Microbial fossils preserved by early diagenetic chert provide a window into the Proterozoic biosphere, but seawater chemistry, microbial processes, and the interactions between microbes and the environment that contributed to this preservation are not well constrained. Here, we use fossilization experiments to explore the processes that preserve marine cyanobacterial biofilms by the precipitation of amorphous silica in a seawater medium that is analogous to Proterozoic seawater. These experiments demonstrate that the exceptional silicification of benthic marine cyanobacteria analogous to the oldest diagnostic cyanobacterial fossils requires interactions among extracellular polymeric substances (EPS), photosynthetically induced pH changes, magnesium cations (Mg²⁺), and >70 ppm silica.

中文翻译：

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元古代潮滩蓝藻硅化的新模型

早期成岩燧石保存的微生物化石为了解元古代生物圈提供了一个窗口，但促成这种保存的海水化学、微生物过程以及微生物与环境之间的相互作用并没有受到很好的限制。在这里，我们使用化石实验来探索通过在类似于元古代海水的海水介质中沉淀无定形二氧化硅来保存海洋蓝藻生物膜的过程。这些实验表明，类似于最古老的诊断蓝藻化石的底栖海洋蓝藻的异常硅化需要胞外聚合物 (EPS)、光合诱导的 pH 变化、镁阳离子 (Mg ²⁺ ) 和 > 70 ppm 二氧化硅之间的相互作用。