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 applicatio n of some of these zones is discussed here. The present investigation is ma inly based on 64 samples from ten sections in Sweden, but conodont collecti ons from Bornholm (Denmark) and Tamsalu (Estonia) have also been studied. L indstrom's (1971) concept of the upper Arenigian Microzarkodina parva Zone is essentially replaced by a revised Baltoniodus norrlandicus Zone. The zon e corresponds closely to Bagnoli & Stouge's (1997) recently distinguished B . norrlandicus and Lenodus antivariabilis zones, which can be recognized in section's where a more detailed subdivision and correlation is possible un der the names of the T. quadrangulum Subzone and the L. antivariabilis Subz one, respectively.