摘要:
气胀构造(Air heave structure)是一种相对不多见的沉积构造,但在黄河现代三角洲上却非常发育.它们可以发育在多种微相中,甚至在水上平原的分流河道的河床上也可以广泛发育.由于它们别致的形貌、精巧的结构而非常引人注目.在某些河段气胀构造密集成片、蔚为大观.黄河三角洲分流河道上的气胀构造一般呈圆形穹隆状,少数呈面状;直径多在数十厘米至1～2 m,面状者长宽最大可达数十米;高数厘米到二、三十厘米.气胀构造可以分为气盖、气室和基底三个部分.气盖厚十余厘米到二十余厘米,气盖表面光滑或有拱裂缝、爆裂缝、同心圈环、侵蚀坑槽、波痕、喷气泥沙火山、滑皱鳞片(或滑褶环脊)、泄气孔(坑、缝)及流痕等伴生或次生构造.黄河三角洲分流河道上的气胀构造的成因非常复杂,与黄河断流形成的独特水文、水动力条件及由此形成的河床的特殊结构和黄河沉积物的细粒(粘土、细粉砂)特性有关.
Abstract:
The air heave structure is a sedimentary phenomenon that is seldom observed, however, it is so well developed in the modern Yellow River delta that we may even find it on the riverbeds of the plains higher than the level of the water surface as well as many other minor sedimentary facies.They are very attractive for their unique looks and their finished configurations;w hat's more, they can show up in a large scale and present us a splendid sight in some reaches of the river. Most of the air heave structures developed in the Yellow River often show us as a circular dome in the shape,the rest as a plate;the diameter of them vary from scores of centimeters to one or two meters;as to those of plateshaped, the diameter of them can amount to scores of meters in the length as well as the width, and from several centimeters to twenties or thirties centimeters in the height. As to the configuration of the air heave structure, it was made up of three parts:the cover, the room and the base.The depth of its cover is f rom >10 centimeters to >20 centimeters.Some of the covers are smooth and some are sprinkled with arch cracks, imploded cracks, concentric quoits, eroded pits and slots, ripple marks, whiffing mud-sand volcanoes, slip and crimple squamas, air-discharging holes(pits, slot)and other accompanying or secondary structures such as some rill marks, and so on. The genesis of the air heave structures developed in the Yellow River is rather complex.By study ing the cause, we must relate it w ith the unique hy drology and the hydromechanical conditions fo rmed by the cut-off of the Yellow River and the co rrespondingly typical st ructure of the riverbed and the g ranule(clay and f ine siltite)characteristics of the sediments in the Yellow River.
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