Archean-Proterozoic unconformity on the Fennoscandian Shield: Geochemistry and Sr, C and O isotope composition of Paleoproterozoic carbonate-rich regolith from Segozero Lake (Russian Karelia)

The Black Angel deposit, Greenland: a Paleoproterozoic evaporite-related Mississippi Valley-type Zn–Pb deposit

“…The evaporites occur over a thickness of 500 m within an area of more than 2000 km 2 , indicating that a large marine sulfate reservoir developed by ca. 2090 Ma, although it is debated whether it was fully or partially open to the global ocean (e.g., Alfimova et al 2022). The seawater sulfate reservoir is generally considered to collapse in the aftermath of the Lomagundi Event when redox state of the atmosphere-ocean decreased (cf.…”

Moderate levels of oxygenation during the late stage of Earth's Great Oxidation Event

“…Thick sulfate evaporite deposits, consistent with high seawater sulfate concentrations and developed in a supposedly marginalmarine basin during the LE, have been linked to the buildup of an oxidant reservoir equivalent to more than 20% of the modern atmosphere-ocean oxidizing capacity (Blättler et al, 2018). However, an open-marine setting for this succession in the Onega basin on the Karelia craton has been recently questioned on sedimentological and geochemical grounds (Alfimova et al, 2022), and an apparently large thickness of the sulfate evaporite deposit might reflect a drill core intersection through the central part of a salt diapir rather than true stratigraphic thickness (cf. Esipko et al, 2014).…”