Trails from the Vienna woods: Paleoenvironments and trace fossils of cretaceous to eocene flysch, Vienna, Austria

Abstract

Environments of deposition within a submarine slope-fan-basin plain system have been reconstructed for three flysch formations on the basis of sedimentary facies and facies associations. The dominantly arenitic rocks of the Eocene Greifenstein Sandstone were deposited in large channels on the inner fan and the inner part of the middle fan. The pelitic and arenitic strata of the Upper Cretaceous Sievering Formation were deposited in large channels and on interchannel surfaces of the middle fan. The dominantly pelitic rocks of the Paleocene—Eocene Laab Formation were deposited on the outer fan and the outer part of the middle fan. Most of the trace fossils in these formations are characteristics of the Nereites facies, which is typical of deep-water paleoenvironments. Nearly all the abundant full-relief traces in pelites and hyporelief traces on the soles of arenites were constructed by deposit-feeding, inbenthic animals burrowing and feeding in mud. The epirelief traces on the upper surfaces of arenites are surface trails of epibenthic deposit-feeders, scavengers, or carnivores. Abundance and diversity of inbenthic deposit-feeders apparently were limited by sediment grain size, and their traces are abundant only in thinly interbedded, finegrained arenites and pelites deposited in middle fan channel and interchannel environments of the Sievering Formation and parts of the Laab Formation. Abundance of epibenthic animals may have been limited by temporal and geographic continuity of suitable sandy substrates, and their traces are abundant only locally in ungraded, coarser-grained arenites deposited in inner fan channel environments of the Greifenstein Sandstone.