A reconnaissance study of Bathonian to Oxfordian (Jurassic) dinoflagellates and acritarchs from the Zaragoza region (NE Spain) and Figueira da Fox (Portugal).

• M. Smelror ^[2] ; Nils Arhus ^[2] ; G. Meléndez ^[1] ; M.D. Lardies ^[1]
  1. [1] Universidad de Zaragoza

     Universidad de Zaragoza

     Zaragoza, España

     
  2. [2] Continental Shelf and Petroleum technology Research Institute Ltd. , Trondheim, Norway
• Localización: Revista española de micropaleontología, ISSN 0556-655X, Vol. 23, Nº. 2, 1991, págs. 47-82
• Idioma: inglés
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• Resumen

  • Marine microfloras of Bathonian to Oxfordian age are recorded from localities at Aguilón, Ricla and Tosos (Zaragoza Region) in northeastern Iberian Chain, Spain, and from Cape Mondego (Figueira da Foz) in central-western Portugal. Abundance, diversity and preservation of the palynomorphs vary considerably; the intervals and sections yielding the richest marine microfloras being the Early Callovian at Agiolón, Bathonian - Early Callovian and Middle-Late Oxfordian at Tosos, and the earliest Callovian at Cape Mondego.

    Characteristic and most prominent among the Late Bathonian - Early Callovian assemblages are representatives of the Dichadogonyaulax sellwoodii group, Sentusidinium spp., Meiourogonyaulax spp., and chorote dinoflagellate cysts assigned to the genera Adnatosphaeridium and Systematophora. Characteristic species restricted to the Oxfordian interval include: Cribroperidinium granuligerum, Epiplosphaera reticulospinosa, Rhynchodiniopsis cladophora and Sirmiodiniopsis orbis. In contrast with the late Bathonian - Early Callovian assemblages, no predominant taxa are observed in the Oxfordian assemblages.

    Only a few of the recorded species are biostratigraphically significant markers. However, the following events might prove to be of biostratigraphic importance:- The earliest appearance of Stephanelytron spp. in the earliest Callovian Bullatus subzone, - the numerical reduction of the Dichadogonyaulax sellwoodii group in the Early Callovian, - the earliest appearance of Cribroperidinium granuligerum in the Upper Oxfordian Bifucatus Zone, - and the extinction of Ctenidodinium ornatum in the Planula Zone.

    The Bathonian to Oxfordian dinoflagellate cyst and acritarch assemblages from the Iberian Peninsula are compared with those recorded from contemporaneous deposits elsewhere in the Circum-Mediterranian region and in central Europe (i.e. areas confined to the Tethyan Realm). The late Bathonian - Early Callovian assemblages are closely related to those described from Israel and northeast Libya. Comparisons of the Oxfordian assemblages suffer from the lack of data, but in general the Iberian microfloras are less diverse and poorer than those known from northwestern and central Europe.