Study of the Slump Structure on the Yellow River Delta During Its in Zero
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摘要: 黄河断流后三角洲 (水上平原 )上的滑塌构造非常发育,在分流河道中几乎随处可见,它们主要发育在边滩、心滩外缘、周缘或内部的水道中,还可以发育在河床上。滑塌作用形成了三种产物:滑塌壁或滑塌缝 滑塌体和滑塌碎块及滑塌变形基底。滑塌壁或滑塌缝按力学机制可能分为两种类型 一种是张性 另一种是剪性。滑塌壁或滑塌缝的规模不一,大者长度可超过十余米,甚至二十余米,小者长度只有 3～ 5cm 滑塌体规模差别也较大,大者高度可超过 1m,长度可达 3～ 4m 小者高度和长度仅数cm。通过观察发现,滑塌构造的产生与波浪的掏洗和流水冲蚀有关,与地震和斜坡滑动关系不大。黄河断流后在某些低洼河道积水成“湖”,“湖”水在风的作用下形成波浪。波浪不断拍击导致边滩、心滩产生滑塌,形成一系列相应的滑塌构造 再者,黄河断流后边滩、心滩广泛暴露,黄河三角洲地区降雨后使边滩、心滩和河床上汇集成径流,径流的冲蚀也可以形成一系列滑塌构造。有的滑塌构造被风成砂埋藏后很容易被何存下来,而充填滑塌缝之间的风成砂经成岩作用之后则有可能转变成砂岩岩墙。Abstract: On the delta during Yellow River in zero,there developed a great number of slump structures,which might be formed near the edge of point bar and channel bar or in the channel developed whithin the point bar or channel bar,as well as in the river course.Slump may result in three products:one is slump wall and/or slump crack;the second is slump body,and the third is slump deformation basement.The slump wall and/or slump crack could be divided into two types according to the dynamic mechanics：one is of extension and the other of shearing.They has different sizes:the largest has more than ten meters in length and the smaller is not beyond three to five centimeters in length.The slump body is also defferent in sizes,and the largest may have one meter high and two or three meters long.and the smaller is a few centimeters in height and length.The observation indicates that the slump has been caused by wave and/or runing water washing and not by earthquake and/or sliding on slope. Interrupting of the Yellow River flow results in forming small ‘lake'in some lower courses and the water in the ‘lake'is blown by wind to forming wave.The wave-washing causes the wall of point bar and channel bar collapse,forming a series of slump structures.Interrupting of the Yellow River flow,meanwhile,makes almost all the point bar and channel bar exposed wholly and the rainfall in Yellow River delta is concentrated to form small runoff in the bar surface,which scours walls of the bar,resulting in forming a series of slump structures.Some of slump structures are buried by wind-induced sand and easily preserved,and the wind-induced sand filling in the slump fissures will become sand walls by diagenesis.
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Key words:
- slump structure /
- delta /
- Yellow River
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