Editing Archean Eon (section)

=== Sulfur Isotopes (Sulfur-32, Sulfur-33, Sulfur-34, and Sulfur-36) ===

* Variations in sulfur isotopes, especially the anomalies in sulfur-33 (³³S), are critical for understanding the redox state of the Archean atmosphere and oceans. These anomalies are unique to the Archean and suggest a lack of atmospheric oxygen, allowing for the preservation of mass-independent fractionation signals in sulfur isotopes, which would not occur in an oxygen-rich atmosphere.
* The ratios of sulfur isotopes can also indicate the presence and nature of microbial sulfur cycling processes, such as sulfate reduction, which plays a significant role in the sulfur cycle.