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Famennian (Late Devonian) conodonts from the Pizzul West section (Carnic Alps, Italy)
No full textConodonts from the Pizzul West section are presented. e section is located in the Cason di Lanza/Mt. Zermula area
of the central Carnic Alps and it exposes about twenty-four metres of Upper Devonian limestone. e forty-one taxa documented
allow the discrimination of seven biozones of Frasnian and Famennian: Upper rhenana, Upper crepida, Uppermost crepida,
Lower rhomboidea, Upper rhomboidea, Lower marginifera and Lower expansa
The Annulata Event at the Pramosio Bassa section.
Full text linkThe Pramosio area was studied by Michele Gortani since the beginning of the 20th century. The Pramosio Bassa section was briefly described by Perri et al. (1998) and Spalletta & Perri (2001). Mossoni (2014) studied magnetic susceptibility, magnetic hysteresis and major elements content of the section. The results of this study fit very well with the palaegeographic position of the Carnic microplate during the Late Devonian hypothesized by Schönlaub (1993) and von Raumer & Stampfli (2008). According to these Authors the Carnic microplate was located far away from land. Mossoni (2014) demonstrated that during the limestone deposition the detrital input was scarce, this is consistent also with the transgressive event considered as triggering cause of the Annulata radiation. All the studied parameters show values consistent with the identification of the Upper Annulata Event in correspondence of the level of sample PB5a (Mossoni 2014). In the Carnic basin a general transgressive tendency from the Lower marginifera Zone to the base of the Lower postera Zone (Palmatolepis marginifera marginifera–Polygnathus styriacus zones of Spalletta et al. 2017) was inferred by Perri & Spalletta (2000) based on conodont biofacies analysis. Hartenfels & Becker (2016) report that the level yielding a mass occurrence of Prionoceras (bed of sample PB5a) can be considered as an equivalent of the Wagnerbank of Thuringia. According to Hartenfels & Becker (2016) the goniatite-rich limestone of the Wagnerbank represents a regressive phase in the highest part of the annulata Zone (UD IV-A)
The Devonian/Carboniferous boundary in Sardinia (Italy)
No full textIn Sardinia (Italy) two sections, located in the southeastern part of the island, expose the Devonian/Carboniferous Boundary: the Monte Taccu Section and the Bruncu Bullai section. Both expose limestones from the middle Famennian to the lower Tournaisian Siphonodella jii Zone. The limestone sequence is interrupted by a thin level of shales representing the Hangenberg Event. Data on conodont biostratigraphy and magnetic susceptibility across the Devonian/Carboniferous Boundary are here summarised and reviewed
Review of conodonts across the Devonian/Carboniferous boundary: implication for the redefinition of the boundary and a proposal for an updated conodont zonation
No full textThe Devonian/Carboniferous boundary definition is under revision because of problems recognized in the last few years in regard to the index taxon and the type section. The distribution of conodont species of Bispathodus, Branmehla, Palmatolepis, Polygnathus, Protognathodus, Pseudopolygnathus, and Siphonodella have been investigated in order to evaluate their stratigraphic potential for the redefinition of the Devonian/Carboniferous boundary and a revised biozonation of the uppermost Famennian and lowermost Tournaisian. For the definition of the boundary it is necessary to find criteria that guarantee stability in the future, and do not significantly change the present stratigraphic position. Only a few conodont species first appear close to the present boundary and most of these do not have the characteristics of a stratigraphic index taxon, since all are quite rare. Only the FAD of Protognathodus kockeli and the FAD Siphonodella bransoni (= S. duplicata M1) can be considered as conodont markers, although both these possible positions for the DCB boundary have advantages and problems. We propose an updated biozonation scheme across the boundary based on the FADs of Bispathodus ac. aculeatus, Bispathodus costatus, Bispathodus ultimus, Protognathodus kockeli, Siphonodella bransoni and Siphonodella duplicata
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