Australia: The Land Where Time Began

A biography of the Australian continent 

Photic Zone Euxinia - Their role in Exceptional Preservation of Fossils Revealed by Biomarkers: An Organic Chemical Perspective

According to the authors¹ is has been shown that for elucidating biochemical changes occurring during oceanic anoxic events, including mass extinction and conditions in which unique fossil preservation occurs, Photic Zone Euxinia (PZE ) is important. An invertebrate fossil, that included well-preserved soft tissues, from the Gogo Formation, Western Australia (Canning Basin) dated to 380 Ma, was subjected to organic chemical analysis, the results showing biomarkers and carbon isotope values that are consistent with PZE, as well as a consortium of sulphate-reducing bacteria, which result in exceptional preservation of the fossil and biomarkers. Phytoplankton, green sulphur bacteria (Chlorobi), and sulphate-reducing bacteria biomarkers, with the concentration increasing towards the nucleus where the fossil was preserved, were contained in the concretion of carbonate. The fossil is suggested to be a crustacean by the spatial distribution of cholestane which is unequivocally associated the fossilised tissue and its high abundance relative to total steranes. The authors¹ suggest that a pivotal role in the preservation of soft tissue from the fossil and its associated low-maturity biomarker ratio is played by the presence in the Devonian system of an active sulphur cycle, that included the reduction of sulphate and the PZE that resulted.

Sources & Further reading

1. Melendez, Ines, Kliti Grice, Kate Trinajstic, Mojgan Ladjavardi, Paul Greenwood, and Katharine Thompson. "Biomarkers Reveal the Role of Photic Zone Euxinia in Exceptional Fossil Preservation: An Organic Geochemical Perspective." Geology 41, no. 2 (February 1, 2013 2013): 123-26.