Mid-latitudinal habitable environment for marine eukaryotes during the waning stage of the Marinoan snowball glaciation

作者：Huyue Song, Huyue Song, Zhihui An, Qin Ye, Eva E. Stüeken, Jun Hu, Jun Hu, Thomas J. Algeo, Li Tian, Daoliang Chu, Haijun Song, Jinnan Tong, Shuhai Xiao, Jinnan Tong · 发表于：Nature Communications · 年份：2023 · DOI：10.1038/s41467-023-37172-x · 被引用次数：42 · 研究领域：Paleontology and Stratigraphy of Fossils、Geology and Paleoclimatology Research、Marine Biology and Ecology Research

During the Marinoan Ice Age (ca. 654-635 Ma), one of the 'Snowball Earth' events in the Cryogenian Period, continental icesheets reached the tropical oceans. Oceanic refugia must have existed for aerobic marine eukaryotes to survive this event, as evidenced by benthic phototrophic macroalgae of the Songluo Biota preserved in black shales interbedded with glacial diamictites of the late Cryogenian Nantuo Formation in South China. However, the environmental conditions that allowed these organisms to thrive are poorly known. Here, we report carbon-nitrogen-iron geochemical data from the fossiliferous black shales and adjacent diamictites of the Nantuo Formation. Iron-speciation data document dysoxic-anoxic conditions in bottom waters, whereas nitrogen isotopes record aerobic nitrogen cycling perhaps in surface waters. These findings indicate that habitable open-ocean conditions were more extensive than previously thought, extending into mid-latitude coastal oceans and providing refugia for eukaryotic organisms during the waning stage of the Marinoan Ice Age.