Paired U and Mo isotope evidence for pervasive anoxia in the Cryogenian early interglacial ocean

The delayed diversification of early animals until the middle Ediacaran Period, despite their likely origin in the Cryogenian Period or earlier, has been attributed to low levels of dissolved O2 in global seawater. To provide more robust constraints on the extent of global-ocean oxygenation during the mid-Cryogenian Period, we analyzed paired U (δ238U) and Mo (δ98Mo) isotope compositions of organic-rich shale in the basal Datangpo Formation from...