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  • Provenance of detrital zirc...
    Vilar de Oliveira, Camila; Moura, CandidoA.V.

    Journal of South American earth sciences, March 2019, 2019-03-00, Letnik: 90
    Journal Article

    This is the first work focusing on the provenance of Middle Devonian-Early Carboniferous sandstones in the eastern margin of the Parnaíba basin. This sedimentary succession represents the main petroleum system in this basin and is composed, from base to top, of the Itaim, Pimenteiras, Cabeças, Longá and Poti Formations of the Canindé Group. The internal textures and UPb analyses of detrital zircons allowed defining potential source areas for the sediments of this group. A global tendency of sea level rise in the Middle Devonian, in the evolutionary context of West Gondwana, resulted in the establishment of epicontinental seas and deposition of transgressive sedimentary sequences. Shales and sandstones of the Pimenteiras Formation represent extensive records of these Devonian seas on this paleocontinent. This succession provides zircon ages from 3443 to 438 Ma. Detrital zircons with ages of 538–486 Ma are the most abundant, suggesting derivation mainly from nearby younger sources in the Southern subprovince of the Borborema or Tocantins provinces. The transition between the Middle Devonian and Mississippian Periods is marked by progressive retreat of epicontinental seas with minor marine incursions (represented by the Longá Formation) and resulted in the continental deposits of the Cabeças and Poti Formations. Paleocurrent patterns in both formations suggest direct derivation from the Borborema province. The Cabeças, Longá and Poti Formations contain numerous zircons with ages ranging from 999 to 722 Ma. This detrital population indicates derivation from rocks formed during the Cariris Velhos event in the central portion of the Borborema province. The Cabeças Formation also provided an extensive number of zircons with ages ranging from 2034 to 1830 Ma. Further, the studied geologic units, except for the Pimenteiras formation, show detrital contingents with ages of 1.0–1.2 Ga, also suggesting provenance from distal areas. However, as the spectrum of zircon ages of the Canindé Group is similar to that of the Brasiliano belts surrounding the Parnaíba basin, these belts may also be considered candidates to provide sediments for the Middle Devonian-Early Carboniferous deposits. •The Brasiliano belts of southern Borborema subprovince, may be considered the mainly candidate to provide sediments for the Middle Devonian-Early Carboniferous deposits.•Pimenteiras Formation display a essentially unimodal pattern, suggesting derivation also from Brasilia belt or reworking of the cratonic basins of the São Francisco craton.•Did the Cariris-Velhos event exclusively contribute to the Stenian-Tonian zircon age spectra found in the Parnaíba basin?