Dynamic Nutrient Cycling Regulation of Organic Carbon Burial in the Mid-Proterozoic Ocean

The significance of nutrient availability in regulating the evolution of carbon cycles within Earth’s surface environment is indisputable. The mid-Proterozoic (1800 to 800 Ma) is commonly viewed as a period characterized by long-term oligotrophic ocean, resulting from prolonged climatic, atmospheric and tectonic stability, which may have further suppressed the efficiency of biogeochemical cycling of carbon. In contrast, our geochemical analyses of bio-essential trace elements (Zn) within mid-Proterozoic successions reveal a pattern of dynamic nutrient cycling, uncovering how changes in availability (and scarcity) of these critical nutrients in ocean influenced the evolution of carbon cycle throughout the mid-Proterozoic. We further review several mid-Proterozoic volcanic events, including global large igneous province (LIP) and regional subaerial volcanism, to elucidate the pattern of volcanically modulating nutrient cycles at that time. We propose that nutrient cycling in the mid-Proterozoic ocean was not monotonic, but rather had a more complex feedback among climate, oceanic temperature, and organic carbon burial than previously thought.