Journal of

GEOsciences

  (Formerly Journal of the Czech Geological Society)

Original Paper

Radek Mikuláš

Trace fossils at the Arenig - Llanvirn boundary (Ordovician, Czech Republic)

Journal of the Czech Geological Society, volume 39 (1994), issue 2-3, 205 - 212

Changes of ichnological content at the Klabava Fm./Šárka Fm. boundary (= near the Arenig/Llanvirn boundary) consist namely in decrease of diversity of ichnotaxa and in diminution of ichnofabric indices, joined with volcanic activity and consequent sedimentation of Fe-oolites. Trace fossil assemblages in clay shales of uppermost part of Klabava Formation, compared with those from lower part of Šárka Fm., do not differ much both in ethological spectrum of traces and in occurrence of identical or similar ichnotaxa. Overall intensity of bioturbation (ichnofabric index) is somewhat smaller in lower part of Šárka Fm. than in uppermost layers of Klabava Fm. Ichnotaxa Chondrites div. ichnosp., Planolites ichnosp., Glockerichnus glockeri, Phycodes ichnosp., Helminthopsis ichnosp., Rhizocorallium ichnosp., ?Zoophycos ichnosp., a.o., are represented in these ichnoassemblages.