Iron Isotope Characteristics of Hot Springs at Chocolate Pots, Yellowstone National Park

Research at Chocolate Pots Hot Springs in Yellowstone National Park reveals that iron isotope fractionation in hydrothermal systems is influenced by silica and microbial processes. The study found that Fe(III) oxides formed through atmospheric oxidation exhibit higher ⁵⁶Fe/⁵⁴Fe ratios compared to aqueous Fe(II), but the degree of fractionation is less than predicted for a closed system at isotopic equilibrium. This suggests that light iron isotopes may sorb onto Fe(III) oxide surfaces in the presence of silica or regenerate via microbial reduction deeper within the system. These findings imply that silica plays a significant role in governing iron isotope fractionation, with potential implications for understanding such processes under low-oxygen conditions, such as those on early Earth or Mars.

Wu, L., Brucker, R. P., Beard, B. L., Roden, E. E., & Johnson, C. M. (2013). Iron Isotope Characteristics of Hot Springs at Chocolate Pots, Yellowstone National Park. Astrobiology, 13(11), 1091–1101. https://doi.org/10.1089/ast.2013.0996