Variability over time in the sources of South Portuguese Zone turbidites: evidence of denudation of different crustal blocks during the assembly of Pangaea

摘要: This study combines geochemical and geochronological data in order to decipher the provenance of Carboniferous turbidites from South Portuguese Zone (SW Iberia). Major trace elements 25 samples graywackes mudstones Mertola (Visean), Mira (Serpukhovian), Brejeira (Moscovian) Formations were analyzed, 363 U-Pb ages obtained on detrital zircons five using LA-ICPMS. The results indicate that turbiditic sedimentation during was marked by variability sources, involving denudation different crustal blocks a break synorogenic volcanism. Visean is characterized accumulation immature (Mertola Formation base Formation) inherited terrane with intermediate mafic source rocks. These rocks probably formed relation Devonian magmatic arcs poorly influenced sedimentary recycling, as indicated almost total absence pre-Devonian typical Gondwana and/or Laurussia basements. presence grains indicates volcanism active at this time. Later, Serpukhovian Moscovian (Mira Formations) included detritus derived felsic mature situated far magmatism. abundance Precambrian Paleozoic reveals strong recycling A peri-Gondwanan zircon populations Neoproterozoic (Cadomian-Avalonian Pan-African zircon-forming events), Paleoproterozoic, Archean ages. late Ordovician Silurian turbidites, which have no correspondence basement SW Iberia, their most probable source.