Loading...
6 results
Search Results
Now showing 1 - 6 of 6
- Idades U-Pb de zircões nas areias quaternárias do AlgarvePublication . Veiga-Pires, C.; Moura, Delminda; Rodrigues, Bruno; Machado, Nuno; Campo, Leif; Simonetti, AntonyO objectivo deste trabalho é realçar e quantificar a contribuição das variações geomorfológicas nas modificações da rede de drenagem através de datações de minerais detríticos que permitam a caracterização de fontes de sedimentos desde o Pliocénico.
- Caracterização da evolução do perfil longitudinal das ribeiras do oeste do Algarve - dados preliminaresPublication . Rodrigues, Bruno; Veiga-Pires, C.; Moura, Delminda; Fernandes, Paulo; Boski, T.A actual rede hidrográfica na região do Algarve, devido à proximidade do mar e ao seu contexto tectónico, teve ao longo da sua formação uma forte influência dos efeitos eustáticos, tendo também o clima regional um papel fulcral na incisão do vales actuais a diferentes escalas temporais.
- Variability of detrital zircons from beaches and rivers in the western Algarve Region-South PortugalPublication . Rodrigues, Bruno; Moura, Delminda; Machado, Nuno; Veiga-Pires, C.Zircon is a common accessory mineral in most rocks and sediments, and although it is ubiquitous, it possesses a considerable petrologic interest. In the scope of CHYNA project, some samples of detrital sediments have been collected in rivers and beaches from Western Algarve region. The present work presents the results of the analyses undergone with the intent to document the existing zircons’ variability in these samples. The zircons from 22 samples have been analysed based on their shape, colour and inclusions. There is predominance of rounded and subrounded grains, generally colourless and without inclusions. Systematic differences between beaches and rivers are not observed, indicating that both environments have the same zircon sources.
- Provenance of Quaternary sands in the Algarve (Portugal) revealed by U-Pb ages of detrital zirconPublication . Veiga-Pires, C.; Moura, Delminda; Rodrigues, Bruno; Machado, Nuno; Campo, Leif; Simonetti, AntonyThe application of U–Pb dating by laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) to determine the sources of detrital zircon in Neogene and Quaternary sands of the Algarve (southern Portugal) revealed the presence of three age groups: Palaeozoic to Neoproterozoic (200–800 Ma), Palaeoproterozoic (ca. 1700–2100 Ma) and Neo- to Meso-Archaean (2600–3200 Ma). The results suggest that at least some of the detrital grains were derived from pre-existing formations from the Southern Portuguese Zone of the Variscan orogen (namely Palaeozoic metasediments) and Mesozoic sedimentary rocks. The older sources from which zircons probably derived originally seem to be metamorphic rocks cropping out northeast of the Southern Portuguese Zone. Previous work shows that these older rocks from the Variscan Ossa–Morena and Central Iberian Zones contain inherited zircons with the same ages as those obtained in the present study from sediments. In parallel, the results also show a consistency in the source ages of the detrital zircons from Lower Pliocene to Holocene sediments, thus contributing to the discussion of known changes to the river drainage network in the Algarve region during the Pliocene based on published field observations.
- Variabilidade dos Zircões de ribeiras e praias do Algarve Ocidental - dados preliminaresPublication . Rodrigues, Bruno; Moura, Delminda; Machado, Nuno; Veiga-Pires, C.O Zircão é um mineral acessório comum na maioria das rochas, possuindo um considerável interesse petrológico por ser extremamente resistente à meteorização química e de amplo uso em estudos radiométricos (Heimlich et al., 1975). Devido à sua extrema resistência à meteorização e ao transporte, o zircão possui um carácter ubíquo nos sedimentos.
- Visualization of geomorphological features through GIS. The study case of MonchiquePublication . Rodrigues, Bruno; Boski, T.; Moura, Delminda; Veiga-Pires, C.Foram identificados na Serra de Monchique, vestígios de superfícies de erosão a diferentes altitudes.