Conodont biozonation in the upper Arenig of Sweden

Conodont faunas from the Arenigian Lanna/Volkhov Stage in Baltoscandia have been the subject of intensive study, particularly during the last decade, and different biozonations based on them have been proposed. The application of some of these zones is discussed here. The present investigation is mainly based on 64 samples from ten sections in Sweden, but conodont collections from Bornholm (Denmark) and Tamsalu (Estonia) have also been studied. Lindström's (1971) concept of the upper Arenigian Microzarkodina parva Zone is essentially replaced by a revised Baltoniodus norrlandicus Zone. The zone corresponds closely to Bagnoli & Stouge's (1997) recently distinguished B. norrlandicus and Lenodus antivariabilis zones, which can be recognized in sections where a more detailed subdivision and correlation is possible under the names of the T. quadrangulum Subzone and the L. antivariabilis Subzone, respectively.