南海东北部表层沉积中钙质超微化石的分布特征

Distribution of calcareous nannofossils in surface sediments of the northeastern South China Sea

对南海东北部188个表层沉积样品进行了钙质超微化石分析。结果表明,除2个样品外,其他样品均含有超微化石,但丰度相差悬殊,在（9~1 684）个/10视域范围内变化。钙质超微化石相对丰度在平面上的分布可划分为3个区。共鉴定出钙质超微化石17属27种,以Florishaera profunda,Gephyrocapsa oceanica,G.spp.（small）和Emiliania huxleyi为优势种。调查区钙质超微化石的分布受多种因素的综合影响。重点讨论了水深、陆源物质的输入、碳酸盐溶解作用等因素对超微化石丰度及优势种分布的影响。

This study analyzed calcareous nannofossils of the 188 surface sediment samples taken from the northeastern South China Sea. The results show that the relative abundance of these calcareous nannofossils is quite different. The highest abundance of nannofossils is 1684,but nannofossils are absent in two samples. The nannofossils assemblages are composed of 17 genera and 27 species,and Florishaera profunda,Gephyrocapsa oceanica,G. spp.（ small） and Emiliania. huxleyi are dominant species,which account for 90% of the assemblages. Nannofossils abundance is low in shelf,and is high in continental slope and deep-water basin. The factors controlling the distribution of nannofossils,including the water depth,dilution of terrigenous materials,deep sea carbonate dissolution and sea-water turbidity,are also discussed.