黄河三角洲上的冰成隆丘的研究

黄河三角洲上发育了大量的冰成构造,非常引人注目,冰成隆丘便是其中的一种。冰成隆丘外观上呈丘状,以圆丘状者多见,少数呈长丘状、不规则台状、塔柱状、土堆状及火山状;规模不等,小者高数厘米,大者数十厘米,最大长度可达 1m以上;表面平滑或具有裂缝或有火山口状坑穴,或有大量豆状瘤状或根状构造。有的内部具有穹隆状层理,有的具有复杂的变形层理。冰成隆丘一般产在边、心滩上或河床上,共成因有三种:一是冰融水滴积;二是冰融陷拱隆;三是冰洞滴积。黄河特殊的水文、水动力及气侯条件使得冰层中有时含有 (大量 )泥砂或冰层之上被泥砂覆盖,当这些冰层融化时,其中或其上的泥砂便会随冰融水一道滴向地表,在地表的相应部位形成冰成隆丘;当冰层中有孔洞时,且其上又沉积了一层泥砂,那么当冰层溶化后,在孔洞的部位便会因拱隆而开成隆丘;如果边、心滩上的侵蚀坑穴中的冰层中心或其它部位有融化形成的孔洞或裂缝,那么冰层之中或之上的泥砂便会随冰融水一道沿孔洞或裂缝滴落到坑穴中,形成冰洞漏积隆丘冰成隆丘是一种暴露和低温 (± 0℃ )条件下的产物。其成因与黄河复杂的冰-水-泥砂作用有关。

Study on the Ice-induced Heaving in Yellow River Delta

A lot of ice induced sedimentary structures are developed on Yellow River delta and one of them is rernarkedly ice induced heaving． Ice-induced heaving has a hill-like shape in appearance and circutar hill-like ones is often seen,and a few of them have long hill-like,irregular platform,tower-colurnn,earth pyramid and volcanic shapes with different sizes ranging from several centimeters(small ones)to a{ew decades of centimeters(1arge oes)and the largest is more than one meter in length,The surfaces of ice-induced heavings are smooth or have fission or pits like crater,and or have a lot of pea-like nodule or root-like structures．Some of ice-induced heavings have dome-like bedding within its interior,and some have complex deformation beading．Generally,ice-induced hearings develop in channel bar or point bar of course beds．Their genesis may be divisible into three types;the first is formed by dropping deposition of ice-melt water；the second is formed by vaulting resulting from the breakdown caused by ice melting；the third is formed by dropping deposition from a ice hole． The unusual hydrology,hydrodynamics and climate conditions in Yellow River make the ice beds containing(a great deal)mud-silt or the ice beds covered by mud-silt．As those ice beds melt,the mud-silt contained in the ice beds covering the ice beds will drop to the ground surface with ice melt water and form ice-induced heaving in the relevant position．If a hole develops in the ice bed and in the meantime,it is also covered by a layer of mudsilt,and when the ice bed melt,a heaving will be formed in the relevant position due to vaulting．If the ice bed formed in erosion pit in the point bar or channel bar has a hole or a crack,the mud-silt will drop into the pit with the ice melt water along the hole or crack to form a heaving． Ice-induced heavings are formed in an exposure and lower temperature(±0℃)conditions and their genesis is related to the complex interactions of ice and sand．