a tool to overcome boundary features in data applied to mineral explorationPublication . Batista, Maria Joao; de Oliveira, Daniel Pipa Soares; Salgueiro, RuteRESUMO: A existência de um elevado número de análises químicas produzidas durante as campanhas de prospeção geoquímica ao longo de décadas, deu origem a um elevado número de resultados analíticos produzidos com diferentes métodos analíticos, protocolos de amostragem e meios amostrais. Assim sendo, é necessário fazer o nivelamento destes resultados analíticos no sentido de os tornar comparáveis e, assim, aproveitar o potencial de informação geoquímica de áreas contíguas. Neste estudo foi utilizada uma técnica de nivelamento com base em bandas testadas com várias larguras entre as cartas de escala 1:25.000, respetivamente a 293/294 e 305/306, da região da Beira Baixa onde se amostraram sedimentos de corrente durante o projeto “Terras Raras”. Estas amostras foram analizadas pelos mesmos métodos analíticos e no mesmo laboratório, mas observaram-se efeitos de bordadura de carta. Estas técnicas de nivelamento devem ser adaptadas aos dados que queremos comparar e no caso presente observou-se o desaparecimento do efeito de bordadura entre as cartas 293/294/305/306.
- Levelling geochemical datasets as a tool to overcome boundary features in data applied to mineral explorationPublication . Batista, Maria Joao; de Oliveira, Daniel Pipa Soares; Salgueiro, Rute; Inverno, CarlosABSTRACT: The existence of a large number of chemical analyses resulting from decades of geochemical exploration campaigns, yields huge numbers of analytical results produced with different analytical methods, sampling protocols and sampling means. Therefore, it is necessary to level these analytical results to make them comparable and thus take advantage of the potential of geochemical information from contiguous areas. In this study, a levelling technique was used on geochemical datasets of tested bands between the 1:25 000 scale maps, 293/294 and 305/306 sheets, respectively, from the Beira Baixa region where stream sediments were sampled during a project for rare earth elements exploration. These samples were analysed for lanthanum by the same analytical methods and in the same laboratory, but in different periods and the border effects were observed. These levelling techniques must be adapted to the data to be compared and in the present case the disappearance of the border effect of the analytical results of 293/294 and 305/306 topographic sheets was observed.
- Geochemistry of Iberian Pyrite Belt Portuguese sector massive sulfide deposits-related volcanic rocks. Considerations on hydrothermal alteration, petrology and tectonic evolutionPublication . Morais, Igor; Albardeiro, Luís; Batista, Maria Joao; Matos, João Xavier; Solá, A. Rita; de Oliveira, Daniel Pipa Soares; Salgueiro, Rute; Araújo, Vítor; Pacheco, NelsonABSTRACT: A geochemical compilation database of the main volcanic units of the Volcano-Sedimentary Complex (VSC) of the Iberian Pyrite Belt (IPB), one of the largest provinces of massive sulfides on a global scale, is presented and discussed. For this purpose, we used several mineral exploration rock geochemistry databases from six IPB areas, namely Cercal, Lagoa Salgada, Lousal, Aljustrel, Neves-Corvo and Chança, regarding unaltered/hydrothermaly altered felsic volcanic units interbedded in the Famennian-Late Visean volcano-sedimentary sequences of the VSC. Volcanic rocks within the Phyllite-Quartzite Formation (Givetian-Famennian) IPB basement were also considered. From this, Neves-Corvo sector rhyolites (Rhyolite type 1 and 2) present the most intense hydrothermal alteration, directly related with the age of mineralization and coeval with hosted VSC sedimentary formations. Similar cases were also observed in the volcanic units hosting Lagoa Salgada, Chança and Aljustrel Volcanic-hosted massive sulfide (VHMS) deposits. The variety of felsic and intermediate volcanic rocks in the IPB (and within each sector) reflect different petrogenetic processes and/or distinct crustal sources. Application of Zr vs TiO2 binary diagrams allows to define three main trends of andesitic (Lagoa Salgada and Chança sectors), dacitic-rhyodacitic (Aljustrel sector) and rhyolitic (Cercal, Neves-Corvo, Aljustrel and Lousal sectors) composition. Cercal rhyolites are the most evolved felsic rocks (Zr/TiO2 ≈ 1562), followed by Neves-Corvo rhyolites (Zr/TiO2 ≈ 936), Lousal (Zr/TiO2 ≈ 845) and Aljustrel (Zr/TiO2 ≈ 840). In addition, four distinct compositional clusters can be distinguished based on Al2O3/TiO2 vs Zr/TiO2 and Al2O3/Zr vs TiO2/Zr ratios according to its nature as, rhyolitic, rhyodacitic/dacitic and andesitic, probably reflecting differential partial melting rates. Ybn vs La/Yb(n) diagram ratio indicates that Neves-Corvo (mainly 2 types of rhyolites), Aljustrel (Tufo da Mina rhyolitic unit), as well as Lagoa Salgada sector rhyolites are projected along FIIIa and FIIIb rhyolite fields considered of higher metalliferous potential in the IPB, once their petrogenetic processes are considered ideal to trigger, sustain and host hydrothermal systems and consequently VHMS deposits. Future work, combining geochemical characterization of each volcanic unit with their stratigraphic positioning, is essential in order to achieve a correct correlation between the different sectors and, is therefore, a useful tool in IPB mineral exploration and drill-hole data correlation.
- Alluvial xenotime and heavy minerals assemblage from the northern edge of Nisa-Albuquerque Batholith, eastern Portugal : provenance and geochemical implicationsPublication . Salgueiro, Rute; Rosa, Diogo; Inverno, Carlos; de Oliveira, Daniel Pipa Soares; Solá, A. Rita; Guimarães, FernandaAlluvial xenotime and heavy minerals assemblage from the northern edge of Nisa-Albuquerque Batholith, eastern Portugal : provenance and geochemical implications / Rute Salgueiro... [et al.]. - Amsterdam : Elsevier, 2014. - [18] p. : il., 13 figuras e 8 tabelas ; 30 cm The xenotime-bearing heavy mineral assemblages present in the alluvial samples from Vila Velha de Ródão, Nisa, Póvoa e Meadas and Sto. António das Areias, localized in the northern edge of Nisa-Albuquerque Batholith, Eastern Portugal, were studied in detail. The insights for mineral provenance came from the analysis of the drainage network and from the composition of the regional alluvial samples and outcropping lithologies. Since xenotime is a mineral with economic interest, the motivation of the current work is its contribution for exploration studies, considering the potential information contained in the alluvial samples. In the study region, the alluvial heavy minerals and their morphology reflect clearly the mineralogy and relative distance to their source, respectively. In alluvial samples with direct provenance from the Nisa granite (late Carboniferous), the increase in xenotime concentration and decrease in monazite, apatite, zircon, ilmenite and iron oxide concentration, from W (Nisa) to E (Sto. António das Areias), matches the increase in P2O5 and decrease in REE, CaO, Zr, TiO2, and Fe2O3 contents in granite rocks. The geochemical signature of xenotime studied reveals an igneous source, characterized by the characteristic strong Eu negative anomaly in REE patterns. Their YPO4 values (72–78 mol%) are similar to xenotime from Erzgebirge (Germany) granites. The high values of Y/Ho (50–71) and, in some cases, downward kinks at Ho in REE plots, suggest generation in late stages of crystallization and association with a siliceous evolved magmatic system. The slight decrease in HREE contents in xenotime, from W to E, and Ho anomalies in the normalized REE pattern are similar to those identified in the Nisa granite, which supports the sourcing of xenotime from these granitic rocks. The genetic development of the batholith chemical zonation (more evolved to E) seems to have favoured the generation of xenotime instead of apatite, monazite and zircon, in the eastern end area (Sto. António das Areias). Supporting the geochemical signature, the alluvial zircons also display morphological typologies that are compatible with provenance from peraluminous granites formed at temperatures of 600–700 °C, possibly from the Nisa granite. Since all xenotime grains show the same magmatic affinity, this leads to the hypothesis that the xenotime from the Vila Velha de Ródão sample, with provenance from Cenozoic sedimentary rocks, has been transported to this northern area, after been disaggregated from Nisa batholith granites, most probably by braided anastomosing and erratically sandy channels, that explains its actual position in the opposite bank of the Tagus river. This phosphate has been deposited with other sediments in tectonic depressions and subsequently included in the formation of sedimentary rocks. The greater development of Ca, Th and U phosphate inclusions/substitutions in these xenotime grains can be explained by the chemical mobility provided during all the geological processes.