Rethinking Deep Time Sulfur Isotope Records: Insights from the Paleoproterozoic Onega (Russia) and Francevillian (Gabon) Basins

The archetypal Lomagundi Jatuli Event (LJE) bearing Paleoproterozoic successions from Russia and Gabon are typified by a sequences of ¹³C-enriched shallow-water carbonates, followed by black shales that carry unusually negative organic carbon (δ¹³C_org of ~ -45‰) and positive pyrite sulfur (δ³⁴S > +20‰) isotopic compositions. The opposing behavior of the δ¹³C_org and pyrite δ³⁴S records has been explained by decreasing seawater sulfate concentrations that allowed for enhanced methane cycling in the water column. However, recent sedimentological assessment of the relationship between facies and geochemical profiles challenges the popular opinion that the LJE archives global disturbances in elemental cycles and emphasizes placing stable isotope data into the sedimentological context.

Contact Yuanyuan Liang for Zoom details.