Ediacaran Phosphorus Cycling as a Trigger of Ocean Oxygenation

Several pulses of ocean oxygenation events were recognized in the Ediacaran period. However, the intrinsic triggers behind them remain ambiguous. Here we investigate the phase partitioning of phosphorus in the Ediacaran Doushantuo Formation, South China, to elucidate the role of recycled phosphorus in driving ocean oxygenation. High ratios of organic carbon to organic phosphorus in all samples relative to the Redfield ratio generally imply preferential release of phosphorus during the remineralization of organic matter. Notably, ratios of organic carbon to reactive phosphorus exceed the Redfield ratio during purported oxygenation intervals, but fall mostly below or close to the Redfield ratio in the rest of the section. Quantitative calculations suggest that enhanced benthic and water-column recycling created a phosphorus influx into the ocean that was comparable to or outpaced that of weathering input. Our study provides empirical evidence for untangling the mechanisms of the Ediacaran oxygenation.