ABSTRACT

To explore the shallow marine redox state from the Ediacaran to the Cambrian (ca. 635–488.3 Ma) Yangtze Platform in southern China, this study presents traditional rare-earth element (e.g., δCe, δEu, REE distribution pattern and Y/Ho), enrichment factor, and paleoenvironment proxy data from the Kaiyang shelf from Nantuo to Loushanguan Formations. Our data from a drill core from Kaiyang suggest the occurrence of a fluctuating redox state from the Ediacaran to the Cambrian ocean, in which the fluctuating redox state of shallow water coexisted with eustatic change. We observe an obvious oxygenation signal of seawater during Ediacaran-Cambrian transition and a distinctive redox state in Ediacaran and Cambrian shallow seawater. We posit that the large-scale oxygenation of the atmospheric-oceanic system may have played a critical role in the main phase of Cambrian Explosion, and a fluctuating redox state of shallow seawater existed at the Cambrian stage.