SIMULATION-MODEL OF ALLUVIAL STRATIGRAPHY
SIMULATION-MODEL OF ALLUVIAL STRATIGRAPHY
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DOI：
10.1111/j.1365-3091.1979.tb00935.x
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发表时间：
1979-01-01
期刊：
影响因子：
3.5
通讯作者：
LEEDER, MR
中科院分区：
文献类型：
--
作者：
BRIDGE, JS;LEEDER, MR
提出的定量模型模拟了一个单一的主要河流穿过的洪泛平原下的二维冲积沉积序列的发展。考虑了影响河道带砂和砾石体在漫滩细粒中分布的几种相互关联的效应。它们是（a）横向可变的加积，（B）细沉积物的压实，（c）河漫滩边缘的构造运动，和（d）河道撕脱。该模型的选定实验表明，河道带沉积物的相互连接性和面密度如何随着河漫滩宽度/河道带尺寸、平均撕脱期和河道带加积速率的增加而降低。基于连通性和河道存款密度的流型分离是困难的。构造运动不会对层序产生重大影响，除非保持倾斜的首选方向（半地堑）。然后，表现出退覆趋势的河道带沉积往往聚集在活跃洪泛区边缘附近，留下主要是细粒冲积层积聚在非活跃侧。个别河道带沉积物在加积过程中发生了变化，尽管这种增厚可能会受到自我调节的限制。由加积作用产生的“多层”特征可能很难与由撕脱成因的不同河道带沉积物叠加而产生的特征区分开来。
The quantitative model presented simulates the development of a two‐dimensional alluvial sedimentary succession beneath a floodplain traversed by a single major river. Several inter‐related effects which influence the distribution of channel‐belt sand and gravel bodies within overbank fines are accounted for. These are (a) laterally variable aggradation, (b) compaction of fine sediment, (c) tectonic movement at floodplain margins, and (d) channel avulsion. Selected experiments with the model show how the interconnectedness and areal density of channel‐belt deposits decrease with increasing floodplain width/channel‐belt size, mean avulsion period, and channel‐belt aggradation rate. Separation of stream patterns based on interconnectedness and channel deposit density is difficult. Tectonic movements do not have a significant influence upon the successions unless a preferred direction of tilting is maintained (half‐graben). Then channel‐belt deposits showing offlap tendencies tend to cluster adjacent to the active floodplain margin, leaving dominantly fine‐grained alluvium to accumulate on the inactive side. Individual channel‐belt deposits thicken during aggradation, although a self‐regulating limit to such thickening is likely to operate. ‘Multistorey’features resulting from aggradation may be difficult to tell apart from those arising through superposition of distinct channel‐belt deposits of avulsive origin.