An opportunistic trace fossil assemblage from the flysch of the Inoceramian beds (Campanian-Palaeocene), Bystrica Zone of the Magura Nappe, Carpathians, Poland

Abstract

A relatively poorly diversified trace fossil assemblage from thin- and medium-bedded flysch of the Inoceramian beds in the Polish Outer Carpathians is dominated by postdepositional r-selected Chondrites, Planolites and Helminthoida. Predepositional K-selected forms are very rare. This, together with a lack of evidence for bottom erosion and the relatively dark colour of interbedded mudstone and siltstone, suggest that low sediment oxygenation was the main factor controlling benthic life. Preservational factors, related to the fluid consistency of sediment and to mixed layers, seem to be present, but subordinate. Small-scale changes of diversity and abundance of the trace fossils within the sections probably reflect changes in sediment oxygenation.