Title: Sulfate triple-oxygen-isotope evidence confirming oceanic oxygenation 570 million years ago
Author: Haiyang Wang, Yongbo Peng*, Chao Li*, Xiaobin Cao, Meng Cheng, Huiming Bao
Journal: Nature Communications
Year of Publication: 2023
Volume: 14
DOI: 10.1038/s41467-023-39962-9
Abstract：The largest negative inorganic carbon isotope excursion in Earth's history, namely the Ediacaran Shuram Excursion (SE), closely followed by early animal radiation, has been widely interpreted as a consequence of oceanic oxidation. However, the primary nature of the signature, source of oxidants, and tempo of the event remain contested. Here, we show that carbonate-associated sulfate (CAS) from three different paleocontinents all have conspicuous negative 17O anomalies (Δ17OCAS values down to -0.53‰) during the SE. Furthermore, the Δ17OCAS varies in correlation with its corresponding δ34SCAS and δ18OCAS as well as the carbonate δ13Ccarb, decreasing initially followed by a recovery over the ~7-Myr SE duration. In a box-model examination, we argue for a period of sustained water-column ventilation and consequently enhanced sulfur oxidation in the SE ocean. Our findings reveal a direct involvement of mass-anomalously 17O-depleted atmospheric O2 in marine sulfate formation and thus a primary global oceanic oxygenation event during the SE.
Key Words: CARBONATE-ASSOCIATED SULFATE; SULFUR ISOTOPES; ATMOSPHERIC OXYGEN; OXIDATION; PYRITE; INSIGHTS; ORIGIN; CYCLE; CONSTRAINTS; DISSOLUTION
