南海某些表层沉积硅藻的分布及其古环境意义

DISTRIBUTIONS OF THE SURFACE SEDIMENT DIATOMS FROM THE SOUTH CHINA SEA AND THEIR PALAEOCEANOGRAPHIC SIGNIFICANCE

本文通过对南海表层沉积物样品的硅藻分析,试图揭示南海某些表层沉积硅藻的分布规律,以便为南海古海洋学研究提供科学依据。研究发现,Thalassionema nitzshioides 为南海地区表层沉积硅藻的优势种,且其百分含量无明显的区域差异,体现了南海与周围海洋水体交换相对较弱的特征。除此之外,南海表层沉积硅藻的分布主要受到海洋环流的影响,表现在黑潮暖流、印度洋暖水的入侵以及沿岸流对南海表层沉积硅藻分布的影响。其中,Nitzshia marina, Azpeitia neocrenulata, Azpeitia africana, Rhizosolenia bergonii 等暖水硅藻可作为黑潮暖流及印度洋暖水入侵南海强度的指标种。而Cyclotella stylorum, Cyclotella striata, Diploneis bombus, Traychneis as pera, Tabularia tabulata 等则可看作判断沿岸流对南海水体影响强度的标志种。

The purpose of this paper is to find the distribution patterns of some typical diatoms from the surface sediments in the South China Sea(SCS) and to discuss the relationship between the distributions of surface sedi-ment diatoms and the ocean environments, especially the current pattern of SCS. The result shows that the subtropical planktonic species Thalassionema nitzshioides dominates the surface sediment diatom assemblages throughout SCS with relatively small changes, which indicates that the water-mass exchanges among SCS, the Pacific and Indian oceans are relatively small. The warm water planktonic species Nitzshia marina, Azpeitia neocrenulata, Azpeitia afriacana and Rhizosolenia bergonii can be used as an indicator of the intrusion of Kuroshio Current and Indian ocean warm water in the paleoenvironment reconstruction. Whereas Cyclotella striata, Cyclotella stylorum, Diploneis bombus, Traychneis aspera and Tabularia tabulata can be used to identify the influence of the coastal currents in SCS.