现代黄河三角洲的结构、发育过程和形成模式

FRAMEWORK, DEVELOPING PROCESSES AND SEDIMENTARY MODEL OF THE MODERN HUANGHE RIVER DELTA

对现代黄河三角洲典型河道——钓口流路的不同钻孔剖面分析,阐明现代黄河三角洲单个流路所形成的三角洲叶片体的沉积物与沉积相的空间分布特征.结合单流路河道的小循环演化规律,划分现代黄河三角洲的发育过程为四个阶段,提出了三角洲的河口坝沉积相间分布的横向沉积序列、主河道型与出汊河道型两个不同的纵向沉积序列及河口坝型与口坝侧湾型两个不同的垂向沉积序列.在此基础上,提出了现代黄河三角洲的形成模式.

The modern Huanghe River Delta is a special type of delta. It is charac-terized by high sediment content, high sediment discharge, high constructing rate, fine-grain sediment dominant of silt and clay, aboveground channel, frequent forking of tail-channel, weak ocean hydrodynamic condition (wave and tide etc.), and shallow receiving basin. Based on the study of three cross and one Ipngitudinal sections from different units of the abandoned Diaokou Chan-nel, three dimensional distribution of sediment and sedimentary subfacies of the lobe formed by the single channel of the modern Huanghe River Delta is clarified; together with the evolionary rule of minor cycle of tail-channel migrating, developing processes of the modern Huanghe River Delta can be di-vided into foui stages:(1) Inundating-filling-bay-accumulating stage;(2) Channe-lizing-converging-extending-seaward-eroding stage; (3) Forking-filling-deposi-ting stage; (4) Eroding-landward-forking of shelly beach (or shelly beach rid-ge)-equilibrium stage, and sedimentary sequences of the modern Huanghe River Delta can be suggested as: one lateral sequence of the interval distribution of mouth bar subfacies, two different longitude sequences of main-channel-type and forking-channel-type, and two different vertical sequences of mouth-bar type and side-bay-of-mouth-bar type. Finally, the model of the modern Huanghe River Delta is proposed.