黄河三角洲冰-泥(沙)互层及其产出的沉积构造

ICE-MUD (SAND) ALTERNATIONS AND THEIR SEDIMENTARY STRUCTURES IN THE YELLOW RIVER DELTA

冬季,黄河三角洲独特的水文条件和气候环境形成了大量冰 泥互层的特殊现象。按成因,黄河三角洲上冰 泥互层可分为沉积型和侵蚀充填型两种。冬末春初,当气温回升,冰层融化,在冰 泥互层区可以形成3种特殊的、未见报道的沉积构造:冰成泥沙笋、冰成豆粒和冰融水滴坑。这些沉积构造和冰 泥互层区遗迹是冰 泥互层现象重要的地质记录,可用以指导古代地层中类似现象的识别和正确解释。冰 泥互层多发育于冬季广泛出露的边滩、心滩和部分河道上,是暴露与准暴露沉积环境和低温(±0℃)气候条件下的产物。结合黄河三角洲和莱阳盆地莱阳组马耳山段地层研究认为,对冰 泥互层及其产出的沉积构造的研究对于沉积环境和气候条件恢复具有重要意义。

Many icemud (sand) alternations grow under the special hydrogeologic and climatic conditions in the Yellow River delta in winter. According to their origins, these icemud (sand) alternations in the Yellow River delta may be divided into two basic types, depositional one and erosional and filling one. In early spring and late winter, icemud (sand) alternations can produce four kinds of special sedimentary structures, that is, iceinduced mudsand stalagmite, iceinduced pisolite, and water drip pit due to ice melting, with temperature rising and ice melting. These special sedimentary structures and traces of icemud (sand) alternations are important geological records left behind by the icemud (sand) alternations, and they can be used to effectively recognize and correctly interpret the similar phenomena in the ancient strata. Icemud (sand) alternations, which usually grow in point bars, channel bars and sometimes in channels, are products from the exposure or paraexposure environment in a climate condition of about 0℃. Therefore, study on the icemud (sand) beds and their sedimentary structures is important and useful for climatologists and geologists to restore paleoclimate and paleogeography.