Palaeoenvironments of Eocene Bryzoa, St Vincent Basin, South Australia

Abstract

The diverse facies of the Eocene sediments of the St Vincent Basin, South Australia, contain a wide range of bryozoan faunas, ranging from high to low diversity and abundance assemblages, regarding both taxonomy and growth forms. The basin was probably often restricted from the open ocean by the Kangaroo Island basement high. The initial transgressive marine facies resulted in the greatest diversity and abundance of bryozoans throughout the basin. This is interpreted as a well oxygenated and moderate energy environment. Trends in the bryozoan assemblages include a decrease in 'sand fauna' species up-section (Melicerita, Siphon-icytara and free-living species), and a reduction in species and growth form diversity. Late Eocene assemblages indicate deep water environments, which may be an artefact of the restricted environment. © 2005 Taylor & Francis Group.