Browsing by Author "Simonetti, Antony"
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- 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.
- 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.
- U-Pb zircon ages and provenance of Quaternary sands: first results for Algarve (Portugal)Publication . Veiga-Pires, C.; Moura, Delminda; Campo, Leif; Simonetti, Antony; Machado, NunoThe mineralogical composition of beach sands results from several factors the most important of which are the composition of the source rocks and mixing by coastal processes. Since the pioneering work of Trask (1952) who used augite as a mineral tracer, the study of the heavy mineral assemblage of beach sands have been used to determine sediment sources and to characterize sediment transport and mixing. This is important not only to reconstruct the evolution of hydrographic networks but also to help in understanding ongoing and evolving coastal processes.