User:RYNO FIVE/Trezona Formation

Overview
The Trezona formation dates back to the Cryogenian period which was about 720 - 635 million years ago. The Trezona formation is made up of deposits which were formed between the end of the Sturtian glaciation which was about 643 million years ago and the start of the Marinoan glaciation which was about 635 million years.

Geographic distribution
The anomaly can be found in Australia, Canada, Namibia and Svalbard. The formation found in Southern Australia is made up of out carbonate shelf and slope material. Mainly made up lower marl and cemented carbonate mudstone along with limestone mud clasts and algal flake storm beds. The clasts are passed upwards to oolite shoals and microbial bioherms. The formation at is maximum is about 450 meters thick.

Carbon isotopes
Throughout the studied formations there are different δ13C values. At the base of the formation the δ13C is found to be +8‰ which is after the Sturtian glaciation. Then before the Marionoan glaciation the δ13C has a shift to -18‰. The large negative spike is called the “Trezona anomaly” which was named after the formation in South Australia. This anomaly is also found in China where the δ13C shift had values of +4‰ to -12‰.

Proposed mechanisms
Some reasons for this large negative δ13C anomalies is due to a large increase of nutrients being introduced after the end of the Sturtian glaciation. This increased primary productivity which allowed for an explosion of life. At this time it was found that eukaryotes became the most prominent primary producers. The large negative δ13C is found to be caused by changes in dissolved inorganic carbon in the sea water, diagenetic alteration, and local controls.