Song Yafang, Bowyer Fred T, Mills Benjamin J W, Merdith Andrew S, Wignall Paul B, Peakall Jeff, Zhang Shuichang, Wang Xiaomei, Wang Huajian, Canfield Donald E, Shields Graham A, Poulton Simon W
School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UK.
School of GeoSciences, University of Edinburgh, James Hutton Road, Edinburgh, EH9 3FE, UK.
Nat Commun. 2023 Oct 20;14(1):6640. doi: 10.1038/s41467-023-41901-7.
Controls on Mesoproterozoic ocean redox heterogeneity, and links to nutrient cycling and oxygenation feedbacks, remain poorly resolved. Here, we report ocean redox and phosphorus cycling across two high-resolution sections from the ~1.4 Ga Xiamaling Formation, North China Craton. In the lower section, fluctuations in trade wind intensity regulated the spatial extent of a ferruginous oxygen minimum zone, promoting phosphorus drawdown and persistent oligotrophic conditions. In the upper section, high but variable continental chemical weathering rates led to periodic fluctuations between highly and weakly euxinic conditions, promoting phosphorus recycling and persistent eutrophication. Biogeochemical modeling demonstrates how changes in geographical location relative to global atmospheric circulation cells could have driven these temporal changes in regional ocean biogeochemistry. Our approach suggests that much of the ocean redox heterogeneity apparent in the Mesoproterozoic record can be explained by climate forcing at individual locations, rather than specific events or step-changes in global oceanic redox conditions.
中元古代海洋氧化还原异质性的控制因素以及与营养物质循环和氧合反馈的联系，仍然没有得到很好的解决。在这里，我们报告了华北克拉通约14亿年前下马岭组两个高分辨率剖面的海洋氧化还原和磷循环情况。在下部剖面中，信风强度的波动调节了一个铁质氧含量最低区域的空间范围，促进了磷的消耗和持续的贫营养条件。在上部剖面中，高但变化的大陆化学风化速率导致了高硫化还原条件和弱硫化还原条件之间的周期性波动，促进了磷的循环和持续的富营养化。生物地球化学模型表明，相对于全球大气环流单元的地理位置变化可能如何驱动了区域海洋生物地球化学的这些时间变化。我们的方法表明，中元古代记录中明显的许多海洋氧化还原异质性可以用个别地点的气候强迫来解释，而不是全球海洋氧化还原条件的特定事件或阶跃变化。
