Improved understanding of mouth bar morphodynamics, and the resulting stratigraphic architectures, is important for predicting the loci of deposition of different sediment fractions, coastal geomorphic change and heterogeneity in mouth bar reservoirs. Facies and architectural analysis of exceptionally well‐exposed shallow water (ca 5 m depth) mouth bars and associated distributaries, from the Xert Formation (Lower Cretaceous), of the Maestrat Basin (east‐central Spain), reveal that they grew via a succession of repeated autogenic cycles. An initial mouth bar accretion element forms after avulsion of a distributary into shallow standing water. Turbulent expansion of the fluvial jet and high bed friction results in rapid flow deceleration, and deposition of sediment in an aggradational to expansional bar‐form. Vertical bar growth causes flattening and acceleration of the jet. The accelerated flow scours channels on the bar top, which focuses further expansion of the mouth bar at individual loci where the channels break through the front of the mouth bar. Here, new mouth bar accretion elements form, downlapping and onlapping against a readily recognizable surface of mouth bar reorganization. Vertical growth of the new mouth bar accretion elements causes flattening and re‐acceleration of the jet, leading to channelization, and initiation of the next generation of mouth bar accretion elements. Thus the mouth bar grows, until bed‐friction effects cause backwater deceleration and super‐elevation of flow in the feeding distributary. Within‐channel sedimentation, choking and upstream avulsion of the feeding channel, results in mouth bar abandonment. In this study, mouth bars are formed of at least two to three accretion elements, before abandonment happened. The results of this study contrast with the notion that mouth bars form by simple vertical aggradation and radial expansion. However the architecture and facies distributions of shallow water mouth bars are a predictable product of intrinsic processes that operate to deposit them.

中文翻译：

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浅水河口坝的构造和演化的地层实例

增强对口岸形态动力学的认识以及由此产生的地层结构，对于预测口岸储层中不同沉积物组分的沉积轨迹，沿海地貌变化和非均质性非常重要。相和非常好，露出浅浅的水的结构分析（CAMaestrat盆地（西班牙中东部）的Xert地层（下白垩统）的5毫米深的口状条和相关的分流特征表明，它们是通过一系列重复的自生循环而生长的。在分流器撕成浅死水后形成初始的口条形吸积元件。河流射流的湍流膨胀和高床层摩擦导致水流快速减速，并且沉积物以从聚合到膨胀的棒状形式沉积。垂直杆的增长会导致射流变平并加速射流。加速的流动冲刷了杆顶部的通道，这使口杆进一步扩展到各个位置，通道在通道的各个位置突破了口杆的前部。在这里，形成了新的口形条增加元素，在易于识别的口杆重组表面上重叠和重叠。新的排气杆吸积元件的垂直增长会导致射流变平和重新加速，从而导致通道化，并引发下一代排气杆吸积元件。因此，口栏会一直增长，直到摩擦作用导致回水减速和进料分流中的流量超高为止。通道内的沉淀，阻塞和进料通道的上游撕脱导致口杆被遗弃。在这项研究中，在遗弃发生之前，口形条至少由两到三个吸积元素形成。这项研究的结果与“竖条由简单的垂直凝结和径向扩张形成”这一概念形成对比。