摘要
在内陆架浅海的近岸海底,发育着一种潮流成因的线状沙体,称潮流脊。其延伸方向与潮流流向一致,呈平行排列或指状伸展,它们沟脊相间,形态奇特。潮流脊在世界上分布相当广泛,它对航运、捕捞、水下工程、军事设施以及地下水和油气田的开发利用都具有重要意义。然而长期以来,人们在进行浅海地质学的研究时,却明显地忽视了潮流的作用,所以潮流脊这种分布广泛,并具有特殊意义的浅海地貌形态尚未被人们认识和重视。对它的命名也含混不清,如所谓浅滩、沙洲、暗沙、水下沙坝、海底沙丘等等,常常是因人因地而异。
Tidal current ridges,widely distributed geomorphological phenomena over the continental shelf of the world,are studied.They are formed by tidal current and the trend of their sand bodies runs parallel to the direction of tidal current.There are two types of the plane shapes:the parallel and the fingered.Conditions of forming tidal current ridges are the velocities of tidal current ranging from 1 to 3.5 knots and the supply of abundant sediments.Tidal current ridges often develop in following morphological locations:the bays,estuaries,the mouths of channels,as well as the offshore area with strong tidal current.Tidal current ridges occur generally at a water depth of less than 35 metres.The sediments of tidal current ridges are mainly composed of sand.The grain size of the sediments is uniform and well sorted.The characteristics of grain size of the sand imply that their formation mechanism is similar to that of river sand,that is,both of them are the result of flow movements in a trough channel controlled by boundary.There is however difference between them that the river sand is formed by one-way flow movement while the tidal current sand by two-way movement.There are two saltation populations in the log-probability curves of tidal current sand,the sorting of first saltation population is better than the second one,and having positive skewness,which differs from beach sand.In the C-M grain size pattern tidal current sand is most found in graded suspension segment.The continental shelves of the Yeuao Sea,the East China Sea and the South China Sea have favourable conditions for developing tidal current ridges in massive scale and special shape,such as the tidal current ridges in the offshore of Jiangsu,the Gulf of Korea,the shoal of Liaodong,the east and west mouths of the channel of Qiongzhou,Jiaozhou Bay,the shoal of Taiwan,Lingtinyang,the north branch of Changjiang estuary.The studies of them are of vital significance in shipping,fishing,submarine engineering,military installations,oil and gas explorations,as well as in scientific research.
作者
刘振夏
夏东兴
Liu Zhenxia;Xia Dongxing(First Institute of Oceanography,National Bureau of Oceanography)
出处
《海洋与湖沼》
1983年第3期286-296,共11页
Oceanologia Et Limnologia Sinica
