Changes in weathering, elemental cycling, bioproductivity and redox-conditions of shallow to deep marine environments during the Great Oxidation Episode

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This project seeks to investigate feedback loops between modes and changes in continental weathering, elemental cycling from source to sink, bioproductivity and redox conditions of shallow to deep marine environments in response to the atmospheric oxygen build-up during the Great Oxidation Episode (GOE). The Pretoria Group of the Transvaal Basin in South Africa is an ideal archive for this study with an almost continuous sedimentary record of the GOE from the 2.32 Ga Timeball Hill Formation – which recently revealed repeated short-term cycling between slightly oxidized and reducing atmospheric conditions via changes between mass-dependent and mass independent fractionation of S isotopes (MDF-S and MIF-S, respectively) – up to the c. 2.08 Ga Magaliesberg Formation – which was deposited during the positive δ13Ccarb excursion of the Lomagundi Event, which has previously been interpreted as a time of oxygen overshoot to near-present O2 levels. Geochemical tools that will be used to retrieve this information are major- and trace element systematics combined with TOC, TN, TS and δ13Corg, δ13Ccarb as well as Fe-Mo-W stable isotope measurements. The project is planned for the duration of 36 months.