Study On Sedimentary Characteristic And Erosion Resistance Of Sediment Bedfrom Feiyantan Coast At The Yellow River Delta

The Yellow River delta has become a typical zone for interactional studies between land and ocean, owing to its characteristics such as less runoff, more sediment transport, weak coastal hydrodynamic, frequent change of the ocean outfall channel, and transformation from fast coastal accretion before to obvious coastal erosion now, sensitive response to the environmental change of drainage area, etc.Feiyantan tidal flat is located in the coast of Diaokou River subdelta. Safety of the Feiyantan Oil-field behind the seawalls has been threatened seriously because of the violent coastal erosion since the ocean outfall channel of the Yellow River was changed to the Qingshuigou River in May, 1976.Core HF, about 30m depth, was obtained at intervals of 1m from the high tidal flat of Feiyantan at station 106 on the northern coast of the Yellow Rive Delta. After the samples were cut open, 183 ones were chosen for paticle size and magnetism analysis, 13 ones for basic engineering mechanics measure and 15 ones for erosion experiment in uniform flows. It aims to discuss the relationship between sedimentary characteristic of the sediment and the erosion resistance for samples taken at different depth, based on the fine resolution sedimentary sequence.The main conclusions are as follows:1. In core HF, the silt content is the highest, the clay content is the second and the the sand content is the lowest. Clayey silt, sandy silt, silt and silty sand are the main sediment types and different types of sediment distribute in different depth. The clay content and silt content all change stepwise against depth, whereas the sand content changes within a wide range at the top and deep layers, and within a narrow range at the middle layer. The change of granularity parameters also shows obvious regularity, which can be divided into eight layers. The main propeties of particle size frequency curves of typical samples are single kurtoses, minus skewness, longer thin trail and the mode values are between 3 Φ and 6 Φ.2. The lower (B₎)_cr ferrimagnetic minerals dominate the magnetic properties of most samples in core HF, but the contribution of anti-ferromagnetic minerals cannot be neglected in some samples. Pseudo-single domain (PSD) / multi-domain (MD) in size is the main component, but single domain (SD) / pseudo-single domain in size dominates the magnetic properties of the samples in the depth of 14.4-20.4m. Thermomagnetic curves of the typical samples reveal that magnetite series are the...