U-Pb detrital zircon ages in synorogenic deposits of the NW Iberian Massif (Variscan belt)

interplay of Devonian-Carboniferous sedimentation and thrust tectonics

José R. Martínez Catalán*, Javier Fernández-Suárez, Carlos Meireles, Emilio González Clavijo, Elena Belousova, Ayesha Saeed

*Corresponding author for this work

    Research output: Contribution to journalArticle

    41 Citations (Scopus)

    Abstract

    Detrital zircons from Devonian and Carboniferous synorogenic flysch deposits occurring in an imbricate stack have been dated by laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS) to: (1) obtain a maximum depositional age to constrain the maximum age limit for thrusting of exotic terranes in the NW Iberian Massif; (2) correlate the zircon age populations with published ages in nearby units to establish their possible source areas. The maximum depositional ages are Late Devonian for rocks high in the structural nappe pile (Gimonde Formation), in accordance with palynomorph dating, and around the Devonian-Carboniferous boundary for structurally lower samples (San Vitero Formation). Used in conjunction with previously published ages, the new ages are interpreted in terms of the advance of the thrust system responsible for the emplacement of exotic terranes upon the Iberian autochthon during the Variscan collision. Early Variscan zircon population ages indicate the exotic terranes as the source of synorogenic, sediments, whereas their scarcity suggests derivation from the Iberian autochthon. One of the samples analysed lacks Variscan detrital zircons; this feature, together with the absence of an Early Palaeozoic zircon age population, puts into question its synorogenic character and suggests that the sample may be representative of the preorogenic parautochthon.

    Original languageEnglish
    Pages (from-to)687-698
    Number of pages12
    JournalJournal of the Geological Society
    Volume165
    Issue number3
    DOIs
    Publication statusPublished - May 2008

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