Australia: The Land Where Time Began

A biography of the Australian continent 

Cryogenian Glaciation - Onset of Carbon-Isotope Decoupling

It has been found that throughout the history of the Earth perturbations in the global carbon cycle are often linked to changing palaeogeography, glaciations and biological innovation. During the Ediacaran Period, 635-542 Ma, a pronounced carbonate carbon-isotope excursion was accompanied by invariant or decoupled organic carbon-isotope values, has been explained by a model that relies on a large organic carbon oceanic reservoir. In this paper the authors¹ present carbon-isotope data from carbonate and organic matter demonstrating there was no decoupling between about 820-760 Ma and between the Sturtian and Marinoan glacial events of the Cryogenian Period, about 720-635 Ma there was complete decoupling. The authors¹ suggest that organic carbon pool growth may be related to deep-ocean conditions, iron-rich and sulphate-poor, that is facilitated by an increased Fe:S ratio as a result of the flux of riverine water following the removal of a long-lived continental regolith by the Sturtian Glaciation.

Sources & Further reading

1. Swanson-Hysell, Nicholas L., Catherine V. Rose, Claire C. Calmet, Galen P. Halverson, Matthew T. Hurtgen, and Adam C. Maloof. "Cryogenian Glaciation and the Onset of Carbon-Isotope Decoupling." Science 328, no. 5978 (April 30, 2010 2010): 608-11.