江苏圆陀角附近潮滩表层沉积物粒度特征及其记录的海岸环境变化

Grain Size Characteristics of Surface Sediments at the Yuantuojiao Point,Jiangsu Province and the Indication of Coastal Environmenal ChangeS

圆陀角位于长江北支岸线与江苏海岸线的交汇处,发育了典型的潮滩地貌,表层沉积物粒度变化记录了潮滩环境变化的信息。圆陀角附近潮滩yb2和yb3断面表层沉积物粒度分析结果表明,采样点附近潮滩表层沉积物以粉砂为主,体现了粉砂淤泥质潮滩的沉积特征。恒大围垦海堤附近yb3断面表层沉积物绝大部分为砂,其呈现的砂质海岸特征是人类围垦和海洋动力分异的结果,即粗颗粒物质能适应高能环境得以沉积。3个断面表层沉积物粒度参数计算结果揭示,圆陀角附近潮滩属于淤积环境,仅在局部存在侵蚀的现象。圆陀角附近潮滩不同沉积区表层沉积物颗粒由粗到细的顺序分别是:海堤前潮滩>粉砂淤泥质光滩>互花米草滩。

The Yuantuojiao Point is located at the intersecting point between the north branch of the Changjiang River and the Jiangsu coastal line.A typical silt-muddy tidal flat forms on the coast.Grain size of surface sediments on the tidal flact recorded the information of environmental changes in the northern Changjiang River delta.The grain size data along the yb2 and yb3sections showed that silt was the dominant sedimentary type on silt-muddy tidal flat at the Yuantuojiao Point.Sediments along the yb3 section close to the Hengda Embankment are mostly of the sand,indicating the influences by reclaiming activities and the enhancement of marine dynamics.Grain-size parameters of sediments along the yb1,yb2,and yb3 sections reveal that the tidal flats at the Yuantuojiao Point are mostly depositional but slight erosion occurred locally.The finest sediments are mainly distributed on the tidal flat of Spartina alternflora near the Yuantuojiao Point.