http://hdl.handle.net/10316/24587 2020-03-07T13:45:23Z 2020-03-07T13:45:23Z Borges, Leonor Calvão Silva, Ana Margarida Dias da Vivas, Diogo Freitas, Cristiana http://hdl.handle.net/10316/88154 2019-11-21T21:39:27Z 2019-10-01T00:00:00Z

Title: A difusão on-line da coleção do Cónego Isaías da Rosa Pereira do Instituto de Paleografia da Faculdade de Letras da Universidade de Coimbra: proposta no âmbito da web 2.0 Authors: Borges, Leonor Calvão; Silva, Ana Margarida Dias da; Vivas, Diogo; Freitas, Cristiana Abstract: O Instituto de Paleografia da Faculdade de Letras da Universidade de Coimbra foi criado em 1974 pelo Prof. Doutor Cónego Avelino Jesus da Costa, que o dirigiu até 1978, com o objetivo de dotar os alunos de paleografia e diplomática de coleções de reproduções de documentos (ou mesmo originais), imprescindíveis para o seu estudo, bem como de uma biblioteca especializado de apoio. Em 1991, o Prof. Doutor Cónego Isaías da Rosa Pereira, professor das disciplinas de paleografia e diplomática na Faculdade de Letras da Universidade de Lisboa, e detentor de uma coleção de 60 documentos (pergaminho e papel) datados entre 1491 e 1888, de diversas tipologias e diferentes proveniências, fez dela uma doação ao Instituto de Paleografia para benefício de professores e estudantes. O objetivo desta comunicação é assim dar a conhecer esta importante coleção documental e apresentar um projeto de difusão digital dos seus conteúdos e saberes paleográficos tão importantes para a memória patrimonial, aproveitando os recursos da web 2.0. Partindo de uma análise de projetos similares, apresenta-se um modelo de divulgação de conteúdos didáticos para o ensino e estudo da paleografia, permitindo uma maior visibilidade das coleções junto de um maior número de utilizadores. Conclui-se que conseguir envolver o público é uma forma de retirar as instituições de memória da sombra, mostrando-as como centros de cultura e memória patrimonial, promovendo, ao mesmo tempo, o aumento do número de utilizadores e a valorização das coleções.

2019-10-01T00:00:00Z Reis, Anabela Parker, Andrew Alencoão, Ana http://hdl.handle.net/10316/27461 2019-05-28T23:51:00Z 2014-05-01T00:00:00Z

Title: Storage and origin of metals in active stream sediments from mountainous rivers: a case study in the River Douro basin (North Portugal) Authors: Reis, Anabela; Parker, Andrew; Alencoão, Ana Abstract: The study area is located in the transboundary River Douro basin (northern Portugal); it comprises the River Corgo fluvial network, which drains a meso-scale rural catchment with an area of 295 km2, underlain by crystalline rocks, in a temperate climate. The results reported in this study derive from a geochemical survey of active fluvial sediments, with the aim of characterising the spatial and temporal distribution of the contents of As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn in a basin with mountainous features. To assess total contents of metals and their potential availability, as well as possible different origins of metals (natural vs. anthropogenic), a sequential chemical approach was used (modified BCR procedure). Multivariate data analysis (PCA) was used to assist the interpretation of datasets. The results show that, on the one hand, the metal contents distribute among all the geochemical phases studied. For the most relative labile fractions the reducible fraction is the most significant. The element-partitioning among geochemical phases indicates: (a) Co and Mn are transported in greater proportions in the most labile fraction, as exchangeable ions, as well as important proportions of Ni, Zn and Cu; (b) Cd and Pb associate preferentially with the hydroxides of Fe and Mn; (c) Cr and Cu are also transported by the organic phase; (d) the residual phase transport important proportions of Cr, Ni, Zn, Cu, Fe and Pb. The higher concentrations of Cu, Zn and, in particular, Pb, in the most labile fractions, which are higher where the total contents are also higher (and not concomitant with a correspondent increase in the residual fraction), suggest an important contribution of anthropogenic activities to the total contents of these elements in the sediments. Chromium and Ni are the main metals from a lithological source, with relatively higher contents in the residual fraction, and the lowest in the most mobile fractions. On the other hand, the spatial distribution pattern of metal contents in the mobile and semi-mobile fractions (available + reducible + oxidisable), shows that, in general, higher contents of metals in the most mobile fractions occur along the main courses of the major tributaries, in particular in the flatter reaches. The patterns of seasonal occurrence and distribution of metals show, in general, that the relative contents associated with the potentially available fraction increase during the period of low flow, which extends from April to September.

2014-05-01T00:00:00Z Sommer, Carlos Augusto Lima, Evandro Fernandes Machado, Adriane Rossetti, Lucas de Magalhães May Pierosan, Ronaldo http://hdl.handle.net/10316/27453 2019-05-28T23:50:59Z 2013-11-01T00:00:00Z

Title: Recognition and characterisation of high-grade ignimbrites from the Neoproterozoic rhyolitic volcanism in southernmost Brazil Authors: Sommer, Carlos Augusto; Lima, Evandro Fernandes; Machado, Adriane; Rossetti, Lucas de Magalhães May; Pierosan, Ronaldo Abstract: Neoproterozoic magmatism in southern Brazil is associated with translithospheric shear belts and strike-slip basins in a post-collisional setting related to the last stages of the Brasilian-Pan African Orogenic Cycle. It evolved from an association of high-K calc-alkaline, leucocratic-peraluminous and continental tholeiitic magmas, to an association with shoshonitic magmas and, eventually, to an association with magmas of the sodic mildly alkaline series. This magmatism varies from metaluminous to peralkaline and exhibits alkaline sodic affinity. A large volcanism is related to this alkaline sodic magmatism and is named the Acampamento Velho Formation. This unit was coeval with subaerial siliciclastic sedimentation in post-collisional basins preserved in the region. The Acampamento Velho Formation consists of pyroclastic and effusive volcanic deposits, which are mainly silicic, emplaced under subaerial conditions. The best exposures of this volcanism occur on the Ramada and Taquarembó plateaus, located southwest of Rio Grande do Sul in southernmost Brazil. The pyroclastic flow deposits are composed mainly of juvenile fragments such as pumices, shards and crystal fragments. Welding is very effective in these units. High-grade ignimbrites occur at the base and intermediate portions of the deposits and rheoignimbrites are observed at the top. The pre-eruptive temperature calculations, which were obtained at the saturation of zircon, revealed values between 870 °C and 978 °C for Taquarembó Plateau and 850 °C–946 °C for Ramada Plateau. The calculated viscosity values vary from 6.946 to 8.453 log η (Pas) for the rheoignimbrites and 7.818 to 10.588 log η (Pas) for the ignimbrites. Zr contents increase toward the top of the pyroclastic sequence, which indicates an increase in peralkalinity and determines the reduction in viscosity for clasts at the upper portions of the flows. The patterns of the structures of the ignimbrites and rheoignimbrites in the Taquarembó and Ramada plateaus accords well with successive pyroclastic flows that halts en masse. In this model the entire pyroclastic flow halts en masse, so complex vertical changes in grain size and composition are interpreted as recording deposition from successive discrete pyroclastic flows. The stratification observed in intermediate units in Taquarembó Plateau might reflect in this case variation in eruptive dynamics and short pauses.

2013-11-01T00:00:00Z Vaz, David A. Silvestro, Simone http://hdl.handle.net/10316/26839 2019-05-28T23:50:58Z 2014-02-15T00:00:00Z

Title: Mapping and characterization of small-scale aeolian structures on Mars: An example from the MSL landing site in Gale Crater Authors: Vaz, David A.; Silvestro, Simone Abstract: A new set of methodologies, which allow a simple and fast mapping and characterization of small-scale aeolian structures on Mars is introduced in this work. We follow an object-based approach in which the bedform crestlines are automatically mapped and characterized. From the methodology validation, we conclude that the quality of the obtained results is comparable with human-produced photointerpretations. We show that the accuracy associated with the measurement of mean trends from the automatically mapped patterns is less than 10°. Through the analysis of two areas located near the MSL landing site in Gale Crater, we explore some of the possibilities that the automatic mapping technique enables. Namely, for multitemporal surveys and ripple pattern analysis. We demonstrate how the mapped ripple patterns can be used to assess local wind orientations, and we analyze some examples that illustrate the diversity of wavelength spatial distributions that can be found on Mars. We try to relate these pattern wavelength variations with the possible local influence of granulometry and wind shear velocity.

2014-02-15T00:00:00Z