A transient peak in marine sulfate after the 635-Ma snowball Earth.

Peng, Yongbo; Bao, Huiming; Jiang, Ganqing; Crockford, Peter; Feng, Dong; Xiao, Shuhai; Kaufman, Alan Jay; Wang, Jiasheng · Proc Natl Acad Sci U S A · 2022

basic_science · Level V

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Abstract

SignificanceEarth system's response to major perturbations is of paramount interest. On the basis of multiple isotope compositions for pyrite, carbonate-associated sulfate, carbonates, and organics within, we inferred that the much-debated, enigmatic, extremely <sup>13</sup>C-depleted calcite cements in the ∼635-Ma cap carbonates in South China preserve geochemical evidence for marine microbial sulfate reduction coupled to anaerobic oxidation of methane. This interpretation implies the existence of a brief interval of modern-level marine sulfate. We determined that this interval coincides with the earliest Ediacaran <sup>17</sup>O-depletion episode, and both likely occurred within ∼50 ky since the onset of the 635-Ma meltdown, revealing an astonishing pace of transformation of the Earth system in the aftermath of Earth's latest snowball glaciation.