Key Laboratory of Orogenic Belts and Crustal Evolution, MOE, School of Earth and Space Science, Peking University, Beijing, China.
Department of Atmospheric and Oceanic Sciences, School of Physics, Peking University, Beijing, China.
Nat Commun. 2021 Feb 11;12(1):955. doi: 10.1038/s41467-021-21114-6.
Geological evidence indicates that the deglaciation of Marinoan snowball Earth ice age (~635 Myr ago) was associated with intense continental weathering, recovery of primary productivity, transient marine euxinia, and potentially extensive CH emission. It is proposed that the deglacial CH emissions may have provided positive feedbacks for ice melting and global warming. However, the origin of CH remains unclear. Here we report Ni isotopes (δNi) and Yttrium-rare earth element (YREE) compositions of syndepositional pyrites from the upper most Nantuo Formation (equivalent deposits of the Marinoan glaciation), South China. The Nantuo pyrite displays anti-correlations between Ni concentration and δNi, and between Ni concentration and Sm/Yb ratio, suggesting mixing between Ni in seawater and Ni from methanogens. Our study indicates active methanogenesis during the termination of Marinoan snowball Earth. This suggests that methanogenesis was fueled by methyl sulfides produced in sulfidic seawater during the deglacial recovery of marine primary productivity.
地质证据表明，马兰诺冰期（约 6.35 亿年前）的冰川消融与强烈的大陆风化、初级生产力的恢复、海洋短期缺氧事件以及可能广泛的 CH 排放有关。有人提出，冰川消融期的 CH 排放可能为冰融化和全球变暖提供了正反馈。然而，CH 的来源仍不清楚。本研究报告了中国南方新元古代南沱组（马兰诺冰期的等沉积层位）同生黄铁矿的镍同位素（δNi）和钇-稀土元素（YREE）组成。南沱组黄铁矿的镍浓度与 δNi 之间以及镍浓度与 Sm/Yb 比值之间呈反相关关系，表明海水中的镍与产甲烷菌中的镍混合。我们的研究表明，在马兰诺雪球地球的终结过程中存在活跃的产甲烷作用。这表明，在海洋初级生产力的冰川消融恢复期，产甲烷作用是由海水中的硫化物产生的甲基硫提供燃料的。
