Work

Constraining the age of the Ediacaran manganese deposits in South China using high resolution carbon isotope records

Year: 2025

Type: article

Abstract: The Ediacaran Period (635–539 Ma) marked a critical interval in Earth’s history, characterized by rapid diversification of multicellular eukaryotes and the emergence of metazoans. This period also approximately coincides with the formation of large-scale sedimentary manganese (Mn) deposits in South China. However, the age of these Mn deposits remains poorly constrained, hindering evaluation of economic and environmental significance. Here, we present high-resolution δ 13 C carb and δ 13 C org records from the Doushantuo Formation in the ZK12-15 drill core, located in the Chengkou basin on the northern margin of the Yangtze Platform. This drill core contains organic-rich black shales and rhodochrosite deposits, referred to in this study as the Gaoyan Mn deposits. Our δ 13 C carb profile reveals a pronounced negative excursion (down to −10.21‰) in the upper Doushantuo Formation overlying the Mn deposits. This negative shift at Gaoyan can be confidently correlated with the globally recognized Shuram negative δ 13 C carb excursion. These data indicate that rhodochrosite deposition at Gaoyan occurred prior to the onset of the Shuram event, constrained at ∼574 Ma. Combined with field observations, our results suggest that the organic-rich, black shale-hosted rhodochrosite deposit was possibly deposited contemporaneously with the widespread shallow-water phosphorite deposits in South China that preserve early animal embryos.

Source: Ore Geology Reviews

DOI: 10.1016/j.oregeorev.2025.106981