Table 3. Classification of Depositional Paleoenvironments According to the Redox Condition.
| zone | redox conditions | [Fe]/[S] | Pr/Ph | DBT/Phen |
|---|---|---|---|---|
| 1A, 1B | anoxic/sulfidica | [Fe] < [S] | <1 | >1 |
| 2 | anoxic/fermentative | [Fe] > [S] | <1 | <1 |
| 1A, 1B, 2 | anoxic/hypersaline | variable | <0.4 | variable |
| 3 | anoxic/nonsulfidica | [Fe] > [S] | 1–3 | <1 |
| 4 | periodically oxic or dysoxic | [Fe] ≫ [S] | >3 | <1 |
a
The term sulfidic refers to conditions where free H2Sn species are present. [Fe] represents the concentration of iron capable of reacting with reduced sulfur to form iron sulfides. [S] represents the concentration of reduced sulfur capable of reacting with iron to form iron sulfides. Adapted from Hughes et al.10