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- HidrogeologiaPublication . Pereira, Ana Paula Teixeira
- Improving the seismic hazard evaluation of the Lisbon and Lower Tagus Valley areaPublication . Carvalho, João P. F.; Pinto, Carlos C.; Costa, M.; Heleno, S.; Silva, M.; Rabeh, Taha; Cooksley, G.; Carrilho, F.The Lisbon and surrounding area of the Lower Tagus Valley has experienced in the past the effects of several moderate sized earthquakes that caused significant damage and destruction. They have been attributed to local sources, though in some cases the source remains to be located. The lack of outcrops in the flat lying Quaternary terrains, the low slip-rates of the area in connection with sedimentation and erosion rates that erase surface ruptures are among the causes of a poor association between faults and seismicty, which has opened way to geophysical studies. Seismic, potential-field and seismicity data have been recently used to improve the seismic hazard evaluation of the area. In this work we complement these studies with DTM and PSInSAR data with the purpose of obtaining an accurate evaluation of the seismic hazard of the study area. The correlation of improved epicentre locations with major fault zones located from the above mentioned data shows that we have progressed in the understanding of the earthquake sources in the region. Some structures show no apparent relationship with present-day seismicity but some are known to be active into the Quaternary. Further geophysical and geological studies are required to understand the causes.
- A soil classification for seismic hazard assessment and mitigation of the AlgarvePublication . Carvalho, João P. F.; Dias, Ruben Pereira; Pinto, Carlos C.; Leote, Jaime; Victor, L. MendesThe Algarve province of Portugal is located near the E-W Eurasia-Africa plate boundary. It is characterized by a moderate seismicity, with some important historical earthquakes causing important damage and economical losses. Not only has it suffered the effects of large plate boundary events but also the impact of local onshore moderate-sized earthquake sources. The seismic hazard evaluation and mitigation of the area is therefore of great importance to the local populations and the large number of tourists that frequent the region. This paper focuses the evaluation of the most interesting and useful geotechnical near-surface parameters and a soil classification. The classification based upon the European Code 8 for civil engineering and SPT bedrock data, was carried out for land use planning and design of critical facilities. P-wave and S-wave seismic velocities were obtained through the acquisition, processing and interpretation refraction profiles. Hundreds of SPT parameters from available boreholes drilled for engineering and water supply were used and subsoil classification based on geophysical and geotechnical parameters is presented. Other parameters, such as Vp/Vs ratios and the Poisson coefficient were estimated and were computed to provide information for future site effect studies. The experimental procedure tested here is relatively fast, economical and easy to perform and can be useful to estimate soil microzoning and seismic hazard mapping in the absence of local earthquake records.
- New data on the late Famennian miospore assemblage of the Cercal Anticline, westernmost Iberian Pyrite Belt area, PortugalPublication . Pereira, Zélia; Matos, João Xavier; Fernandes, Paulo; Oliveira, José TomásThe Cercal Anticline (CA) is located in the westernmost region of the Iberian Pyrite Belt (IPB). The exposed stratigraphic sequence includes, in ascending order, the Volcano-Sedimentary Complex (VSC) followed by the Xistos das Abertas Fm, which passes gradually to the flysch sequence of the Mira Formation (Carvalho, 1976). The VSC is composed from base to top by: Felsic Volcanics (Vα), that comprehends lavas, pumice and volcaniclastic beccias with intercalations of volcanogenic shales; diabases and intermediate/basic subvolcanics (Vβ); jaspers and the S. Luís Formation (SL), a unit composed of shales, phyllites, siliceous shales and volcanogenic sediments. About 500m NW of São Luís village, at the base of this last unit, brachiopods ascribed to the late Strunian were found (Quiring, 1936). This determination led Carvalho (1976) to assume that the volcanics of the VSC are older than the Strunian, meaning so that this volcanism is the oldest in the Portuguese IPB. The stratigraphic succession of the CA is still poorly constrained, in terms of lithostratigraphy and age. In fact, three boreholes carried out in the hinge zone of the anticline by the Elf Aquitane company, about 1km NW of São Luis village, showed that below the felsic volcanics a thick (>250m) succession of dark shales and siltstones occur. These shales yielded very well preserved specimens of Grandispora echinata together with Ancyrospora spp., Apiculiretusispora sp., Auroraspora macra, Cristicavatispora dispersa, Diducites poljessicus, D. mucronatus, D. versabilis, Emphanisporites annulatus, Grandispora cornuta, Punctatisporites spp., Retispora cf. macroreticulata, Retusotriletes phillipsii, R. planus, R. triangulatus, R. rugulatus, Rugospora explicata and R. radiata. This assemblage indicates the VH Biozone of late Famennian age. It is similar to those found in shales interbedded in felsic volcanics in several regions of the Portuguese Pyrite Belt (Neves Corvo Mine, Albernoa Anticline, São Domingos Mine). Palynostratigraphic research in the CA is currently still in progress. However, these preliminary results show that the age of the CA felsic volcanics is similar to that obtained in the northeastern branches of the Portuguese Pyrite Belt and no prove that the volcanism migrated in time to the NW, as suggested by Carvalho (1976), could be detected.
- U-Pb geochronology of felsic volcanic rocks hosted in the Gafo Formation, South Portuguese Zone : the relationship with Iberian Pyrite Belt magmatismPublication . Rosa, Diogo; Finch, A. A.; Andersen, T.; Inverno, Carlos
- Missão geológica de Angola : contextos e emergênciaPublication . Brandão, José Manuel Moraes ValeEmbora desde os finais do século XIX se viessem a realizar mais intensamente diversos estudos, Angola carecia de um trabalho sistemático de reconhecimento das suas características e potencialidades geológico-mineiras. O grande passo para a constituição da primeira estrutura permanente com aquelas finalidades foi dado em 1921 por Norton de Matos, com a criação da "Missão Geológica de Angola". Durante os anos em que funcionou, não obstante os seus limitados recursos, a Missão produziu um importante trabalho que culminou com o lançamento da primeira carta geológica geral do território em 1933.
- U-Pb detrital zircon ages in synorogenic deposits of the NW Iberian Massif, Variscan belt : interplay of Devonian-arboniferous sedimentation and thrust tectonicsPublication . Martínez Catalán, José R.; Fernández-Suárez, Javier; Pinto de Meireles, Carlos Augusto; González-Clavijo, Emilio J.; Belousova, Elena; Saeed, AyeshaDetrital zircons from Devonian and Carboniferous synorogenic flysch deposits occurring in an imbricate stack have been dated by laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) to: (1) obtain a maximum depositional age to constrain the maximum age limit for thrusting of exotic terranes in the NW Iberian Massif; (2) correlate the zircon age populations with published ages in nearby units to establish their possible source areas. The maximum depositional ages are Late Devonian for rocks high in the structural nappe pile (Gimonde Formation), in accordance with palynomorph dating, and around the Devonian–Carboniferous boundary for structurally lower samples (San Vitero Formation). Used in conjunction with previously published ages, the new ages are interpreted in terms of the advance of the thrust system responsible for the emplacement of exotic terranes upon the Iberian autochthon during the Variscan collision. Early Variscan zircon population ages indicate the exotic terranes as the source of synorogenic sediments, whereas their scarcity suggests derivation from the Iberian autochthon. One of the samples analysed lacks Variscan detrital zircons; this feature, together with the absence of an Early Palaeozoic zircon age population, puts into question its synorogenic character and suggests that the sample may be representative of the preorogenic parautochthon.
- Electrólitos poliméricos para sistemas electroquímicos de energiaPublication . Plancha, Maria JoãoNa primeira parte do trabalho são sintetizados filmes poliméricos de poli(óxido de etileno) dopado com cloreto de zinco, iodeto de zinco, cloreto de níquel ou iodeto de níquel. Os filmes, com espessuras na gama 50-100μm, são caracterizados morfológica e microestruturalmente, procedendo-se também à análise do comportamento térmico dos mesmos. O estabelecimento de diagramas de equilíbrio de fases permite prever termodinamicamente a melhor relação estrutura/condução iónica. Esta propriedade é estudada na gama 20-155ºC, determinando-se a influência da temperatura e da concentração salina na condutividade dos electrólitos. A caracterização electroquímica prossegue com a determinação dos números de transferência catiónica, que permitem identificar o tipo de transportadores de carga. Factores como a possibilidade de existência de associação iónica nos electrólitos PEO-MX2, são considerados nos estudos electroquímicos. Os domínios de estabilidade electroquímica são analisados em função da temperatura, determinando-se tensões de decomposição e tensões de descargas catódica e anódica. Na última fase deste trabalho é escolhido o electrólito polimérico que apresenta melhores propriedades para incorporação numa bateria totalmente sólida. As minicélulas, com cátodos de inserção baseados em Nb2O5 e o PEO4ZnCl2 como electrólito, são estudados a 55ºC. A capacidade de retenção de carga e o comportamento das baterias a ciclos de descarga/carga são analisados.
- Ordovician and Silurian geological heritage in protected natural areas of IberiaPublication . Rábano, Isabel; Gutiérrez-Marco, Juan Carlos; Sá, Artur Abreu; San José, Miguel Angel; Pieren Pidal, Agustin P.; Sarmiento, Graciela Noemi; Piçarra, José Manuel; Durán Valsero, Juan José; Baeza, Eleuterio; Lorenzo, Saturnino
- Caminho de Ferro Mineiro do Lena : desígnio de progresso industrial e socialPublication . Brandão, José Manuel Moraes ValeO caminho de ferreo mineiro de via reduzida, entre a Martingança e Batalha, posteriormente prolongado por Porto de Mós até às minas da Bezerra, apoiou, entre os anos vinte e o final da década de quarenta, a exploração das minas de carvão agrupadas em 1925 no Couto Mineiro do Lena. A fraca qualidade do carvão e o esgotamento dos melhores centros de produção contribuíram, de forma decisiva para o encerramento da linha e posterior abandono da actividade extractiva.