Provenance of Quaternary Sands in the Algarve (Portugal) Revealed by U–Pb Ages of Detrital Zircon

Abstract

The 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 Neoto 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.