厦门胡里山西侧海滩沉积物粒度特征分析

Analysis of grain size characteristics in beach sediment south Xiamen Island

研究区海滩沉积物的粒度分析结果显示，（1）该区海滩中潮位沿线一带浅表层物质主要由粗砂至细砾级的颗粒组成，平均粒径（矩法值）为－0．1。粒度组成上有2～3个次组分，各组分的众数位分别平均为－1．2、0．4和2．5。（2）概率值累积曲线的各段呈“陡－缓－陡”的排布模式，与Visher的海滩沉积物的典型模式不同。且各正态组分间的截点与频率分布曲线上低谷的位置并不—一对应，特别是在最粗与次粗组分之间。表明正态组分间有强烈的混掺。（3）上述特征都与本区的强水动力有着密切关系。而岸段各处平面位置的不同造成相应部位波浪作用效果的差异，使本区南北两段产生粒度特征的分异；海岸动力的季节性变化则在表层与次表层的差异中得到反映。（4）近岸的陆上侵蚀碎屑物质是考虑本区海滩物源时应注意的一个重要因素。

Grain size characteristics and their variations in the sediment of studied area have been analyzed after field sampling with accuracy positioning, grain size analysis data processing by a newly developed software, and comprehensive analysis using grain slze distribution curves ,probability cumu1ative curves and grain size parameters. The result shows that, (1 ) The upper layer of the sedIment in the studied area is composed of coarse grained materials,mainly coarse sand and fine gravel, with 1he mean dlameter of - 0, 11.There are two or three components in the frequency distributive curves,with the mode of - 1. 2, 0. 4, 2. 5 respectively. (2) The probability cumulative curve has three main parts wlth the slop of steep-gentle-steep order, which is completely different from Visher's model for the beach sediment. And, the truncation points do not correspond to the trough positions in the fre quency distributive curve,especlally those between the coarse and intermediate components, showing that there exlsts a strong mixing. (3) All the characters above are closely related to the strong local c0astal dynamics. The different dynamic conditions in the different part of the studied area results in the difference of grain size characteristics between south and north of the area. And the seasonal variation of the coastal dynamics has also been reflected in the difference of the grain size characters between the surface and sub-surface sediment samples. (4) The eroded clastic mater1a1 from the land drainage system to the beach is an important factor as the material supply of thls beach area.