Résumé
•Presents the highest resolution dataset of a BIF known to date.•Investigates local and global controls on the preservation of redox proxies.•Iron speciation through the Boolgeeda IF and overlying Kungarra Formation.•Shallow marine oxic conditions contemporary with Boolgeeda IF deposition (2.45 Ga).
The Boolgeeda Iron Formation and overlying Turee Creek Group, Hamersley Basin, Western Australia, represent a conformable succession of sediment deposited between 2.45 and 2.22 Ga. This interval of geologic history is of significant interest because it spans the Great Oxidation Event (GOE), when oxygen first accumulated in Earth’s atmosphere. Here we present geochemical and petrographic data from the uppermost 45 m of the Boolgeeda Iron Formation and an additional 30 m of the overlying Kungarra Formation mudstones, as sampled from the Turee Creek Drilling Project 1 drill core (TCDP1). This core captures the termination of BIF deposition in the Hamersley Basin and coincides with a global decline in BIF deposition in the Paleoproterozoic. We provide a continuous, high resolution chemostratigraphic dataset of major and trace element concentrations, as well as Fe speciation data, to assess the relationship between the rise of atmospheric oxygen and the subsequent decline in BIF deposition. We also highlight the interplay between local and global controls on the preservation of redox signatures, including the rise and fall of local base-level, input of weathered continental material, influx of reduced sulfur species associated with the continental weathering, and global increases in atmospheric oxygen. We interpret Boolgeeda deposition to have taken place under shallow water, oxic conditions overlying anoxic ferruginous deep water. Intermittent periods of oxidative weathering led to influxes of redox sensitive trace elements from land as continental sulfide minerals were weathered. This also led to the temporary disappearance of MIF-S, but O2 remained below the threshold capable of completely eliminating S isotope signatures associated with the MIF-S recycling.