Fig. 4: Cartoon showing the evolution of the oceanic P cycle during the Cryogenian and Ediacaran.
From: A phosphate-rich marine reservoir in the redox stratified Ediacaran ocean
a During global glaciations of the Cryogenian Period, the ocean was redox stratified and widespread IF deposition occurred. Intense subglacial weathering led to enhanced P/Fe ratios relative to earlier IFs3. b During the Ediacaran period, the ocean was also redox stratified. However, the enhanced generation of dissolved sulfide, including the development of water column euxinia in some mid-depth oceanic settings, promoted recycling of phosphate back to the water column. High dissolved Fe2+ concentrations in some areas caused local deposition of IFs, which record the high water column phosphate concentrations (via elevated P/Fe ratios).
