A Přídolí–Lochkovian conodont zonation in Sardinia and the Carnic Alps: implications for a global zonation scheme

 

Authors: Corradini C, Corriga MG

Published in: Bulletin of Geosciences, volume 87, issue 4; pages: 635 - 650; Received 26 July 2011; Accepted in revised form 7 February 2011; Online 17 April 2012

Keywords: biostratigraphy, conodont zonation, Přídolí, Lochkovian, Carnic Alps, Sardinia,

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Abstract

The main conodont zonation schemes for the Přídolí and the Lochkovian presents some problems that make difficult their use in several geographical areas. Data from several sections in Sardinia and the Carnic Alps not only allow to built a regional zonation scheme for these areas, but also suggest possible solutions of global validity. In the Carnic Alps and Sardinia, the Přídolí is subdivided into three zones: eosteinhornensis s.l., Lower and Upper detortus. The latter results after the subdivision of the former detortus Zone on the basis of the Last Appearance Datum of some coniform species (Dapsilodus obliquicostatus, Coryssognathus dubius and Panderodus recurvatus) that became extinct almost simultaneously in the latest Přídolí. Daps. obliquicostatus is chosen as the marker, being the most common and easily identifiable species. In the Lochkovian six zones are discriminated: hesperius, carlsi, transitans, eleanorae, trigonicus and pandora β. The hesperius Zone, which includes the postwoschmidti subzone in its upper part, is expanded to include most of the eurekaensis zone of the “global” scheme, because the marker Oz. eurekaensis is not present. The carlsi Zone corresponds to the upper part of the eurekaensis Zone and to the lower part of the former mid-Lochkovian delta Zone (= omoalpha Zone). The rest of the Middle Lochkovian is subdivided into the three zones (transitans, eleanorae and trigonicus) already proposed in Nevada and Spain, followed by the pandora β Zone. All the zones are discussed and checked for their applicability in other palaeogeographical regions.\r\n