南海南部表层沉积物粒度分布特征及其影响因素

对取自南海南部的153个表层沉积物样品,进行了粒度、粒度参数计算和Q型聚类分析,探讨了表层沉积物的粒度分布特征、沉积类型及影响因素。结果表明,研究区沉积物主要粒级组分为黏土和粉砂,底质类型主要为泥,还有粉砂质砂、砂质粉砂和粉砂,平行于等深线基本呈带状分布;结合Q型聚类分析结果,研究区沉积物可分为外陆架及陆架坡折区粗粒沉积物(砂和粉砂)和陆坡区细粒沉积物(泥)两类,500 m等深线是两类沉积物的分界线;对比粒度分析结果,判定两类沉积物属于不同成因类型,外陆架及陆架坡折区是现代沉积和残留沉积的混合沉积,陆坡区是现代沉积;影响南海南部表层沉积物粒度分布的主要因素是物源、水动力条件、水深与地形及洋流。

GRAIN SIZE DISTRIBUTION OF SURFACE SEDIMENTS IN THE SOUTHERN SOUTH CHINA SEA AND INFLUENCING FACTORS

For a total of 153 surface samples taken from the southern South China Sea, grain size analysis, grain size parameters calculation and Q-mode hierarchical cluster analysis have been carried out, and the grain size distribution pattern, sediment types and influencing factors discussed in this paper. Among the samples, silty sand, sandy silt, silt and mud dominate, and the distribution of sediments is approximately parallel to the isobath in a zonal pattern, with mud as a major. Supported by Q-mode hierarchical cluster analysis, the sediments of research area can be divided into two types, coarse sediments (sand and silt) on the outer continental shelf and shelf break, fine sediment (silt) on the continental slope. The boundary of the two occurs along the isobath of 500 meters. Together with the data of grain size, it is deduced that the two types of sediment are from different origin, one is related to the mixing of the modern sediment and the relict sediment on the outer continental shelf and continental shelf break region, the other is the modern sediment on the continental shelf alone. The grain size distribution of surface sediments in the southern South China Sea is mainly dependant on provenance, hydrodynamic condition, water depth, geomorphology and current system.