Intrastratal flow is a process that is still poorly understood, rarely described and difficult to interpret in ancient rocks. Sediments in the Cretaceous lacustrine Gyeokpori Formation of southwestern South Korea contain some chaotically deformed sandstone layers with deformed mudstone clasts that are ascribed to this process. The interpretation is based on the fact that these layers cannot be explained as a result of subaqueous debris flows or mass transport, whereas the sedimentary context, including the presence of other soft-sediment deformation structures, indicates that intrastratal flow must have been physically possible. The sedimentary setting was a lake in which mainly siliciclastic rocks were deposited, with some interbedded volcaniclastics. The nearby volcanic activity caused seismic shocks that affected the unstable lake margins resulting in the dominance of gravity-flow deposits, but also in a high sedimentation rate that facilitated soft-sediment deformation partly caused by intrastratal flow. This must have happened fairly frequently during a probably limited time-span, as several layers showing traces of intrastratal flow are present within a succession of only <1 m thick. The combined data on the geological setting and our findings regarding the origin of the various soft-sediment deformation structures may help to recognize the traces left by intrastratal flow elsewhere in the geological record.

中文翻译：

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白垩纪 Gyeokpori 组的内流（韩国西南）

层内流动是一个在古代岩石中仍然知之甚少、很少描述和难以解释的过程。韩国西南部白垩纪湖相 Gyeokpori 组的沉积物包含一些混乱变形的砂岩层，其中包含归因于这一过程的变形泥岩碎屑。解释是基于这样一个事实，即这些层不能被解释为水下泥石流或质量运输的结果，而沉积环境，包括其他软沉积变形结构的存在，表明层内流动在物理上是可能的。沉积环境是一个湖泊，主要沉积硅质碎屑岩，夹杂一些火山碎屑岩。附近的火山活动引起地震冲击，影响不稳定的湖缘，导致重力流沉积物占主导地位，但也导致高沉积速率，促进了部分由层内流动引起的软沉积物变形。这一定在可能有限的时间跨度内相当频繁地发生，因为在仅 <1 m 厚的连续序列中存在显示出层内流动痕迹的几层。地质背景的综合数据和我们关于各种软沉积变形结构起源的发现可能有助于识别地质记录中其他地方的层内流动留下的痕迹。这一定在可能有限的时间跨度内相当频繁地发生，因为在仅 < 1 m 厚的连续序列中存在显示层内流动痕迹的几个层。地质背景的综合数据和我们关于各种软沉积变形结构起源的发现可能有助于识别地质记录中其他地方的层内流动留下的痕迹。这一定在可能有限的时间跨度内相当频繁地发生，因为在仅 <1 m 厚的连续序列中存在显示出层内流动痕迹的几层。地质背景的综合数据和我们关于各种软沉积变形结构起源的发现可能有助于识别地质记录中其他地方的层内流动留下的痕迹。