Australia: The Land Where Time Began

A biography of the Australian continent 

Ediacara Member, Rawnsley Quartzite, South Australia, Depositional and Preservational Environments – Assessment of palaeoenvironmental Proxies and Timing of ‘Ferruginisation’

The palaeoenvironmental setting of the Ediacaran biota is preserved in the eponymous Ediacaran Member of the Rawnsley Quartzite, South Australia has been a longstanding subject of debate. There are a number of suggested interpretations such as deep marine, shelfal, intertidal and terrestrial. In this paper Tarhan et al. present the results of an examination of the evidence supporting and against various palaeoenvironmental interpretations of the fossiliferous Ediacara Member, and also explore the range of palaeoenvironmental proxies that have been employed in such studies in the past. The importance is emphasised of reconciling palaeoenvironmental analysis with an understanding of the processes of sedimentology and outline which of the proxies are consistent with this approach. It is essential to assess carefully palaeoenvironmental parameters to reconstruct the depositional and early diagenetic history of the Ediacara Biota, and therefore the physical, chemical and biological factors that have influenced the development and fossilisation of these earliest known examples of complex life. The conclusion of Tarhan et al. is that there is no compelling evidence of a terrestrial setting for the Ediacara Member, though there is strong support for a shallow marine depositional environment.

Sources & Further reading

1. Tarhan, L. G., M. L. Droser and J. G. Gehling (2015). "Depositional and preservational environments of the Ediacara Member, Rawnsley Quartzite (South Australia): Assessment of paleoenvironmental proxies and the timing of ‘ferruginization’." Palaeogeography, Palaeoclimatology, Palaeoecology 434(0): 4-13.