Bed forms in submarine channels; comparison of ancient examples from Greece with studies of Recent turbidite systems
Bed forms in submarine channels; comparison of ancient examples from Greece with studies of Recent turbidite systems
复制标题
海底通道中的河床形态；
DOI：
10.1306/d4267d70-2b26-11d7-8648000102c1865d
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发表时间：
1994
影响因子：
2
通讯作者：
N. Kontopoulos
中科院分区：
文献类型：
--
作者：
D. Piper;N. Kontopoulos
摘要侧扫声纳观测表明，现代海洋浊流通道中存在砾石波、笛状冲刷和平行侵蚀沟。类似的特征在古代岩石中并不常见。研究了希腊西部两个新生代暴露良好的浊积岩河道充填剖面，以确定为什么这些特征在古代地质记录中难以识别，以及哪些沉积相与大型砾石床形式相关。古河道充填物中的砾石波形成于层顶级配不良的块状砾岩中。它们与高密度桑迪浊流组合的砂岩一起被发现。一系列几米大小的侵蚀冲刷，类似于现代的长笛状冲刷，已被绘制在一个古老的河道填充物的碎屑流沉积物表面上。在古代地质记录中很难识别大型砾石层，因为它们的规模和缺乏独特的特征来帮助横向对比露头中的小间隙。与现代沉积物和沉积物组合的类比表明，沉积发生在主要桑迪沉积中心的上坡河道中。与现代砾石层形式相关的侵蚀特征在古代记录中很难识别，因为页岩暴露不良。
ABSTRACT Side-scan sonar observations have shown the presence of gravel waves, flute-like scours, and parallel erosional furrows in modern marine turbidity-current channels. Similar features are not well known from ancient rocks. Two Cenozoic sections of well-exposed turbidite channel fill in western Greece have been studied to determine why such features are difficult to recognize in the ancient geological record and which sedimentary facies are associated with large gravel bed forms. Gravel waves in ancient channel fills form in massive conglomerates with poor grading at the top of beds. They are found with sandstones of the high-density sandy turbidity current association. Series of erosional scours a few meters in size, similar to modern flute-like scours, have been mapped on the surface o debris-flow deposits in one ancient channel fill. Large gravel bed forms are difficult to recognize in the ancient geological record because of their scale and lack of distinctive features to aid lateral correlation across minor gaps in outcrop. Analogy with modern deposits and the sediment association suggest that deposition takes place in channels upslope from major sandy depocenters. The erosional features associated with modern gravel bed forms are difficult to recognize in the ancient record because of poor exposure of shales.