In carbonate‐forming environments, authigenic minerals can cement surface sediments into centimeter‐sized intraclasts that are later reworked into “flat‐pebble” or “edgewise” conglomerates. Flat‐pebble conglomerates comprise only a small portion of facies in modern marine environments but are common in ancient strata, implying that seafloor cements were more widespread in the past. Flat‐pebble conglomerates nearly disappeared after the Ordovician radiation, yet it is unclear if this decline was due to changing seawater chemistry or if increased infaunalization and bioturbation simply worked to break down nascent clasts. We discovered a process analog that produces flat‐pebble conglomerates around the Great Salt Lake, Utah, USA, and studied these facies using field observations, wave models, satellite imagery, petrography, and microanalytic chemical data. Clasts were sourced from wave‐rippled grainstone that cemented in situ in offshore environments. Lake floor cements formed under aragonite saturation states that are lower than modern marine settings, suggesting that physical processes are at least as important as chemical ones. Results from our wave models showed that coarse sediments near the field site experience quiescent periods of up to 6 months between suspension events, allowing isopachous cements to form. Using a simple mathematical framework, we show that the main difference between Great Salt Lake and modern, low‐energy marine settings is that the latter has enough bioturbating organisms to break up clasts. Observations from Great Salt Lake demonstrate how geologic trends in flat‐pebble abundance could largely reflect changes in total infaunal biomass and ecology without requiring regional‐to‐global changes in seawater chemistry.

中文翻译：

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碳酸盐岩破胞体的物理控制：犹他州大盐湖的现代扁平卵石

在形成碳酸盐的环境中，自生矿物可以将表面沉积物固结成厘米大小的碎屑，然后将其重新加工成“扁平卵石”或“边缘”砾岩。卵石砾石在现代海洋环境中仅占一小部分，但在古代地层中很常见，这意味着过去海底水泥的分布更为广泛。卵石砾石在奥陶纪辐射后几乎消失了，但是目前尚不清楚这种下降是否是由于海水化学的变化所致，还是由于增加的粪便消毒和生物扰动只是为了破坏新生的碎屑。我们发现了一个过程类似物，该过程类似物在美国犹他州大盐湖周围产生卵石砾石，并使用现场观察，波浪模型，卫星图像，岩相学，和微量分析化学数据。碎屑来自波纹状的花岗石，这些花岗石在海上环境中就地固结。在文石饱和状态下形成的湖底水泥含量低于现代海洋环境，这表明物理过程至少与化学过程同样重要。我们的波浪模型的结果表明，在田间场地附近的粗沉积物在悬浮事件之间经历了长达6个月的静止期，从而形成了等渗胶结物。通过一个简单的数学框架，我们证明了大盐湖与现代低能耗海洋环境之间的主要区别在于，后者具有足够的生物扰动生物来分解碎屑。