Record details

    Calibration of Chitinozoa versus graptolite biozonation in the Wenlock of Builth Wells district (Wales, U.K.), compared with other areas in Avalonia and Baltica
Statement of responsibility
    Jacques Verniers
Other titles
    Studies in Palaeozoic Palynology (Variant.)
    Verniers, Jacques
Source title - serial
    Bollettino della Societa Paleontologica Italiana
    Vol. 38, no. 2-3
    p. 359-380
    4 obr., 2 pl., 3 s.bibl.
    Italské resumé
    Zkr. název ser.: Boll. Soc. paleont. ital.
Subject group
    korelace stratigrafická
    nový taxon
    popis taxonů
    pražská pánev
    zóny biostratigrafické
Geographical name
    Velká Británie-Wales
Abstract (in english)
   The Wenlock sections around Builth Wells, recently used to establish a revised Wenlock graptolite biozonation have been here studied for Chitinozoa. Fifty-five samples have been collected from four sections containing three to five graptolite biozones; samples were taken from the same slabs of rocks used for the redefinition of the graptolite biozonation. The index species of three globally recognized chitinozoa biozones are present, Margachitina margaritana, Cingulochitina cingulata, and Conochitina pachycephala, together with several other characteristic species. These global biozones can be divided into several local biozones. In levels with the centrifugus and murchisoni graptolite biozones, a local margaritana biozone is defined; within the riccartonensis graptolite biozone two biozones are defined, the mamilla and burdinalensis biozones with a third, the tuba biozone at the top.
   The cingulata biozone starts at the base of the dubius graptolite biozone; the pachycephala biozone commences halfway up the rigidus graptolite biozone and the at the base of the (newly defined) lundgreni graptolite biozone, is the subcyatha biozone. Halfway through the lundgreni graptolite biozone the cribrosa biozone begins and continues into the uppermost samples which are referred to the nassa-lundensis graptolite biozones. In five areas of Avalonia and baltica a calibration between chitinozoa and graptolite biozonations has been established for the Wenlock: Builth Wells district (U.K.), Brabant Massif (Belgium), Estonia and northern Latvia, Gotland (Sweden) and mainland Sweden. For the chitinozoa a similar succession of nine biozones and two interzones (as the expression of extinction events) is present in the least three of the five areas. From bottom to top: the Wenlock part of the local margaritana biozones coincides with the centrifugus and murchisoni graptolite biozones.
   The mamilla and burdinnalensis biozones are present respectively in the lower and upper part of the riccartonensis graptolite biozone
    Česká geologická služba
Contributor code
    ČGS (UNM)
Source format
Entered date
    28. 3. 2008
Import date
    8. 8. 2012