长江口北槽沉积物的粒度特征和输运趋势探讨

Discussion on grain-size characteristics of seafloor sediment and transport pattern in the northern passage of the Yangtze River estuary

基于长江口北槽沉积物样品的粒度分析结果,使用粒径趋势分析法,研究了北槽底质沉积物的分布特征和输运趋势。结果表明:北槽表层沉积物总体较细,沉积物组分以砂质粉砂和粉砂为主。北槽底床沉积物的总体分选性较差,偏态系数则处于极正偏和近对称之间;峰度系数小于1.8,为低峰态,频率曲线比较平缓。北槽深槽表层沉积物为双向输运,在低能环境下向陆搬运,在高能环境下向海搬运;北槽南边坡与深槽类似,而北槽北边坡表现为向陆搬运。在北槽深槽和南、北边坡出现输运差异,与它们所处的环境密切相关。

Grain-size distribution and transport pattern of sealfoor sediment data col ected from the northern passage of the Yangtze River estuary were studied using the Gao-Col ins grain-size trend analysis method with grain-size data. The results showed that the sediments are general y ifne in the northern passage, where sandy silt and silt are dominant. The sediments showed overal poor sorting, and skew ness coefifcient of between partial pole and nearly symmetric;kurtosis coefifcient was smal with less than 1.8 and platy kurtosis. In the deep trough the sediments were transported in a two-way direction;they were transported to land in a low-energy environment and to the sea in a high-energy environment. The transportation of sediments in the southern slope was similar to that in the deep trough. In the northern slope, the sediments were transported to land. The difference in the direction of sediment transport is closely related to their environment.