Open-Coast Tidal Flats
Open-Coast Tidal Flats
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DOI：
10.1007/978-94-007-0123-6_9
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发表时间：
2012
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影响因子：
--
通讯作者：
Daidu Fan
中科院分区：
文献类型：
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作者：
Daidu Fan
最近的研究进展强调了开阔海岸潮坪沉积体系在现代和古代海岸环境中的重要性。该系统是独特的，在其波浪和潮汐为主的物理环境，特别是从潮汐为主的禁止潮滩和波浪为主的shorefaces不同。不同时间尺度上波浪和潮汐的相互作用不仅产生侵蚀和沉积方面的周期性形态变化，而且还产生由风暴生成的砂为主层（SDLs）和风暴后泥为主层（MDLs）组成的韵律性沉积单元。开阔海岸潮滩的古代沉积物可以通过风暴产生的结构的丰富性和潮汐通道沉积物的稀缺性与阻挡潮滩的相区别，以及通过由组合流或波浪和潮汐的相互作用产生的结构的丰富性与（潮汐）滨面的相区别。泥质和桑迪开敞潮滩的差异也很显著。泥质开阔海岸潮滩倾向于沿着大型河流三角洲和邻近的贝壳堤平原发育，具有总体上的加积凸起剖面，具有清晰的分带性，并产生加积向上变细的潮间带序列。桑迪开敞海岸潮滩常见于小河流的开口河口和邻近的滨海平原，通常发育侵蚀上凹的剖面，通常在高潮附近存在具有粗粒沉积物的内部冲沙坝，并产生向上粗化的退积序列。桑迪开敞海岸潮滩的垂直演替一般比淤泥质开敞海岸潮滩包含更多的风暴床。值得注意的是，有一些加积的桑迪开放海岸潮滩，位于上述两个设置之间。因此，提出了一个新的频谱的海岸形态动力学设置的变化，从潮汐为主的阻挡潮滩，波浪影响和潮汐为主的泥质开放海岸潮滩，波浪和潮汐为主的增生桑迪开放海岸潮滩，波浪为主的侵蚀桑迪开放海岸潮滩，以波浪为主的潮汐岸线。
Recent research advances highlight the importance of open-coast tidal-flat depositional system in both modern and ancient coastal environments. The system is unique in its wave- and tide-dominated physical setting, notably distinct from the tide-dominated barred tidal flats and the wave-dominated shorefaces. Interactions of waves and tides over different time scales produce not only cyclic morphologic variations in terms of erosion and deposition, but also rhythmic depositional units consisting of storm-generated sand-dominated layers (SDLs) and post-storm mud-dominated layers (MDLs). Ancient deposits of the open-coast tidal flats can be distinguished by abundance of storm-generated structures and scarcity of tidal-channel deposits from those of barred tidal flats, and by abundance of the structures created by combined flows or the interactions of waves and tides from those of (tidal) shorefaces. Difference is also remarkable between muddy and sandy open-coast tidal flats. Muddy open-coast tidal flats tend to develop along mega-river deltas and the adjacent chenier plains, have a general accretional convex-up profile with clear zonation, and produce aggradational fining-upward intertidal successions. Sandy open-coast tidal flats are common in the open-mouth estuaries of small rivers and the adjacent strand plains, usually develop an erosional concave-up profile with common presence of inner swash bars having the coarsest sediment near the high water, and produce coarsening-upward retrogradational successions. The vertical successions of sandy open-coast tidal flats generally contain more storm-generated beds volumetrically than those of muddy open-coast tidal flats. Notably, there are some accretional sandy open-coast tidal flats, lying in between the above two settings. A new spectrum of coastal morphodynamic settings is therefore proposed to change from the tide-dominated barred tidal flats, the wave-influenced and tide-dominated muddy open-coast tidal flats, the wave- and tide-dominated accretional sandy open-coast tidal flats, the wave-dominated erosional sandy open-coast tidal flats, to the wave-dominated tidal shorefaces.