Isolated spherical carbonate concretions observed in marine sediments are fascinating natural objet trouve because of their rounded shapes and distinct sharp boundaries. They occur in varied matrices and often contain well preserved fossils. The formation process of such concretions has been explained by diffusion and rapid syn-depositional reactions with organic solutes and other pore water constituents. However, the rates, conditions and formation process of syngenetic spherical concretions are still not fully clear. Based on the examination of different kinds of spherical concretions from several locations in Japan, a diffusion based growth diagram was applied to define the generalized growth conditions of spherical concretions formed around decaying organic matter. All analytical data imply that the spherical concretions formed very rapidly, at least three to four orders of magnitude faster than previously estimated timescales. The values indicate that spherical concretions are preferentially grown within clay- to silt-grade marine sediments deposited in relatively deep (a few tens of metres) environments dominated by diffusive solute transport, very early in diagenesis.

中文翻译：

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早期成岩作用周围腐烂有机质周围球形碳酸盐胶结物形成的一般条件。

在海洋沉积物中观察到的孤立的球形碳酸盐岩凝结物由于其圆润的形状和明显的清晰边界而引人入胜。它们存在于不同的基质中，并且经常包含保存完好的化石。这种固结物的形成过程已经通过与有机溶质和其他孔隙水成分的扩散和快速的共沉积反应进行了解释。然而，同源球状结石的形成速率，条件和形成过程仍不完全清楚。基于对日本几个地区不同种类球形球状结石的研究，基于扩散的生长图被用来定义围绕腐烂有机物形成的球形球状结石的一般生长条件。所有分析数据都表明球形凝结物形成非常迅速，比以前估计的时间尺度至少快三到四个数量级。该值表明球形凝结物优先在成岩作用早期的较深（数十米）环境中沉积，该环境中的粘土至粉砂级海洋沉积物以弥散扩散的溶质运移为主。