The Athel silicilyte is an enigmatic, hundreds of meters thick, finely laminated quartz deposit, in which silica precipitated in deep water (>~100–200 m) at the Ediacaran–Cambrian boundary in the South Oman Salt Basin. In contrast, Meso‐Neoproterozoic sinks for marine silica were dominantly restricted to peritidal settings. The silicilyte is known to contain sterane biomarkers for demosponges, which today are benthic, obligately aerobic organisms. However, the basin has previously been described as permanently sulfidic and time‐equivalent shallow‐water carbonate platform and evaporitic facies lack silica. The Athel silicilyte thus represents a unique and poorly understood depositional system with implications for late Ediacaran marine chemistry and paleoecology. To address these issues, we made petrographic observations, analyzed biomarkers in the solvent‐extractable bitumen, and measured whole‐rock iron speciation and oxygen and silicon isotopes. These data indicate that the silicilyte is a distinct rock type both in its sedimentology and geochemistry and in the original biology present as compared to other facies from the same time period in Oman. The depositional environment of the silicilyte, as compared to the bounding shales, appears to have been more reducing at depth in sediments and possibly bottom waters with a significantly different biological community contributing to the preserved biomarkers. We propose a conceptual model for this system in which deeper, nutrient‐rich waters mixed with surface seawater via episodic mixing, which stimulated primary production. The silica nucleated on this organic matter and then sank to the seafloor, forming the silicilyte in a sediment‐starved system. We propose that the silicilyte may represent a type of environment that existed elsewhere during the Neoproterozoic. These environments may have represented an important locus for silica removal from the oceans.

中文翻译：

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阿瑟苏丹国Athel硅质岩的古生态学和古海洋学。

Athel硅质溶蚀物是一种神秘的，厚达数百米的精细层压的石英矿床，其中二氧化硅沉淀在南阿曼盐盆地Ediacaran-Cambrian边界的深水（>〜100-200 m）中。相比之下，海洋二氧化硅的中新元古代水槽主要局限于围岩环境。已知该硅酸盐电解质含有用于脱脂的甾烷生物标志物，如今它们是底栖的专性需氧生物。但是，该盆地以前被描述为永久性的硫化物和等价的浅水碳酸盐岩台地，且蒸发相缺乏二氧化硅。因此，Athel硅质溶质代表了一个独特的，未被广泛了解的沉积系统，对后期的埃迪卡拉安海洋化学和古生态具有影响。为了解决这些问题，我们进行了岩石学观察，分析了溶剂萃取性沥青中的生物标记，并测量了全岩石铁形态以及氧和硅同位素。这些数据表明，与阿曼同一时期的其他相相比，硅质溶质在沉积学，地球化学和存在的原始生物学方面都是独特的岩石类型。与边界页岩相比，硅质沉积物的沉积环境似乎在沉积物和可能的底部水域的深度上更加减少了，而生物群落的显着不同导致了生物标志物的保存。我们为该系统提出了一个概念模型，在该模型中，营养丰富的深层水通过间歇性混合与地表海水混合，从而刺激了初级生产。二氧化硅在这种有机物上成核，然后沉入海底，在缺乏沉积物的系统中形成硅质溶质。我们建议硅质岩可能代表新元古代时期其他地方存在的一种环境。这些环境可能代表了从海洋中去除二氧化硅的重要场所。