江苏岸外东沙沙脊群的沉积特征

江苏岸外辐射沙洲共由10多条形态完整的大型海底沙脊群构成,地形地貌复杂独特。东沙沙脊群是其中的第二大沙脊群,研究其沉积特征可以为揭示东沙乃至整个辐射沙洲海域的沉积环境提供依据。根据在江苏岸外东沙沙洲和条子泥沙洲(高泥和二分水)分别选取的8个和2个剖面的表层沉积物样粒度分析资料,分析其表层沉积物特征,结果表明:(1)东沙沙脊群的沉积物主要有砂、砂质粉砂和粉砂质砂三种类型;(2)搬运形式以跃移组分为主,悬移组分次之;(3)沉积物的平面分布特征主要表现为,东沙沙脊群的外缘沙洲和沙洲外缘沉积物较粗、越向沙洲中部沉积物越细;在东西方向上,西部细、东部粗;在南北方向上,具有对称分布、分级分布的特点;(4)东沙沙脊群沉积物的分布特征受风浪和潮流影响较大。

Sedimentary Characteristics of the Dongsha Sandbanks off Jiangsu Province

There are more than ten submerged sandbars on the radial tidal sands off Jiangsu Coast. The geomorphology is very complex and special. The Dongsha sandbank is the secondlargest of the radial tidal sandbanks. The studies on the sediment character can provide the evidence which will reveal the sediment environment of the Dongsha sandbank and the radial tidal sands. Eight and two profiles are chosen in the Dongsha sandbank and the Tiaozini sandbank. Along the profiles 43 samples are taken. Through computing the grain size parameters, many results are obtained. The sediment is sand, sand-silt and silt-sand and the most sediment moves by jumping and a little by suspending. The plane distribution is that the central section is fine and the outside is coarse, the west sediment is fine and the east sediment is coarse, the sediment from north to south is symmetrical and graded. The distribution is mainly influenced by waves and tidal flows.