Heterogeneous redox evolution of the Meso-Neoproterozoic ocean: Insights from eastern China

Redox-sensitive element (RSE) compositions in marine sedimentary archives have been important in improving our understanding of redox history, especially in the Meso-Neoproterozoic ocean, where early biological innovations took place before the Cambrian Explosion. However, despite increasing availability of RSE data that represent this long time interval, temporal comparisons are difficult, and thus provide poor constraints on the dramatic changes in atmosphere-ocean chemical settings. Here we analyzed carbonate rocks and black shales from the North China and Yangtze platforms (eastern China) for trace elements and isotopic compositions (δ13C, δ34S and 87Sr/86Sr). These data were combined with previously published RSE data to allow establishment of successive elemental chemostratigraphies from sequences of both black shale and carbonate RSE archives, thus yielding direct insights into the role of marine RSE cycling. Generally low Th/RSE ratios in relatively pure carbonate rocks (Al