南海北部外陆架表层沉积物粒度参数特征及物源分析

摘要

为研究南海北部外陆架沉积物来源及沉积特征, 对南海北部外陆架18 个站位进行了表层沉积物取样和分析, 通过对沉积物的分类和粒度参数的计算, 探讨了沉积物类型和粒度参数的分布特征及其指示意义。研究结果表明, 研究区表层沉积物类型包括砾、砂质砾、砾质砂、砾质泥质砂、含砾砂、含砾泥质砂和含砾泥7 种类型。沉积物输运方式在外陆架以推移输运为主, 靠近内陆架区域以跃移和悬移为主。从外陆架向内陆架方向, 平均粒径变小, 分选程度变差, 偏态更加正偏, 峰形由尖窄单峰态变为宽平双峰态。南海北部外陆架靠近陆坡区域沉积物主要来源于末次冰期残留沉积物, 在WNW-N方向潮流作用下, 大致沿SE-NW 方向由外陆架向内陆架输运, 随着向内陆架方向靠近, 愈靠近华南大陆, 珠江等水系输运而来在陆源碎屑沉积物组成中所占比例增大。%In order to discuss the provenance of surface sediment in the outer continental shelf of the northern South China Sea, 18 surface sediment samples in the continental shelf were sampled and tested. Through the computation of average grain size, sorting coefficient and other grain size parameters, distribution of grain size parameters of surface sediment was obtained and analyzed. All samples can be classified into seven types in terms of grain size, which were gravel, sandy gravel, gravelly muddy sand, sand containing gravel, muddy sand containing gravel and mud containing gravel. From outer continental shelf to inner continental shelf, the changing trends of different grain size parameters were conspicuous, average grain size became smaller, sorting coefficient became larger, skewness became more positive, and kurtosis became larger. At sampling position that was closer to the continent of South China, diversity of provenance of surface sediment was strengthened. Hydrodynamic condition transporting the sediment comes from the WNW-N direction current, driving the sediment from SE to NW to the inner continental shelf. To the inner continental shelf, which is closed to China mainland, ratio of sediment transported from South China by the Pearl River and the Han River became bigger in the composition of surface sediment.