Extremely cold ocean temperatures in iron formation brine pools of snowball Earth.

ABSTRACT: For the severe low-latitude "snowball Earth" glaciations, glacial deposits occurring on all continents is well-established. However, cold, salty, ice-covered oceans-a salient prediction of snowball Earth-is difficult to establish geologically. Here we demonstrate that anomalously high iron isotope values (δ⁵⁶Fe) of snowball iron formation-never observed in earlier anoxic Archaean oceans-can be attributed to additional temperature-dependent fractionation in extremely cold brine pools in the snowball ocean. Experiments and modeled fractionations relevant to the precipitation of iron formation demonstrate temperature-dependent δ⁵⁶Fe fractionation, where colder temperatures correspond with more positive δ⁵⁶Fe. Assuming the ~ 0.9‰ differential in δ⁵⁶F

SUBMITTER: Lu K 

PROVIDER: S-EPMC12800124 | biostudies-literature | 2025 Dec

REPOSITORIES: biostudies-literature